A Phase 2/3, Three-Part, Open-Label, Dose-Escalation, Age De-escalation and Randomized, Observer-Blind, Placebo-Controlled Expansion Study to Evaluate the Safety, Tolerability, Reactogenicity, and Effectiveness of mRNA-1273 SARS-CoV-2 Vaccine in Healthy Children 6 Months to Less Than 12 Years of Age
Phase: PHASE2
Conditions: SARS-CoV-2
Sponsor: ModernaTX, Inc.

ModernaTX, Inc. 
mRNA-1273-P204 Protocol Amendment 9 
mRNA-1273 
Confidential 
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CLINICAL STUDY PROTOCOL 
Protocol Title: 
A Phase 2/3, Three-Part, Open-Label, Dose-Escalation, 
Age De-escalation and Randomized, Observer-Blind, 
Placebo-Controlled Expansion Study to Evaluate the 
Safety, Tolerability, Reactogenicity, and Effectiveness of 
mRNA-1273 SARS-CoV-2 Vaccine in Healthy Children 
6 Months to Less Than 12 Years of Age 
Protocol Number: 
mRNA-1273-P204 
Sponsor Name: 
ModernaTX, Inc.  
Legal Registered Address: 
200 Technology Square 
Cambridge, MA 02139 
Sponsor Contact and 
Medical Monitor: 
 
ModernaTX, Inc. 
200 Technology Square 
Cambridge, MA 02139 
Telephone: 
 
e-mail: 
Regulatory Agency 
Identifier Number: 
IND: 019745 
Amendment Number: 
9 
Date of Amendment 9 
04 Aug 2022 
Date of Amendment 8 
23 May 2022 
Date of Amendment 7: 
18 Feb 2022 
Date of Amendment 6: 
07 Jan 2022 
Date of Amendment 5: 
29 Sep 2021 
Date of Amendment 4: 
25 Aug 2021 
Date of Amendment 3: 
23 Jul 2021 
Date of Amendment 2: 
17 Jun 2021 
Date of Amendment 1: 
30 Apr 2021 
NCT #: NCT04796896
PPD
PPD
PPD

ModernaTX, Inc. 
mRNA-1273-P204 Protocol Amendment 9 
mRNA-1273 
Confidential 
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Date of Original Protocol: 
24 Feb 2021 
 
CONFIDENTIAL 
All financial and nonfinancial support for this study will be provided by ModernaTX, Inc. 
The concepts and information contained in this document or generated during the study are 
considered proprietary and may not be disclosed in whole or in part without the expressed 
written consent of ModernaTX, Inc. The study will be conducted according to the 
International Council for Harmonisation (ICH) of Technical Requirements for Registration 
of Pharmaceuticals for Human Use, E6(R2) Good Clinical Practice (GCP) Guidance. 
 
 

ModernaTX, Inc. 
mRNA-1273-P204 Protocol Amendment 9 
mRNA-1273 
Confidential 
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PROTOCOL APPROVAL – SPONSOR SIGNATORY 
Study Title: 
A Phase 2/3, Three-Part, Open-Label, Dose-Escalation, Age 
De-escalation and Randomized, Observer-Blind, Placebo-Controlled 
Expansion Study to Evaluate the Safety, Tolerability, Reactogenicity, 
and Effectiveness of mRNA-1273 SARS-CoV-2 Vaccine in Healthy 
Children 6 Months to Less Than 12 Years of Age 
Protocol Number: 
mRNA-1273-P204 
Amendment Number: 
9 
Date of Amendment: 
04 Aug 2022 
 
Protocol accepted and approved by: 
 
 
See eSignature and date signed on 
the last page of document. 
 
 
ModernaTX, Inc. 
200 Technology Square 
Cambridge, MA 02139 
Telephone: 
 
 
Date 
 
 
 
 
PPD
PPD

ModernaTX, Inc. 
mRNA-1273-P204 Protocol Amendment 9 
mRNA-1273 
Confidential 
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DECLARATION OF INVESTIGATOR 
I have read and understood all sections of the protocol titled “A Phase 2/3, Three-Part, Open-Label, 
Dose-Escalation, Age De-escalation and Randomized, Observer-Blind, Placebo-Controlled 
Expansion Study to Evaluate the Safety, Tolerability, Reactogenicity, and Effectiveness of 
mRNA-1273 SARS-CoV-2 Vaccine in Healthy Children 6 Months to Less Than 12 Years of Age,” 
dated 04 Aug 2022, and the most recent version of the Investigator’s Brochure. 
I agree to supervise all aspects of the protocol and to conduct the clinical investigation in accordance 
with the current protocol, the International Council for Harmonisation (ICH) of Technical 
Requirements for Registration of Pharmaceuticals for Human Use, E6(R2) Good Clinical Practice 
(GCP) Guidance, and all applicable government regulations. I will not make changes to the protocol 
before consulting with ModernaTX, Inc. or implement protocol changes without institutional review 
board (IRB) approval except to eliminate an immediate risk to participants. 
I agree to administer study treatment only to participants under my personal supervision or the 
supervision of a subinvestigator. I will not supply study treatment to any person not authorized to 
receive it. I also agree that persons debarred from conducting or working on clinical studies by any 
court or regulatory agency will not be allowed to conduct or work on studies for the Sponsor or a 
partnership in which the Sponsor is involved. I will immediately disclose it in writing to the Sponsor 
if any person who is involved in the study is debarred, or if any proceeding for debarment is pending, 
or, to the best of my knowledge, threatened. 
I will not disclose confidential information contained in this document, including participant 
information, to anyone other than the recipient study staffs and members of the IRB. I agree to ensure 
that this information will not be used for any purpose other than the evaluation or conduct of the 
clinical investigation without prior written consent from ModernaTX, Inc. I will not disclose 
information regarding this clinical investigation or publish results of the investigation without 
authorization from ModernaTX, Inc. 
The signature below provides the necessary assurance that this study will be conducted according to 
all stipulations of the protocol, including statements regarding confidentiality, and according to local 
legal and regulatory requirements, US federal regulations, and ICH E6(R2) GCP guidelines. 
 
 
Signature of principal investigator 
 
 
Date 
 
 
 
 
Printed name of principal investigator 
 
 
 
 
 

ModernaTX, Inc. 
mRNA-1273-P204 Protocol Amendment 9 
mRNA-1273 
Confidential 
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PROTOCOL AMENDMENT SUMMARY OF CHANGES 
DOCUMENT HISTORY 
Document 
Date 
Amendment 9 
04 Aug 2022 
Amendment 8 
23 May 2022 
Amendment 7 
18 Feb 2022 
Amendment 6 
07 Jan 2022 
Amendment 5 
29 Sep 2021 
Amendment 4 
25 Aug 2021 
Amendment 3 
23 Jul 2021 
Amendment 2 
17 Jun 2021 
Amendment 1 
30 Apr 2021 
Original Protocol 
24 Feb 2021 
Amendment 9, (04 Aug 2022): Current Amendment 
Main Rationale for the Amendment 
The main rationale for this amendment is to provide an optional booster dose with 
mRNA-1273.214, a bivalent (Omicron-containing) adaptation of the original COVID-19 vaccine 
(mRNA-1273) used in this study, at least 3 months after Dose 2 to all participants who have not 
received a booster dose yet after their primary series with mRNA-1273. 
The summary of changes table provided below describes the major changes made to 
Amendment 9 relative to Amendment 8, including the sections modified and the corresponding 
rationales. The synopsis of the protocol has been modified to correspond to changes in the body 
of the protocol. Minor copy edits and administrative updates were made throughout the protocol 
to align with new content as well as for clarity, readability and/or accuracy. 
Summary of Major Changes in Protocol Amendment 9: 
Section # and Name 
Description of Change 
Brief Rationale 
2 (Objectives and Endpoints) 
Added primary objective to 
evaluate the safety of optional 
booster dose mRNA-1273.214 
by evaluating the primary 
endpoints of: 
• 
MAAEs through the entire 
study period. 
Added to evaluate the safety of 
mRNA-1273.214. 

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Section # and Name 
Description of Change 
Brief Rationale 
• 
SAEs through the entire 
study period. 
• 
AESIs through the entire 
study period. 
• 
AEs leading to 
discontinuation from study 
participation post-booster 
dose or post-third dose 
through the last day of 
study participation. 
3.1 (General Design) 
Specified all participants who 
have not yet received a booster 
dose will be offered a booster 
dose with mRNA-1273.214 
(instead of mRNA-1273). 
To provide an optional booster 
dose, mRNA-1273.214, a 
bivalent (Omicron-containing) 
adaptation of the original 
COVID-19 vaccine 
(mRNA-1273) used in this 
study. 
Updated Table 4 to include 
mRNA-1273.214 in the column 
titled booster dose. 
To state the doses for the 
mRNA-1273.214 optional 
booster. 
Added the text in the Study 
Progression section: 
Part 1 and Part 2 participants 
who have not yet received a 
booster dose with mRNA-1273, 
nor a non-study vaccine booster 
dose  will be offered an optional 
booster dose lower than the 
chosen primary series for each 
age group (Table 4), at least 
3 months after Dose 2 of 
mRNA-1273. 
To provide explanation that the 
optional booster dose, 
mRNA-1273.214, will be at 
lower doses than the primary 
series. 
3.3 (Justification for Dose, 
Control Product, and Choice of 
Study Population) 
Text added stating in case of 
EUA being granted for 
mRNA-1273, the participants 
will have 4 months from date of 
EUA to elect to cross-over to 
mRNA-1273 within the study. 
To specify time period 
participants will have from date 
of EUA to elect to cross-over to 
mRNA-1273 within the study. 
5.1 (Investigational Product 
Administered) 
Included mRNA-1273.214 
vaccine (at doses of 10 and 
25 µg) for the description of the 
term IP, added the composition 
of the mRNA-1273.214 vaccine, 
To provide a description of the 
composition of the 
mRNA-1273.214 optional 
booster. 

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Section # and Name 
Description of Change 
Brief Rationale 
and described the chemical 
make-up and visual appearance 
of the mRNA-1273.214 
injection. 
5.3.1 (Preparation of Study 
Vaccine for Injection) 
Added a 10-µg dose of 
mRNA-1273.214 and a 25-µg 
dose of mRNA-1273.214 
optional booster. 
To update with mRNA-1273.214 
optional booster doses to 
describe preparation of all study 
vaccines for injection. 
5.3.2 (Administration of Study 
Vaccine), 3.3 (Justification for 
Dose, Control Product, and 
Choice of Study Population) 
Clarified which participants will 
be offered the optional booster 
dose, mRNA-1273.214 , and/or 
time of availability. 
To align with Section 3.1 
(General Design). 
7.1.1 (Use of Electronic Diaries) 
Deleted “For participants who 
receive booster doses, eDiary 
will also be used starting at 
BD-Day 43 through BD-Day 
155.” 
To align with the SoA. 
7.4.3 (Solicited Adverse 
Reactions) 
Added text to indicate that no 
eDiaries will be used after 
booster doses with 
mRNA-1273.214. 
Throughout body of document 
Stated that Covid-19 surveillance 
(illness visits and convalescent 
visits) would only be performed 
while there is still a blinded Part 
2 for any age group, after 
unblinding of trial, this would be 
discontinued. 
Trial is officially unblinded for 
all age groups and there is no 
longer a comparator group 
available for meaningful 
assessment of incidence rates as 
they relate to VE. 

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Section # and Name 
Description of Change 
Brief Rationale 
10.1 (APPENDIX 1: Schedule 
of Assessments) 
Updated to describe changes 
made to SoA tables 
for participants who received an 
optional booster dose (for Parts 1 
and 2) with mRNA-1273 under 
Protocol Amendment 7 and for 
participants who choose to 
receive a booster dose with 
mRNA-1273.214 under Protocol 
Amendment 9. 
To provide text description of 
changes and additions made to 
SoA for the addition of optional 
booster dose with 
mRNA-1273.214. 
Surveillance removed from all 
SoA tables.  
Trial is officially unblinded for 
all age groups and there is no 
longer a comparator group 
available for meaningful 
assessment of incidence rates as 
they relate to VE. 
Updated title of Table 15. 
To clarify that for participants 
who received a booster dose with 
mRNA-1273 under Protocol 
Amendment 7, Table 15 is the 
mRNA-1273 booster dose SoA. 
Updated title of Table 16. 
To clarify that Table 16 is the 
booster dose phlebotomy 
schedule for participants that 
chose to receive a booster dose 
under Protocol Amendment 7.  
Added Table 19. 
To provide a SoA for 
participants who choose to 
receive a booster dose with 
mRNA-1273.214 under Protocol 
Amendment 9. 
 
 

ModernaTX, Inc. 
mRNA-1273-P204 Protocol Amendment 9 
mRNA-1273 
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PROTOCOL SYNOPSIS 
Name of Sponsor/Company: ModernaTX, Inc. 
Name of Investigational Product: mRNA-1273 for injection  
Name of Active Ingredient: mRNA-1273 
Protocol Title: A Phase 2/3, Three-Part, Open-Label, Dose-Escalation, Age De-escalation and 
Randomized, Observer-Blind, Placebo-Controlled Expansion Study to Evaluate the Safety, 
Tolerability, Reactogenicity, and Effectiveness of mRNA-1273 SARS-CoV-2 Vaccine in 
Healthy Children 6 Months to Less Than 12 Years of Age 
Protocol Number: mRNA-1273-P204 
Study Period: Up to 24 months 
Phase of Development: Phase 2/3 
Estimated Date First Participant Enrolled: 15 Mar 2021 
Estimated Date Last Participant Completed: November 2023 
Total Number of Sites: Approximately 75 to 100 study sites in the United States and Canada 
Objectives and Endpoints 
Objectives 
Endpoints 
Primary Objectives 
Primary Endpoints 
• 
To evaluate the safety and 
reactogenicity of up to 3 dose levels 
(25, 50, and 100 µg) of mRNA-1273 
vaccine administered as 2 doses 
28 days apart in 3 age groups  
• 
Solicited local and systemic ARs through 
7 days after each injection 
• 
Unsolicited AEs through 28 days after each 
injection 
• 
MAAEs through the entire study period 
• 
SAEs through the entire study period 
• 
AESIs, including MIS-C and myocarditis 
and/or pericarditis, through the entire study 
period 
• 
To infer the efficacy of mRNA-1273 
(25, 50, and 100 µg, administered as 
2 doses 28 days apart) based on 
immunogenicity in 3 age groups 
• 
The proportion of participants with a serum 
antibody level at Day 57 ≥ antibody threshold 
of protection 

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• 
If an accepted serum antibody threshold 
of vaccine protection against COVID-19 
is available, this analysis will form the 
basis to infer efficacy 
• 
The GM value of serum antibody level and 
seroresponse rate (SRR) from Study P204 
vaccine recipients at Day 57 compared with 
those from young adult (18 to 25 years of age) 
vaccine recipients (Day 57) in the clinical 
endpoint efficacy trial (Study P301) 
• 
If a threshold is not available, efficacy 
will be inferred by establishing 
noninferiority for each age group (6 years 
to < 12 years, 2 years to < 6 years, and 
6 months to < 2 years in Study P204) 
compared with 18- to 25-year old 
participants (Study P301) by both GM 
value of serum antibody levels and SRR. 
• 
For Part 3, the GM value of serum 
antibody level and SRR from Study P 204 
vaccine recipients at Day 57 compared 
with those from adult (≥ 18 years of age) 
vaccine recipients (Day 57) in the clinical 
endpoint efficacy trial (Study P301) 
• 
Seroresponse is defined as a titer 
change from baseline (pre-Dose 1) 
below the LLOQ to ≥ 4 × LLOQ, or at 
least a 4-fold rise if baseline 
is ≥ LLOQ 
• 
To evaluate the safety of mRNA-1273 
booster dose or third dose 
• 
Solicited local and systemic ARs through 
7 days after booster dose or third dose 
• 
Unsolicited AEs through 28 days after booster 
dose or third dose injection 
• 
MAAEs through the entire study period 
• 
SAEs through the entire study period 
• 
AESIs through the entire study period 
• 
AEs leading to discontinuation from study 
participation post-booster dose or post-third 
dose through the last day of study 
participation 
• 
To evaluate safety of 
mRNA-1273.214 booster dose 
• 
MAAEs through the entire study period 
• 
SAEs through the entire study period 
• 
AESIs through the entire study period 

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• 
AEs leading to discontinuation from study 
participation post-booster dose or post-third 
dose through the last day of study participation 
• 
To infer effectiveness of the 
mRNA-1273 booster or third dose by 
establishing noninferiority of Ab 
response after the booster dose or 
third dose in children in Study P204 
compared with post-primary series in 
adult recipients of mRNA-1273 in the 
clinical endpoint efficacy trial 
(Study P301) 
• 
GM value of post-booster (post-third dose) Ab 
in Study P204 compared with post-primary 
series (post-Dose 2) in adults (18 to 25 years) 
in Study P301 
• 
Seroresponse rate of post-booster (post-third 
dose) from baseline (pre-Dose 1) compared 
with post-primary series (post-Dose 2) from 
baseline (pre-Dose 1) in the adults (18 to 
25 years) in Study P301, using 4-fold rise 
definition 
• 
Seroresponse is defined as a titer change 
from baseline (pre Dose 1) below the 
LLOQ to ≥ 4 × LLOQ, or at least a 4 fold 
rise if baseline is ≥ LLOQ 
• 
For Part 3, the GM value and SRR of post-third 
dose Ab in Study P204 compared with post-
primary series (post-Dose 2) from adults 
(≥18 years of age) in Study P301 
Secondary Objectives 
Secondary Endpoints 
• 
To evaluate the persistence of the 
immune response to mRNA-1273 
vaccine (25, 50, and 100 µg)  
• 
The GM values of SARS-CoV-2 
S protein-specific bAb on Day 1, Day 57 
(1 month after Dose 2), Day 209 (6 months 
after Dose 2), Day 394 (1 year after Dose 2), 
BD-Day 1 (at least 3 months or 6 months after 
Dose 2), BD-Day 29 (1 month after booster 
dose or third dose), BD-Day 181 (6 months 
after booster dose or third dose), and BD-Day 
366 (1 year after booster dose or third dose) 
• 
The GM values of SARS-CoV-2-specific nAb 
on Day 1, Day 57 (1 month after Dose 2), 
Day 209 (6 months after Dose 2), Day 394 
(1 year after Dose 2), BD-Day 1 (at least 3 
months or 6 months after Dose 2), BD-Day 29 
(1 month after booster dose or third dose), 
BD-Day 181 (6 months after booster dose or 
third dose), and BD-Day 366 (1 year after 
booster dose or third dose) 
• 
To evaluate the incidence of 
SARS-CoV-2 infection after 
vaccination with mRNA-1273 or 
placebo 
• 
The incidence of SARS-CoV-2 infection 
including symptomatic and asymptomatic 
infection (by serology and/or RT-PCR) 
postbaseline 
• 
SARS-CoV-2 infection will be defined in 
participants with negative SARS-CoV-2 at 

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baseline: 
• 
bAb level against SARS-CoV-2 
nucleocapsid protein negative at Day 1, 
that becomes positive (as measured by 
Roche Elecsys) postbaseline, OR 
• 
Positive RT-PCR postbaseline 
• 
To evaluate the incidence of 
asymptomatic SARS-CoV-2 infection 
after vaccination with mRNA-1273 or 
placebo 
• 
The incidence of SARS-CoV-2 infection 
measured by RT-PCR and/or bAb-levels 
against SARS-CoV-2 nucleocapsid protein 
(by Roche Elecsys) postbaseline in 
participants with negative SARS-CoV-2 at 
baseline, in the absence of any COVID-19 
symptoms 
• 
To evaluate the incidence of COVID-
19 after vaccination with mRNA-1273 
or placebo. COVID-19 is defined as 
clinical symptoms consistent with 
COVID-19 AND positive RT-PCR for 
SARS-CoV-2 
• 
The incidence of the first occurrence of 
COVID-19 postbaseline, where COVID-19 is 
defined as symptomatic disease based on CDC 
case definition1  
Exploratory Objectives 
Exploratory Endpoints 
• 
To evaluate the genetic and/or 
phenotypic relationships of isolated 
SARS-CoV-2 strains to the vaccine 
sequence 
• 
Alignment of genetic sequence of viral 
isolates with that of the vaccine sequence 
• 
To describe the ratio or profile of 
specific S protein bAb relative to nAb 
in serum 
• 
Relative amounts or profiles of 
S protein-specific bAb and nAb titers in 
serum 
• 
To characterize the clinical profile and 
immune responses of participants with 
COVID-19 or with SARS-CoV-2 
infection  
• 
Description of clinical severity and immune 
responses of participants who are identified as 
infected by SARS-CoV-2 (COVID-19)  
• 
To assess, in a subset of participants, 
the SARS-CoV-2 S protein-specific T-
cell responses 
• 
Magnitude, phenotype, and percentage of 
cytokine-producing S protein-specific T cells, 
as measured by flow cytometry at different 
time points after vaccination relative to 
baseline 
• 
To explore asymptomatic 
SARS-CoV-2 infection after 
vaccination with mRNA-1273 or 
placebo in participants with serologic 
evidence of infection at baseline 
• 
GM and GMFR of bAb levels against 
SARS-CoV-2 nucleocapsid protein 
(quantitative IgG) 
• 
To evaluate immune response elicited 
by the primary series or booster dose 
or third dose of mRNA-1273 against 
• 
GM, SRR, and GMFR of Ab against 
variant(s) of concern or interest 

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Abbreviations: Ab = antibody; AE = adverse event; AESI = adverse event of special interest; AR = adverse 
reaction; bAb = binding antibody; BD = booster dose; CDC = Center for Disease Control; COVID-
19 = coronavirus disease 2019; GM = geometric mean; GMFR = geometric mean fold-rise; IgG = immunoglobin 
G; LLOQ = lower limit of quantification; MAAE = medically attended adverse event; MISC = multisystem 
inflammatory syndrome in children; mRNA = messenger RNA; nAb = neutralizing antibody; RT-PCR = reverse 
transcriptase polymerase chain reaction; S = spike; SAE = serious adverse event; SARS-CoV-2 = severe acute 
respiratory syndrome coronavirus 2; SRR = seroresponse rate. 
1 The case definition of COVID-19 includes at least one of the following systemic symptoms: fever (temperature 
> 38ºC/≥ 100.4ºF) or chills (of any duration, including ≤ 48 hours), cough (of any duration, including ≤ 48 
hours), shortness of breath or difficulty breathing (of any duration, including ≤ 48 hours), fatigue, headache, 
myalgia, nasal congestion or rhinorrhea, new loss of taste or smell, sore throat, abdominal pain, diarrhea, 
nausea or vomiting, poor appetite or poor feeding, AND a positive test for SARS-CoV-2 by RT-PCR. 
variant(s) of interest 
Overall Study Design 
This is a Phase 2/3, three-part, open-label, dose-escalation, age de-escalation and randomized, 
observer-blind, placebo-controlled expansion study intended to infer the effectiveness of 
messenger RNA [mRNA]-1273 in children aged 6 months to < 12 years. The study population 
will be divided into 3 age groups (6 years to < 12 years, 2 years to < 6 years, and 6 months to 
< 2 years), and up to 3 dose levels (25, 50, and 100 µg) of mRNA-1273 will be evaluated (and 
a third dose or an optional booster of 10 or 25 µg). 
The study will be conducted in 3 parts. Part 1 of the study will be open-label and consist of 
dose-escalation and age de-escalation in approximately 1,275 participants to select the dose for 
each age group with the highest number enrolled in the oldest age group. Part 2 of the study 
will be a placebo-controlled observer-blind evaluation of the selected dose in up to 
12,000 participants (up to 4,000 participants each in the 6 years to < 12 years, 2 years to 
< 6 years, and the 6 months to < 2 years of age groups). Part 3 will be an open-label alternative 
dosing assessment in approximately 300 participants in the 6 year to < 12 year old age group 
to assess reactogenicity and immunogenicity of a lower dose regimen. No participants in Part 
1 will participate in Part 2 or Part 3 of the study, and no participant in Part 2 will participate in 
Part 3 of the study. 
In order to expedite the study of the safety of mRNA-1273 in school-aged children 6 years to 
< 12 years of age; Part 1 will enroll a total of approximately 375 participants per dose (both at 
the 50 and 100 µg dose levels) in this age group (6 years to < 12 years). The first 75 of these 
participants per dose will be included in the safety evaluation for dose-escalation and age de-
escalation as well as the immunogenicity assessment needed for dose selection, as applicable. 
Additionally, approximately 300 participants per dose will be enrolled to assess for any 
adverse event (AE) occurring at 1% or higher. The sample size for Part 2 in this age group 
(6 years to < 12 years) will be adjusted to approximately 1700 participants. Conversely, 
approximately 75 participants in the middle age group (2 years to < 6 years) will be enrolled 
per dose in Part 1 for safety and dose selection and Part 2 will utilize the dose selected in Part 

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1 to inform on AEs occurring at a frequency of 1% or greater. In the youngest age group (6 
months to < 2 years), approximately 150 participants will be enrolled per dose in Part 1 for 
safety and dose selection and Part 2 will utilize the dose selected in Part 1 to inform on AEs 
occurring at a frequency of 1% or greater. 
The study will begin with the oldest age group (6 years to < 12 years) and age de-escalate as 
described under Study Progression. Each age group will begin with Part 1 and may advance to 
Part 2 and Part 3 independently. 
The mRNA-1273 investigational vaccine or placebo will be administered as 2 intramuscular 
(IM) injections approximately 28 days apart for Part 1 and Part 2. For Part 3, the mRNA-1273 
investigational vaccine will be administered as 3 IM injections approximately 28 days apart 
for the 2 doses of primary series followed by a third dose at least 3 months and up to 5 months 
after receipt of the second dose of the primary series. The mRNA-1273 dose levels that will be 
evaluated in each age group in Part 1, Part 2 and Part 3 of the study are given in the below 
table. 
Age 
Group 
Part 1 
Part 2 
Part 3 
mRNA-
1273 
25 µg 
mRNA-
1273 
50 µg 
mRNA-
1273 
100 µg 
Selected 
Dose Level 
of mRNA-
1273 From 
Part 1 
Placebo 
mRNA-1273 
25 µg 
2 doses of 
primary series 
+a third dose 
(Month 0, 1, 51) 
6 years to 
< 12 years 
 
Study Arm 
1 (n=375)  
Study Arm 
2 (n=375) 
Study Arm 8 
(n=3,000) 
Study Arm 
9 (n=1,000) 
Study Arm 14 
(n = 
approximately 
300) 
2 years to 
< 6 years 
Study 
Arm 7 
(Optional) 
(n=75) 
Study Arm 
3 (n=75) 
Study Arm 
4 (n=75) 
Study 
Arm 10 
(n= up to 
3,000) 
Study Arm 
11 (n= up 
to 1,000) 
 
6 months 
to 
< 2 years 
Study 
Arm 5 
(n=150) 
Study Arm 
6 (n=150) 
 
Study Arm 
12 (n= up to 
3,000) 
Study Arm 
13 (n= up 
to 1,000) 
 
Abbreviations: mRNA = messenger RNA. 
1. Four months post-Dose 2 ± 28 days (at least 3 months and up to 5 months after Dose 2) 
Optional Booster Doses: 
Per Amendment 7, Part 1 (all ages) and 6 to < 12 year old Part 2 participants will be offered an 
optional booster dose of mRNA-1273 lower than the chosen primary series for each age group 
(see table below), at least 6 months after Dose 2 of mRNA-1273 (Part 1 participants, and Part 
2 participants in Study Arm 8; Part 2 placebo recipients from Study Arm 9 who crossed over 

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to mRNA-1273 after unblinding). 
In Amendment 9, all participants in all age groups in Part 1 and Part 2 who have not yet 
received a booster dose will be offered a booster dose with mRNA-1273.214 (instead of 
mRNA-1273). 
Age at Time of Booster 
Booster Dose 
(mRNA-1273 or 
mRNA-1273.214) 
6 to 12 years 
25 µg 
2 to < 6 years 
10 µg 
6 months to < 2 years 
10 µg 
Part 1 of the study will be open label. The study will begin with enrollment of approximately 
375 participants in the 6 years to < 12 years age group (Study Arm 1) and dosing with 50 µg 
of mRNA-1273. After at least 75 participants in Study Arm 1 have completed Day 8 (1 week 
after Dose 1 of mRNA-1273 50 µg), an internal safety team (IST) will review the available 
safety data and provide a recommendation whether to escalate the dose to 100 µg in the 
6 years to < 12 years age group (Study Arm 2; n = 375) and independently whether to begin 
dosing at the 50-µg dose level in the 2 years to < 6 years age group (Study Arm 3; n = 75). 
After at least 75 participants in Study Arm 1 reach Day 36 (1 week after Dose 2 of 
mRNA-1273 50 µg), the IST will again review the available safety data and provide a 
recommendation whether to administer Dose 2 of mRNA-1273 100 µg in Study Arm 2 and 
whether to administer Dose 2 of mRNA-1273 50 µg in Study Arm 3. Simultaneously, the 
enrollment- of the remaining 300 planned participants for both Study Arm 1 and Study Arm 2 
will be ongoing. A preliminary safety and immunogenicity data review of Study Arm 1, and 
Study Arm 2 as applicable, will aid in the selection of a dose level for Part 2. Once all or a 
subset of participants from each of Study Arms 1 and 2 reach Day 57 (1 month after Dose 2 of 
mRNA-1273), an interim analysis may be conducted to review the safety and immunogenicity 
data. Cumulative safety data for approximately 300 participants at the selected dose level will 
be reviewed by the Data Safety Monitoring Board (DSMB) before enrollment in Part 2, and 
the DSMB safety review recommendation will enable the expansion of the 6 years to 
< 12 years age group (Part 2) to receive either mRNA-1273 at the selected dose level (Study 
Arm 8; n = 3,000) or placebo (Study Arm 9; n = 1,000). The primary analysis of 
immunogenicity in Part 2 for Study Arm 8 (mRNA-1273 recipients) will be conducted after 
the pre-specified Immunogenicity Subset of participants reaches Day 57, and safety analysis 
will be conducted after a subset or all participants in Study Arms 8 and 9 reach Day 57. 
Part 3 of the study will be open label. A total of approximately 300 participants in the 6 year to 
< 12 year old age group will be enrolled to receive 3 total doses of mRNA-1273 at 25 µg, 
given as the primary series doses at Day 1 and Day 29 followed by a third dose on Day 149/ 

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(BD)-Day 1 (at least 3 months and up to 5 months after the second dose in the primary series). 
The primary analysis of immunogenicity and safety in Part 3 for Study Arm 14 will be 
conducted after all treated participants reach Day 57 (for primary series). The primary analysis 
of immunogenicity and safety for the third dose will be conducted after all participants who 
received a third dose reach Day 177/BD-Day 29. 
For the middle age group (2 years to < 6 years), progression in Part 1 will be as follows: After 
75 participants in Study Arm 3 have completed Day 8 (1 week after Dose 1 of mRNA-1273 
50 µg), an IST will review the available safety data and provide a recommendation whether to 
escalate the dose to 100 µg in the 2 years to < 6 years age group (Study Arm 4; n = 75) and 
whether to begin dosing in the 6 months to < 2 years age group at the 25-µg dose level (Study 
Arm 5; n = 150). After the 75 participants in Study Arm 3 reach Day 36 (1 week after Dose 2 
of mRNA-1273 50 µg), the IST will review the available safety data and provide a 
recommendation whether to administer Dose 2 of mRNA-1273 100 µg in Study Arm 4 and 
whether to administer Dose 2 of mRNA-1273 25 µg in Study Arm 5. An optional Arm 7 may 
be enrolled in this age group (approximately 75 participants) at the 25-µg dose if the 100-µg 
dose is eliminated at any point during dose-escalation process, to maintain dose ranging for 
this age group. A preliminary safety and immunogenicity data review of all applicable arms 
will aid in the selection of a dose level for Part 2. Once all or a subset of participants in all 
applicable arms reach Day 57 (1 month after Dose 2 of mRNA-1273), an interim analysis may 
be conducted to review safety and immunogenicity data. A preliminary safety and 
immunogenicity data review of all applicable arms will aid in the selection of a dose level for 
Part 2 and for expansion of the 2 years to < 6 years age group (Part 2) to receive either 
mRNA-1273 at the selected dose level (Study Arm 10; n = up to 3,000) or placebo (Study 
Arm 11; n = up to 1,000). The primary analysis of immunogenicity in Part 2 for Study Arm 10 
(mRNA-1273 recipients) will be conducted after a pre-specified Immunogenicity Subset of 
participants reaches Day 57, and safety analysis will be conducted after a subset or all 
participants in Study Arms 10 and 11 reach Day 57. 
For the youngest age group (6 months to < 2 years) progression in Part 1 will be as follows: In 
Study Arm 5, after 150 participants have completed Day 8 (1 week after Dose 1 of 
mRNA-1273 25 µg), an IST will review the available safety data and provide a 
recommendation whether to escalate the dose to 50 µg (Study Arm 6; n = 150). After the 
150 participants in Study Arm 5 reach Day 36 (1 week after Dose 2 of mRNA-1273 25 µg), 
the IST will review the available safety data and provide a recommendation whether to 
administer Dose 2 of mRNA-1273 50 µg in Study Arm 6. Once all or a subset of participants 
in Study Arms 5 and 6 reach Day 57 (1 month after Dose 2 of mRNA-1273), an interim 
analysis may be conducted to review the tolerability and immunogenicity data at each dose 

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level. A preliminary safety and immunogenicity data review of Study Arm 5 and Study Arm 6, 
as applicable, will aid in the selection of a dose level for Part 2 and allow for expansion of the 
6 months to < 2 years age group (Part 2) to receive either mRNA-1273 at the selected dose 
level (Study Arm 12; n = up to 3,000) or placebo (Study Arm 13; n = up to 1,000). The 
primary analysis of immunogenicity in Part 2 for Study Arm 12 (mRNA-1273 recipients) will 
be conducted after the pre-specified Immunogenicity Subset of participants reaches Day 57, 
and safety analysis will be conducted after a subset or all participants in Study Arms 12 and 13 
reach Day 57. 
In general, if a decision is made not to proceed with administration of the higher dose and/or 
the second injection at a given dose level (eg, due to safety concerns), the participants 
scheduled to receive the higher dose may receive a lower dose, and the participants who had 
received the higher dose level as their first injection will likely be given the next lower dose 
level that was tolerated for their second injection. The dose level not tolerated in the older age 
group will not be administered in any of the younger age groups. Within an age group, if one 
of the dose levels is found to have an unacceptable tolerability profile, the age group may 
progress to Part 2 at a lower dose level. 
Part 1 and Part 2 participants who have not yet received a booster dose with mRNA-1273, nor 
a non-study vaccine booster dose will be offered an optional booster dose of mRNA-1273.214 
lower than the chosen primary series for each age group, at least 3 months after Dose 2 of 
mRNA-1273. 
The final analysis will be performed when participants (Study Arms 1 to 14) conclude the 
safety follow-up at 12 months after their last dose (either Dose 2 or booster dose). 
The goal of the study is to support an indication for use of mRNA-1273 50 or 100 µg IM, 
given as 2 injections, approximately 28 days apart (pandemic dosing) or for the use of mRNA-
1273 25 µg given as 3 injections, approximately 28 days (primary series) and at least 3 months 
and up to 5 months (third dose) apart (lower dosing) in the 6 years to < 12 years age group; 
mRNA-1273 25, 50, or 100 µg IM, given as 2 injections, approximately 28 days apart in the 
2 years to < 6 years age group; and mRNA-1273 25 or 50 µg IM, given as 2 injections, 
approximately 28 days apart in the 6 months to < 2 years age group. In addition, the study will 
provide support for the indication of a booster dose, given at the lower dosage level of the 
primary series, at least 6 months, as applicable, after Dose 2. The basis for demonstrating 
vaccine effectiveness is proposed to be met by measuring serum antibody responses in the 
study participants. The approach to inferring vaccine effectiveness will depend on whether an 
accepted serum antibody threshold conferring protection against coronavirus disease 2019 
(COVID-19) has been established. If an antibody threshold of protection has been established, 
effectiveness will be inferred based on the proportion of study participants with serum 

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antibody levels (on Day 57) that meet or exceed the antibody threshold. If an antibody 
threshold of protection has not been established, effectiveness will be inferred by 
demonstrating noninferiority for each age group (6 years to < 12 years, 2 years to < 6 years, 
and 6 months to < 2 years in Study P204) compared with young adult (18 to 25 years of age) 
participants enrolled in the ongoing clinical endpoint efficacy trial (Study P301) by both 
geometric mean (GM) values and seroresponse rate (SRR). 
This study in children 6 months to < 12 years of age will monitor all participants for a total of 
12 months following the second dose of vaccine or placebo, or 12 months following their 
booster dose or third dose, if applicable. Safety assessments will include solicited adverse 
reactions (ARs) 7 days after each injection (ie, the day of injection and 6 subsequent days), 
unsolicited AEs (28 days after each injection), and medically attended adverse events 
(MAAEs), serious adverse events (SAEs), and adverse events of special interest (AESIs) 
(including multisystem inflammatory syndrome in children [MIS-C] and myocarditis and/or 
pericarditis) through the entire study period. 
Blood samples will be collected from participants in Part 1, Part 2, and Part 3 of the study for 
assessment of immunogenicity. If a Day 1 (baseline) blood sample cannot be obtained in either 
Part 1, Part 2, or Part 3, the participant will be considered either a screen failure due to 
inability to satisfy inclusion criterion 3 or could be rescheduled for rescreening. Participants 
may be rescreened 1 time, either within the same screening period for Part 1 or Part 2 or in a 
new screening period of Part 2 or Part 3 if the initial screening was in Part 1 or Part 2, 
respectively. If the participant is rescreened and a blood sample still cannot be obtained, then 
he/she will be considered a screen failure due to inability to satisfy inclusion criterion 3. Blood 
samples will also be tested for the development of antibodies directed against nonvaccine 
antigen (eg, antibodies against the nucleocapsid protein), which will signify infection with 
severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The incidence of SARS-
CoV-2 infection among vaccine recipients and placebo recipients will be compared to assess 
the potential for mRNA-1273 to reduce the rate of infection in vaccine recipients. In addition, 
all participants will be monitored for symptoms of COVID-19 and scheduled for illness visits 
if concerning symptoms occur, and a nasal swab will be collected at the illness visit while Part 
2 remains blinded for any age group. Once the trial is unblinded for all age groups and thus no 
placebo comparator group is available going forward, illness visits for COVID-19 symptoms 
or exposures and convalescent visits will no longer be required. 

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Safety Oversight: 
The contract research organization’s medical monitor, the Sponsor’s medical monitor, and the 
individual study site investigators will monitor safety throughout the study. 
Internal Safety Team 
An IST will review safety data throughout Part 1 of the study. For Part 1 dose escalation and 
age de-escalation, based on the review of all available safety data through at least Day 8 
(1 week after Dose 1 of mRNA-1273) for at least 75 participants at each dose level within the 
6 years to < 12 years and 2 years to < 6 years age group, the IST will recommend whether 
dose escalation and age de-escalation are appropriate. This process will then be repeated for all 
participants in the 25 and 50 µg dose levels within the lower age group of 6 months to 
< 2 years of age. An IST review of all available safety data through at least Day 36 (1 week 
after Dose 2 of mRNA-1273 at each dose level) of at least 75 participants will be required 
prior to the administration of the second injection of the next higher dose. In addition, the IST 
will escalate any safety concerns to the DSMB. The frequency of IST meetings will be 
described in more detail in the IST charter. 
Data Safety Monitoring Board 
Safety oversight will be under the direction of a DSMB composed of external independent 
consultants with relevant expertise. Members of the DSMB will be independent from study 
conduct and free of conflict of interest. The DSMB will meet at pre-specified timepoints 
during the study to assess safety throughout study conduct. For the 6 years to < 12 years age 
group, the DSMB will review cumulative safety data for approximately 300 participants 
enrolled at the selected dose level in Part 1 before enrollment begins in Part 2. For both the 
middle age group (2 years to < 6 years) and the youngest age group (6 months to < 2 years) the 
DSMB will review cumulative safety data in both younger age groups (2 years to < 6 years; 6 
months to < 2 years) combined and at all dose levels administered in Part 1 before start of Part 
2 (blinded phase) for each age group. The DSMB will operate under the rules of an approved 
charter that will be written and reviewed at the organizational meeting of the DSMB. Details 
regarding the DSMB composition, responsibilities, procedures, and frequency of data review 
will be defined in its charter. 
If any of the study pause rules are met, the Sponsor will immediately suspend further 
enrollment and/or study dosing and the DSMB will convene on an ad hoc basis. The DSMB 
will review all available unblinded study data (as applicable) to help adjudicate any potential 
study pauses and make recommendations on further study conduct, including requesting 
additional information, recommending stopping the study, recommending changes to study 
conduct and/or the protocol, or recommending additional operational considerations due to 

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safety issues that arise during the study. 
The Cardiac Event Adjudication Committee (CEAC) consisting of pediatric and adult 
cardiologists will review suspected cases of myocarditis, pericarditis, or myopericarditis to 
determine if they meet US Centers for Disease Control and Prevention (CDC) criteria of 
“probable” or “confirmed” event, and to assess severity and enable the DSMB to make 
recommendations to the Sponsor to continue vaccine dosing. The CEAC will operate under the 
rules of an approved charter that will be written and reviewed at the organizational meeting of 
the CEAC. Details regarding the CEAC composition, responsibilities, procedures, and 
frequency of data review will be defined in its charter. 
In Part 2 (blinded phase), the Sponsor’s medical monitor may escalate to the DSMB chair if 
any safety concerns are identified, as described in the DSMB charter. 
Study Duration: The study duration for each participant will be variable depending on 
whether they choose to receive a booster (or third dose in Part 3) or not; without a booster 
dose, it will be approximately 14 months, which includes 1 month for screening (Day -28 to 
Day -1), 1 month for dosing (on Day 1 and Day 29), and 12 months of follow-up after the 
second dose to monitor for safety, tolerability, reactogenicity, immunogenicity, and efficacy. 
With a booster dose given, the study duration will be up to 24 months. 
Number of Participants: 
Part 1: Approximately 1,275 participants (approximately 750 participants in the 6 years to 
< 12 years age group, approximately 225 participants 2 years to < 6 years age group, and 
approximately 300 participants in the 6 months to < 2 years age group). 
Part 2: Up to 12,000 participants (up to 3,000 participants each exposed to mRNA-1273 and 
1,000 participants exposed to placebo in the 6 years to < 12 years, 2 years to < 6 years, and 6 
months to < 2 years age groups). 
Part 3: Approximately 300 participants in the 6 year to < 12 year old age group. 
Study Eligibility Criteria: 
Inclusion Criteria: 
Participants are eligible to be included in the study only if all the following criteria apply: 
1. The participant is male or female, 6 months to < 12 years of age at the time of 
consent/assent (Screening Visit), who is in good general health, in the opinion of the 
investigator, based on review of medical history and screening physical examination. 
2. If the participant has a chronic disease (eg, asthma, diabetes mellitus, cystic fibrosis, 

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human immunodeficiency virus [HIV] infection), the disease should be stable, per 
investigator assessment, so that the participant can be considered eligible for inclusion. 
Stable diseases are those which have had no change in their status or in the medications 
required to control them in the 6 months prior to Screening Visit. 
Note: a change in medication for dose optimization (eg, insulin dose changes), change 
within class of medication, or reduction in dose are not considered signs of instability. 
3. In the investigator’s opinion, the parent(s)/legally authorized representative(s) 
understand and are willing and physically able to comply with protocol-mandated 
follow-up, including all procedures, and provide written informed consent and 
participants are willing to provide assent. 
4. The participant is 2 years or older and has a body mass index at or above the third 
percentile according to World Health Organization (WHO) Child Growth Standards at 
the Screening Visit. 
The participant is less than 2 years of age and the participant’s height and weight are 
both at or above the 3rd percentile according to WHO Child Growth Standard at the 
Screening Visit. 
5. Female participants of nonchildbearing potential may be enrolled in the study. 
Nonchildbearing potential is defined as premenarche. 
Special inclusion criteria for female participants who have reached menarche: 
6. Female participants of childbearing potential may be enrolled in the study if the 
participant fulfills all of the following criteria: 
• Has a negative pregnancy test at Screening. Pregnancy test will be performed if 
deemed appropriate by the investigator. 
• Has practiced adequate contraception or has abstained from all activities that could 
result in pregnancy for at least 28 days prior to the first injection (Day 1). 
• Has agreed to continue adequate contraception or abstinence through 3 months 
following the second injection (Day 29) and the third dose in Part 3 
(Day 149/BD-Day 1). 
• Is not currently breastfeeding. 
Adequate female contraception is defined as abstinence or consistent and correct use of 
a US Food and Drug Administration-approved contraceptive method in accordance 
with the product label. 

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Special inclusion criteria for children 6 months to < 12 months of age 
7. The participant was born at full-term (≥ 37 weeks gestation) with a minimum birth 
weight of 2.5 kg. 
Exclusion Criteria: 
Participants will be excluded from the study if any of the following criteria apply: 
1. Has a known history of SARS-CoV-2 infection within 2 weeks prior to administration 
of investigational product (IP) or known close contact with anyone with laboratory-
confirmed SARS-CoV-2 infection or COVID-19 within 2 weeks prior to 
administration of IP. 
2. Is acutely ill or febrile 24 hours prior to or at the Screening Visit. Fever is defined as a 
body temperature ≥ 38.0°C/≥ 100.4°F. Participants who meet this criterion may have 
visits rescheduled within the relevant study visit windows. Afebrile participants with 
minor illnesses can be enrolled at the discretion of the investigator. 
3. Has previously been administered an investigational or approved CoV (eg, 
SARS-CoV-2, SARS-CoV, Middle East respiratory syndrome CoV) vaccine. 
4. Has undergone treatment with investigational or approved agents for prophylaxis 
against COVID-19 (eg, receipt of SARS-CoV-2 monoclonal antibodies) within 
6 months prior to enrollment. 
5. Has a known hypersensitivity to a component of the vaccine or its excipients. 
Hypersensitivity includes, but is not limited to, anaphylaxis or immediate allergic 
reaction of any severity to a previous dose of messenger RNA COVID-19 vaccine or 
any of its components (including polyethylene glycol [PEG] or immediate allergic 
reaction of any severity to polysorbate). 
6. Has a medical or psychiatric condition that, according to the investigator’s judgment, 
may pose additional risk as a result of participation, interfere with safety assessments, 
or interfere with interpretation of results. 
7. Has a history of a diagnosis or condition that, in the judgment of the investigator, may 
affect study endpoint assessment or compromise participant safety, specifically the 
following: 
• Congenital or acquired immunodeficiency, excluding HIV infection, as described in 
Inclusion Criteria 2 
• Chronic hepatitis or suspected active hepatitis 

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• A bleeding disorder that is considered a contraindication to IM injection or 
phlebotomy 
• Dermatologic conditions that could affect local solicited AR assessments 
• Any prior diagnosis of malignancy (excluding nonmelanoma skin cancer) 
• Febrile seizures* 
*In Part 2 and Part 3 of the study, a history of a single, simple febrile seizure is 
allowed for children 6 years and older. 
8. Has received the following: 
• Any routine vaccination with inactivated or live vaccine(s) within 14 days prior to 
first vaccination or plans to receive such a vaccine through 14 days following the 
last study vaccination. 
• Note: This excludes influenza vaccine that may be given, however, not 
within 14 days prior to or post-Dose 1 or Dose 2. If a participant receives an 
influenza vaccine, this should be captured within the concomitant 
medication electronic case report form (eCRF). 
• Systemic immunosuppressants or immune-modifying drugs for > 14 days in total 
within 6 months prior to the day of enrollment (for corticosteroids, ≥ 1 mg/kg/day 
or ≥ 10 mg/day prednisone equivalent, if participant weighs > 10 kg). Participants 
may have visits rescheduled for enrollment if they no longer meet this criterion 
within the Screening Visit window. Inhaled, nasal, and topical steroids are allowed. 
• Intravenous or subcutaneous blood products (red cells, platelets, immunoglobulins) 
within 3 months prior to enrollment. 
9. Has participated in an interventional clinical study within 28 days prior to the 
Screening Visit or plans to do so while participating in this study. 
10. Is an immediate family member, or household contact, of an employee of the study site 
or Moderna or someone otherwise directly involved with the conduct of the study. As 
applicable, family members/household contacts of employees of the larger institution 
or affiliated private practice not part of the study site may be enrolled. 
 
 
 

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Study Treatment: 
Investigational Product: 
The term IP refers to mRNA-1273 (10, 25, 50, and 100 µg) vaccine or mRNA-1273.214 (10 
and 25 µg) or placebo (0.9% sodium chloride) in this study. 
mRNA-1273.214 is a bivalent vaccine containing mRNA-1273 and mRNA-1273.529 co 
formulated at a 1:1 ratio. mRNA-1273.214 injection is provided as a sterile liquid and is a white 
to off white dispersion at a concentration of 
 mg/mL in 20 mM Tris buffer with sucrose at 
pH 7.5. 
mRNA-1273 is a lipid nanoparticle (LNP) dispersion of an mRNA that encodes the prefusion 
stabilized S protein of SARS-CoV-2 formulated in LNPs composed of 4 lipids (1 proprietary 
and 3 commercially available): the proprietary ionizable lipid heptadecan-9-yl 
8-((2hydroxyethyl)(6-oxo-6-(undecyloxy)hexyl)amino)octanoate (SM102); cholesterol; 
1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC); and 1-monomethoxypolyethyleneglycol-
2,3-dimyristylglycerol with PEG of average molecular weight 2000 
(1-monomethoxypolyethyleneglycol-2,3-dimyristylglycerol polyethylene glycol 2000 
[PEG2000-DMG]). mRNA-1273 injection is provided as a sterile liquid for injection and is a 
white to off-white dispersion at a concentration of 
 mg/mL in 20 mM Tris buffer containing 
87 mg/mL sucrose and 4.3 mM sodium acetate at pH 7.5. 
mRNA-1273.529 contains mRNA CX-031302 encoding for the S-2P of the SARS-CoV-2 
Omicron variant (B.1.1.529). mRNA-1273 contains mRNA CX-024414 encoding for the S-2P 
of Wuhan Hu 1. The mRNAs are formulated in a mixture of 4 lipids common to the Sponsor’s 
mRNA vaccine platform: SM-102, cholesterol, DSPC, and PEG 2000 DMG. 
Mode of Administration: 
In Part 1 and Part 2, each participant will receive 2 doses of IP by IM injection approximately 
28 days apart (Day 1 and Day 29). Part 1 and Part 2 participants who did not previously 
receive any booster doses will be offered a booster dose of IP by IM injection at least 3 
months after Dose 2. 
For Part 3, each participant will receive 3 doses of IP by IM injections approximately 28 days 
apart for the 2 primary doses of primary series followed by a third dose at least 3 months after 
receipt of the second dose of the primary series (Day 1, Day 29, and Day 149/BD-Day 1). The 
IM injections will be administered into the deltoid muscle or anterolateral thigh (per 
investigator’s discretion). 
 
CCI
CCI

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Procedures and Assessments: 
Safety Assessments: 
Safety assessments will include monitoring and recording of the following for each participant 
as applicable per SoA. 
• Solicited local and systemic ARs that occur during the 7 days following each injection 
(ie, the day of injection and 6 subsequent days). Solicited ARs will be recorded daily 
using electronic diaries (eDiary). 
• Unsolicited AEs observed or reported during the 28 days following each injection (ie, 
the day of injection and 27 subsequent days). 
• AEs leading to discontinuation from dosing and/or study participation from Day 1 
through the last day of study participation. 
• MAAEs from first dose on Day 1 through the entire study period. 
• SAEs from first dose on Day 1 through the entire study period. 
• AESIs including MIS-C and myocarditis and/or pericarditis, through the entire study 
period. 
• Physical examination findings. 
• Assessments for SARS-CoV-2 infection from Day 1 through study completion. 
• Details of all pregnancies in female participants will be collected after the start of study 
treatment and until the end of their participation in the study. 
Blood Collections for Immunogenicity Assessments and Biomarker Samples: 
The following analytes will be measured in blood samples for immunogenicity assessments 
and biomarker samples: 
• Serum neutralizing antibody (nAb) titer against SARS-CoV-2 as measured by 
pseudovirus and/or live virus neutralization assays. 
• Serum binding antibody (bAb) titer as measured by enzyme-linked immunosorbent 
assay specific to the SARS-CoV-2 S protein. 
• Serologic markers for SARS-CoV-2 infection using a nonvaccine antigen-based blood 
test. 
Efficacy Assessments: 
Vaccine effectiveness for children 6 months to < 12 years of age will be inferred based on 

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serum antibody responses obtained on Day 57 (28 days after the second injection of 
mRNA-1273). Inference will be based on assessing the antibody responses against the 
following: 
1.  If available at the time of analysis, antibody responses will be assessed against an 
accepted serum antibody threshold conferring protection against COVID-19. 
2.  If an accepted threshold of protection is not available, noninferiority of the GM value 
of serum antibody and SRR of children 6 months old to < 12 years old (Study P204) 
compared with the GM value of serum antibody and SRR from young adults (18 to 25 
years of age) enrolled in the ongoing clinical endpoint efficacy trial (Study P301) will 
be assessed. 
Statistical Methods: 
Hypothesis Testing: 
If an accepted antibody threshold of protection against COVID-19 is established for the 
primary immunogenicity endpoint, the null hypothesis is that the percentage of participants on 
mRNA-1273 with serum antibody above the established threshold at Day 57 is ≤ 70% 
(ie, H0: percentage of participants on mRNA-1273 with serum antibody at Day 57 above the 
established threshold ≤ 70%). 
For each age group, the study will be considered to meet the immunogenicity endpoint if the 
95% confidence interval (CI) of percentage of participants on mRNA-1273 rules out 70% 
(lower bound of the 95% CI is > 70%). 
The null hypotheses may be updated when the information on an acceptable antibody 
threshold becomes available. In this case, the null hypothesis update will be provided in the 
statistical analysis plan (SAP). 
If an accepted serum antibody threshold of protection against COVID-19 is not available for 
the primary immunogenicity endpoint, immune response as measured by GM value and SRR 
in each age group based on Day 57 antibody levels will be compared with Day 57 antibody 
levels from young adults (18 to 25 years of age) in Study P301. Noninferiority tests of 2 null 
hypotheses based on 2 coprimary endpoints will be performed, respectively. 
Part 1 or 2 Hypothesis Testing for Primary Series in Each Age Group 
Coprimary endpoint 1: antibody GM value at Day 57 
The null hypothesis H10: immunogenicity response to mRNA-1273, as measured by antibody 
GM value at Day 57, is inferior in children (in age groups 6 months to < 2 years, 2 years to 

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< 6 years, and 6 years to < 12 years) compared with that in young adults (18 to 25 years of 
age) using mRNA-1273 Study P301 data. 
The noninferiority in antibody GM value in an age group in children compared with that in 
young adults (18 to 25 years of age) is demonstrated by meeting both success criteria: 
- 
The lower bound of the 95% CI of the geometric mean ratio (GMR) ruling out 0.67 
(lower bound ≥ 0.67) using a noninferiority margin of 1.5, AND 
- 
The GMR point estimate ≥ 0.8 (minimum threshold). 
The GMR is the ratio of the GM value of SARS-CoV-2-specific antibody in children in an 
age group receiving mRNA-1273 in this Study P204 compared with the GM value of 
young adults (18 to 25 years of age) receiving mRNA-1273 in Study P301 at Day 57. 
Coprimary endpoint 2: antibody seroresponse rate at Day 57 
A definition of seroresponse will be provided in the SAP based on forthcoming information 
about assay performance. 
The null hypothesis H20: immunogenicity response to mRNA-1273 as measured by SRR at 
Day 57 is inferior in children compared with that in young adults (18 to 25 years of age) in 
Study P301. 
The noninferiority in SRR in an age group in children compared with that in young adults (18 
to 25 years of age) is demonstrated by meeting both success criteria: 
- 
The lower bound of the 95% CI of the SRR difference ruling out -10% (ie, lower 
bound ≥ -10%) using the noninferiority margin of 10%, AND 
- 
The SRR difference point estimate ≥ -5% (minimum threshold) 
The SRR difference is defined as the SRR in children receiving mRNA-1273 minus the 
SRR in young adults of 18 to 25 years of age receiving mRNA-1273 from Study P301. 
The study would be considered to meet the primary immunogenicity endpoint in an age group 
if the noninferiority in the age group compared with the young adults (18 to 25 years of age) is 
demonstrated based on both coprimary endpoints. 
Part 1 or Part 2 Hypothesis Testing for mRNA-1273 Booster Dose 
Booster dose coprimary endpoint 1: antibody GM at BD-Day 29 
The null hypothesis H10: immunogenicity response to mRNA-1273 booster dose as measured 
by Ab GM at BD-Day 29 in children in Study P204 is inferior compared with Ab GM that at 
Day 57 (28 days after Dose 2) in the primary series of mRNA-1273 in adults (≥18 to 25 years 
of age) in Study P301. 

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The noninferiority in Ab GM at BD-Day 29 in children receiving mRNA-1273 as a booster 
dose in Study P204 compared with Ab GM at Day 57 in the primary series in adults (18 to 25 
years of age) in Study P301 will be demonstrated by the GMR 95% CI lower bound ≥ 0.67 
using a noninferiority margin of 1.5. The GMR is defined as the ratio of GM value of Ab at 
BD-Day 29 in Study P204 compared with Ab GM value at Day 57 (28 days after Dose 2) 
following the primary series of mRNA-1273 in Study P301. 
Booster dose coprimary endpoint 2: antibody seroresponse rate at BD-Day 29 
The null hypothesis H20: immunogenicity response to mRNA-1273 booster dose as measured 
by SRR at BD-Day 29 in children in Study P204 is inferior compared with SRR at Day 57 
(28 days after Dose 2) following the primary series of mRNA-1273 in adults (18 to 25 years of 
age) in Study P301. 
The noninferiority in SRR at BD-Day 29 in children receiving mRNA-1273 as a booster dose 
in Study P204 compared with SRR at Day 57 (28 days after Dose 2) following the primary 
series of mRNA-1273 will be demonstrated by the SRR 95% CI lower bound ≥ -10% using 
the noninferiority margin of 10%. The SRR difference is defined as the SRR at BD-Day 29 in 
Study P204 minus the rate at Day 57 (28 days after Dose 2) following the primary series of 
mRNA-1273 in adults in Study P301. The SRR is defined as a titer change from baseline (pre-
Dose 1) below the lower limit of quantification (LLOQ) to ≥ 4 × LLOQ, or at least a 4-fold 
rise if baseline is ≥ LLOQ. 
Booster dose primary immunogenicity objective for an age group in Part 2 will be considered 
to be met if the noninferiority in an age group compared with the adults (18 to 25 years of age) 
is demonstrated based on both coprimary endpoints. 
Part 3 Hypothesis Testing for Primary Series 
Primary series coprimary endpoint 1: antibody GM value at Day 57 
The null hypothesis H10: immunogenicity response to mRNA-1273, as measured by antibody 
GM value at Day 57, is inferior in children compared with that in adults (≥ 18 years of age) 
using mRNA-1273 Study P301 data. 
The noninferiority in antibody GM value in children in Part 3 compared with that in adults 
(≥ 18 years of age) is demonstrated by meeting the following success criterion: 
• The lower bound of the (1-alpha) CI of the GMR ruling out 0.67 (lower bound ≥ 0.67) 
using a noninferiority margin of 1.5. 
The 1-alpha can be 97.5% or 95% depending on the alpha level of 0.025 or 0.05 used for the 
hypothesis testing. The GMR is the ratio of the GM value of SARS-CoV-2-specific antibody 

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in children receiving mRNA-1273 in this Study P204 compared with the GM value of adults 
(≥ 18 years of age) receiving mRNA-1273 in Study P301 at Day 57. 
Primary series coprimary endpoint 2: antibody seroresponse rate at Day 57 
The null hypothesis H20: immunogenicity response to mRNA-1273 as measured by SRR at 
Day 57 is inferior in children compared with that in adults (≥ 18 years of age) in Study P301. 
The noninferiority in SRR in children receiving mRNA-1273 in Part 3 compared with that in 
adults (≥ 18 years of age) is demonstrated by meeting the following success criterion: 
• The lower bound of the (1-alpha) CI of the SRR difference ruling out -10% (ie, lower 
bound ≥ -10%) using the noninferiority margin of 10%. 
The 1-alpha can be 97.5% or 95% depending on the alpha level of 0.025 or 0.05 used for the 
hypothesis testing. The SRR difference is defined as the SRR in children receiving mRNA-
1273 minus the SRR in adults of ≥ 18 years of age receiving mRNA-1273 from Study P301. 
Part 3 primary series primary immunogenicity objective will be considered to be met if the 
noninferiority in children compared with the adults (≥ 18 years of age) is demonstrated based 
on both coprimary endpoints. 
Part 3 Hypothesis Testing for Third Dose 
Third dose coprimary endpoint 1: antibody GM at BD-Day 29 
The null hypothesis H10: immunogenicity response to mRNA-1273 third dose as measured by 
Ab GM at BD-Day 29 in children in Study P204 is inferior compared with Ab GM that at Day 
57 (28 days after Dose 2) in the primary series of mRNA-1273 in adults (≥ 18 years of age) in 
Study P301. 
The noninferiority in Ab GM at BD-Day 29 in children receiving mRNA-1273 as a third dose 
in Study P204 compared with Ab GM at Day 57 in the primary series in adults (≥ 18 years of 
age) in Study P301 will be demonstrated by the GMR (1-alpha) CI lower bound ≥ 0.67 using a 
noninferiority margin of 1.5, where the 1-alpha can be 97.5% or 95% depending on the alpha 
level of 0.025 or 0.05 used for the hypothesis testing. The GMR is defined as the ratio of GM 
value of Ab at BD-Day 29 in Study P204 compared with Ab GM value at Day 57 (28 days 
after Dose 2) following the primary series of mRNA-1273 in Study P301. 
Third dose coprimary endpoint 2: antibody seroresponse rate at BD-Day 29 
The null hypothesis H20: immunogenicity response to mRNA-1273 third dose as measured by 
SRR at BD-Day 29 in children in Study P204 is inferior compared with SRR at Day 57 

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(28 days after Dose 2) following the primary series of mRNA-1273 in adults (≥ 18 years of 
age) in Study P301. 
The noninferiority in SRR at BD-D29 in children receiving mRNA-1273 as a third dose in 
Study P204 compared with SRR at Day 57 (28 days after Dose 2) following the primary series 
of mRNA-1273 will be demonstrated by the SRR (1-alpha) CI lower bound ≥ -10% using the 
noninferiority margin of 10%, where the 1-alpha can be 97.5% or 95% depending on the alpha 
level of 0.025 or 0.05 used for the hypothesis testing. The SRR difference is defined as the 
SRR at BD-Day 29 in Study P204 minus the rate at Day 57 (28 days after Dose 2) following 
the primary series of mRNA-1273 in adults in Study P301. The SRR is defined as a titer 
change from baseline (pre-Dose 1) below the LLOQ to ≥ 4 × LLOQ, or at least a 4-fold rise if 
baseline is ≥ LLOQ. 
Part 3 third dose primary immunogenicity objective will be considered to be met if the 
noninferiority in the age group compared with the adults (≥ 18 years of age) is demonstrated 
based on both coprimary endpoints. 
Justification of using Immunogenicity Subset of adults (≥ 18 years of age) from Study P301 as 
a comparator for hypothesis testing 
In Phase 3 pivotal Study P301 with more than 30,000 participants enrolled, vaccine efficacy 
(VE) against symptomatic COVID-19 based on adjudication committee assessment starting 
14 days after second injection in the per protocol (PP) Set was demonstrated with VE estimate 
of 93.2% (95% CI: 91.0, 94.8) in adults ≥ 18 years in the final efficacy analysis (04 May 2021 
database lock) in the blinded phase. In a random sample stratified by baseline SARS-CoV-2 
status (negative vs. positive), age group (< 65 vs. ≥ 65 years) and race/ethnicity (minority vs. 
non-minority), there were n=1055 participants ≥ 18 years of age in the PP Immunogenicity 
Subset who received mRNA-1273 100 µg with baseline negative SARS-CoV-2 status. The 
observed pseudovirus neutralizing antibody (PsVNA) ID50 geometric mean titers (GMT) at 
Day 57 was 1081.1 (95% CI: 1019.8, 1146.1) for adults ≥ 18 years in Study P301. 
A separate random subset of young adults 18 to 25 years of age from Study P301 (n=305 in 
the PP Immunogenicity Subset receiving mRNA-1273 100 µg, of which n=296 have PsVNA 
assay results reported at Day 57) was selected for the purpose of immunobridging adolescents 
in Study P203 and children in Study P204 to young adults in Study P301. This subset of young 
adults with observed PsVNA ID50 GMT of 1301.3 (95% CI: 1172.3, 1444.5) at Day 57 was 
planned and used as a comparator in the primary immunogenicity analysis testing the 
noninferiority of immunogenicity in adolescents in Study P203 and children in Study P204. 
The observed Day 57 GMT of 1301.3 in young adults 18 to 25 years is approximately 1.2-fold 
higher compared with 1081.1 in adults ≥ 18 years of age with high VE established (VE 

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estimate of 93.2% [95% CI: 91.0, 94.8]). The data suggest that adults ≥ 18 years of age may 
also be considered as a reference for immunobridging analyses. 
If a comparator age group of adults ≥ 18 years from Study P301 is used in a primary 
immunogenicity noninferiority hypothesis testing for children in Study P204, a sensitivity 
analysis may be performed by using different age group(s) (eg, 18 to 25 years, ≥ 65 years) 
from Study P301 as a comparator. 
Power and Sample Size: 
The initial age groups in Part 1 are for estimation purposes. With approximately 750 
participants (approximately 375 participants at each dose level of mRNA-1273) in the initial 
6 years to < 12 years age group, there is at least a 90% probability to observe at least 1 
participant with an AE at a true AE rate of 1% for a given dose level. In each of the younger 
age groups (2 years to < 6 years and 6 months to < 2 years), the safety assessment will occur 
during the conduct of Part 2 after approximately 375 participants have been exposed to 
mRNA-1273 at the dose level selected for Part 2. 
The sample size in the expansion (Part 2) is considered to be sufficient to support a safety 
database in the pediatric participants 6 months to < 12 years of age. With up to 
3,000 participants each in the 6 years to < 12 years, 2 years to < 6 years, and 6 months to 
< 2 years of age groups exposed to mRNA-1273 at a given dose level in Part 2, the study has 
at least a 95% probability to observe at least 1 participant with an AE at a true 0.1% AE rate 
for a given dose level. 
The sample size in the lower dosing assessment (Part 3) is approximately 300 children 6 years 
to < 12 years of age receiving mRNA-1273 25 µg. There is at least a 90% probability to 
observe at least 1 participant with an AE at a true AE rate of 1% in this group. 
A subset of Full Analysis Set (FAS) participants (Immunogenicity Subset) in each age group 
will be selected for measuring immunogenicity data. The immunogenicity samples of the 
Immunogenicity Subset will be processed, and the analysis of primary immunogenicity 
endpoint will be based on the PP Immunogenicity Subset. 
If a threshold of protection is available, for the primary immunogenicity endpoint, with 
approximately 289 participants on mRNA-1273 in the PP Immunogenicity Subset of an age 
group, there will be at least 90% power to rule out 70% with a 2-sided 95% CI (lower bound 
of the 95% CI > 70%) for the percentage of mRNA-1273 participants exceeding the accepted 
threshold if the true rate of participants exceeding the threshold is 80%. 
If an acceptable antibody threshold of protection against COVID-19 is not available at the 
time of analysis for the primary immunogenicity endpoint, noninferiority tests of the 2 null 

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hypotheses based on the 2 coprimary endpoints will be performed, respectively. The sample 
size calculation for each of the 2 noninferiority tests was performed, and the larger sample size 
was chosen for the study. 
• With approximately 289 participants receiving mRNA-1273 in the PP Immunogenicity 
Subset of each age group in Study P204 and young adults (18 to 25 years of age) in 
Study P301, there will be 90% power to demonstrate noninferiority of the immune 
response, as measured by the antibody GM value, in pediatric population at a 2‑sided 
alpha of 0.05, compared with that in young adults (18 to 25 years of age) in Study 
P301 receiving mRNA‑1273, assuming an underlying GMR value of 1, a 
noninferiority margin of 0.67 (or 1.5), and a point estimate minimum threshold of 0.8. 
The standard deviation of the natural log‑transformed levels is assumed to be 1.5. 
• With approximately 289 participants receiving mRNA-1273 in the PP Immunogenicity 
Subset of each age group in Study P204 and young adults (18 to 25 years of age) in 
Study P301, there will be at least 90% power to demonstrate noninferiority of the 
immune response as measured by SRR in children at a 2-sided alpha of 0.05, compared 
with that in young adults 18 to 25 years of age in Study P301 receiving mRNA-1273, 
assuming SRR of 85% in young adults of 18 to 25 years of age from Study P301, true 
SRR of 85% in children (or true rate difference is 0 compared with young adults from 
Study P301), a noninferiority margin of 10% and a point estimate minimum threshold 
of -5% in SRR difference. 
• In the 1273-P203 interim analysis (data snapshot on 08 May 2021), the observed SRRs 
at Day 57 were high in both 18 to 25 years of age group from Study P301 (98.6% with 
95% CI: 96.6, 99.6) and 12 to17 years of age group (98.8% with 95% CI: 97.0, 99.7), 
based on pseudovirus nAb ID50 titers. For this Study P204, if the true SRRs were 
assumed to be 95% or higher in both 18 to 25 years of age group from Study P301 and 
an age group in children, with between-group true difference within 4%, there will be a 
>90% power to demonstrate noninferiority by SRR in children compared with 18 to 25 
years of age in Study P301, at a 2-sided alpha of 0.05. 
• Assuming approximately 25% of participants in the Immunogenicity Subset in Part 2 
will not meet the criteria to be included in the PP Immunogenicity Subset, 
approximately 528 participants in Part 2 (~396 receiving mRNA-1273 and ~132 
receiving placebo) will be selected for the Immunogenicity Subset from which 
approximately 289 participants on mRNA-1273 will be suitable for the PP 
Immunogenicity Subset in Part 2. 

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• In Part 2 for the booster dose primary immunogenicity analysis in an age group, with 
approximately 289 participants receiving mRNA-1273 booster dose in the PP 
Immunogenicity Subset with pre-booster negative SARS-CoV-2 in Study P204 and 
289 young adults (18 to 25 years of age) receiving mRNA-1273 100 µg primary series 
in Study P301, there will be a 90% power to demonstrate noninferiority of the immune 
response, as measured by the antibody GM value, in children receiving a booster dose 
compared with that in adults (18 to 25 years of age) receiving mRNA‑1273 primary 
series in Study P301, at a 2‑sided alpha of 0.05, assuming an underlying true GMR 
value of 1.0 and a noninferiority margin of 1.5. The standard deviation of the natural 
log‑transformed GMT levels is assumed to be 1.5. Also, if the true SRRs were assumed 
to be 95% or higher in children receiving mRNA-1273 booster dose in Study P204 and 
adults receiving mRNA-1273 primary series in Study P301, with between-group true 
difference within 4%, there will be a > 90% power to demonstrate noninferiority by 
SRR in children receiving a booster dose compared with adults receiving primary 
series in Study P301, at a 2-sided alpha of 0.05. 
• In Part 3 for the primary series primary immunogenicity analysis, with approximately 
289 participants receiving mRNA-1273 25 µg primary series in the PP 
Immunogenicity Subset in Study P204 and 289 adults (≥ 18 years of age) receiving 
mRNA-1273 100 µg primary series in Study P301, there will be 84% power to 
demonstrate noninferiority of the immune response, as measured by the antibody GM 
value, in children compared with that in adults (≥ 18 years of age) receiving 
mRNA‑1273 in Study P301, at a 2‑sided alpha of 0.025, assuming a true GMR value 
of 1.0 and a noninferiority margin of 1.5. The standard deviation of the natural 
log‑transformed GMT levels is assumed to be 1.5. Also, if the true SRRs were assumed 
to be 95% or higher in children in Study P204 and adults from Study P301, with 
between-group true difference within 4%, there will be a > 90% power to demonstrate 
noninferiority by SRR in children compared with adults in Study P301, at a 2-sided 
alpha of 0.025. 
• In Part 3 for the third dose primary immunogenicity analysis, with approximately 
289 participants receiving a third dose of mRNA-1273 dose in the PP Immunogenicity 
Subset with pre-third dose negative SARS-CoV-2 in Study P204 and 289 adults (≥ 18 
years of age) receiving mRNA-1273 100 µg primary series in Study P301, there will be 
a 84% power to demonstrate noninferiority of the immune response, as measured by 
the antibody GM value, in children receiving a third dose compared with that in adults 
(≥ 18 years of age) receiving mRNA‑1273 primary series in Study P301, at a 2‑sided 
alpha of 0.025, assuming an underlying true GMR value of 1.0 and a noninferiority 

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margin of 1.5. The standard deviation of the natural log‑transformed GMT levels is 
assumed to be 1.5. Also, if the true SRRs were assumed to be 95% or higher in 
children receiving a third dose of mRNA-1273 dose in Study P204 and adults receiving 
mRNA-1273 primary series in Study P301, with between-group true difference within 
4%, there will be a > 90% power to demonstrate noninferiority by SRR in children 
receiving a third dose compared with adults receiving primary series in Study P301, at 
a 2-sided alpha of 0.025. 
Analysis Sets: 
The analysis sets are defined in the following table: 
Analysis Set 
Description 
Randomization Set 
Part 2: All participants who are randomly assigned, regardless of 
the participants’ treatment status in the study. 
Full Analysis Set (FAS) 
Part 1: All enrolled participants in Part 1 who receive at least 1 
injection of IP. 
Part 2: All randomly assigned participants who receive at least 
1 injection of IP. 
Part 3: All enrolled participants in Part 3 who receive at least 1 
injection of IP. 
Per Protocol (PP) Set 
All participants in the FAS who receive planned doses of IP per 
schedule, comply with the immunogenicity schedule, and have no 
major protocol deviations that impact key or critical data. 
Participants who are RT-PCR positive or seropositive at baseline 
will be excluded from the PP Set. The PP Set in Part 1 will be used 
for all analyses of immunogenicity in Part 1 unless specified 
otherwise. 
Immunogenicity Subset 
A subset of participants in the FAS will be selected for 
immunogenicity sampling and testing. 
Per Protocol Immunogenicity 
Subset 
A subset of participants in the FAS will be selected for 
immunogenicity testing. The PP Immunogenicity Subset includes 
participants selected for the Immunogenicity Subset who receive 
planned doses of IP per schedule, comply with immunogenicity 
testing schedule, and have no major protocol deviations that impact 
key or critical data. Participants who are RT-PCR positive or 
seropositive at baseline will be excluded from the PP 
Immunogenicity Subset, in addition to participants with HIV who 
are receiving highly active anti-retroviral therapy (HAART). The 
PP Immunogenicity Subset will be used for all analyses of 
immunogenicity unless specified otherwise. 

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Safety Set 
All enrolled participants (in Part 1 and Part 3) and all randomly 
assigned participants (in Part 2) who receive at least 1 dose of IP. 
The Safety Set will be used for all analyses of safety except for 
solicited ARs. 
Safety Set for the booster/third dose phase will include all 
participants who receive a booster dose or third dose. 
Solicited Safety Set 
The Solicited Safety Set consists of participants in the Safety Set 
who contributed any solicited AR data. 
The Solicited Safety Set will be used for the analyses of solicited 
ARs. 
Modified Intent-to-Treat 
(mITT) Set 
All participants in the FAS who have no serologic or virologic 
evidence of prior SARS-CoV-2 infection before the first dose of IP 
(both negative RT-PCR test for SARS-CoV-2 and negative 
serology test based on bAb specific to SARS-CoV-2 nucleocapsid) 
at baseline. 
Modified Intent-to-Treat-1 
(mITT1) Set 
All participants in the mITT Set excluding those who received the 
wrong treatment (ie, at least 1 dose received that is not as 
randomized or planned). 
Per Protocol Immunogenicity 
Subset for booster dose or 
third dose phase  
The PP Immunogenicity Subset for booster dose or third dose 
phase includes participants who received planned booster dose or 
third dose per schedule, complied with immunogenicity testing 
schedule, and have no major protocol deviations that impact key or 
critical data, with pre-booster or pre-third dose negative or positive 
SARS-CoV-2. The PP Immunogenicity Subset with pre-booster or 
pre-third dose negative SARS-CoV-2 will be used for the primary 
immunogenicity analysis. 
Abbreviations: AR = adverse reaction; bAb = binding antibody; FAS = full analysis set; HAART = highly active 
anti-retroviral therapy; HIV = human immunodeficiency virus; IP = investigational product; mITT = modified 
intent-to-treat; mITT1 = modified intent-to-treat-1; PP = per protocol; RT-PCR = reverse transcriptase 
polymerase chain reaction; SARS-CoV-2 = severe acute respiratory syndrome coronavirus 2. 
Safety Analyses: 
All safety analyses will be based on the Safety Set, except summaries of solicited ARs, which 
will be based on the Solicited Safety Set. All safety analyses will be provided by vaccination 
group (dose levels of mRNA-1273 and placebo) and by age group. Participants in Part 1 and 
Part 2 of the study and in different age groups who receive the same mRNA-1273 dose level 
may be combined for safety analysis. 
Safety and reactogenicity will be assessed by clinical review of all relevant parameters 
including solicited ARs (local and systemic events), unsolicited AEs, SAEs, MAAEs, AESIs, 
AEs leading to discontinuation, and physical examination findings. 
The number and percentage of participants with any solicited local AR, with any solicited 
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by toxicity grade will be provided. A 2-sided 95% exact CI using the Clopper-Pearson method 
will also be provided for the percentage of participants with any solicited AR. 
The number and percentage of participants with unsolicited AEs, SAEs, MAAEs, severe AEs, 
and AEs leading to discontinuation from IP or withdrawal from the study will be summarized. 
Unsolicited AEs will be presented by the Medical Dictionary for Regulatory Activities 
(MedDRA) preferred term and system organ class. 
The number of events of solicited ARs, unsolicited AEs/SAEs, and MAAEs will be reported 
in summary tables accordingly. 
Solicited AR events (starting within 7 days after any injection) that are serious or lasting 
beyond Day 7 after any injection will also be reported as unsolicited AEs. 
For all other safety parameters, descriptive summary statistics will be provided Further details 
will be described in the SAP. 
Immunogenicity Analyses: 
The primary analysis population for immunogenicity will be the PP Immunogenicity Subset, 
unless specified otherwise. The primary objective of this study is to use the immunogenicity 
response to infer efficacy in participants aged 6 months to < 12 years at the dose level selected 
for expansion. For this objective, analyses of immunogenicity will be performed for each 
pediatric age group separately at the selected dose level based on the participants in the PP 
Immunogenicity Subset. For each pediatric age group, participants in the applicable study part 
in the PP Immunogenicity Subset may be used for immunogenicity primary analysis. 
Participants from Part 1 and Part 2 who receive the same mRNA-1273 dose level selected for 
expansion may be combined for immunogenicity analyses. If the same dose level is selected 
for expansion for more than one age group, these age groups may be combined for 
immunogenicity analyses. 
An accepted antibody threshold of protection against COVID-19 may be available based on 
data from other mRNA-1273 studies or external data. If such a threshold of protection against 
COVID-19 is available, the number and percentage of participants with antibody greater than 
or equal to the threshold at Day 57 will be provided with a 2-sided 95% CI using the 
Clopper-Pearson method. For an age group, if the lower bound of the 95% CI on the 
mRNA-1273 group is > 70%, the primary immunogenicity endpoint of this study will be 
considered to be met for that age group. 
The number and percentage of participants with serum antibody greater than or equal to the 
threshold with 2-sided 95% CI will be provided at each postbaseline time point. The CI will be 
calculated using the Clopper-Pearson method. 

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If an accepted serum antibody threshold of protection against COVID-19 is not established, 
immune response as measured by GM value and SRR in each age group based on Day 57 
antibody levels will be compared with that in young adults (18 to 25 years of age) using data 
from Study P301. An analysis of covariance model will be carried out with antibody at Day 57 
as dependent variable and a group variable (a pediatric age group in Study P204 versus young 
adults [18 to 25 years of age] in Study P301) as the fixed variable for each pediatric age group. 
The GM values of the pediatric age group at Day 57 will be estimated by the geometric least 
square mean (GLSM) from the model. The GMR (ratio of GM values) will be estimated by the 
ratio of GLSM from the model. The corresponding 2-sided 95% CI will be provided to assess 
the difference in immune response between the pediatric age group (Study P204) compared 
with the young adults (18 to 25 years of age) in Study P301 at Day 57. For each pediatric age 
group, the noninferiority of GM value will be considered demonstrated if: 
- 
The lower bound of the 95% CI of the GMR is ≥ 0.67 based on the noninferiority 
margin of 1.5, AND 
- 
The GMR point estimate > 0.8 (minimum threshold). 
For Part 1 or Part 2 booster dose primary immunogenicity analysis of GM in children 
receiving mRNA-1273 booster dose, an analysis of covariance model will be performed to 
assess the difference in the immune response (Ab level) between BD-Day 29 in children 
receiving mRNA-1273 booster dose in Study P204 and Day 57 in young adults (≥ 18-25 years 
of age) receiving mRNA-1273 primary series in Study P301. In the analysis of covariance 
model, antibody titers at BD-Day 29 in P204 children and titers at Day 57 in P301 young 
adults will be a dependent variable, and a group variable (children in Study P204 and young 
adults in Study P301) will be the fixed effect. The GMT will be estimated by the GLSM from 
the model, and its corresponding 95% CI will be provided for each group. The GMR (ratio of 
GMTs) for children in Study P204 with respect to young adults in Study P301 will be 
estimated by the ratio of GLSM from the model and the corresponding 95% CIs will be 
provided. The 95% CI for GMR will be used to assess the between-group difference in 
immune response at BD-Day 29 in children in Study P204 compared with Day 57 following 
the primary vaccine series in young adults in Study P301. The noninferiority of post-booster 
GM in children will be considered demonstrated if the lower bound of the 95% CI of the GMR 
is ≥ 0.67 based on the noninferiority margin of 1.5. 
For Part 3 primary series primary immunogenicity analysis of GM in children 6 years to 
< 12 years of age receiving mRNA-1273 25 µg, which is half of the 50 µg dose level used in 
Part 2 for the same age group, the noninferiority hypothesis testing of GM in children 
compared with adults ≥ 18 years of age from Study P301 will be performed using an analysis 
of covariance model as described above. The noninferiority of GM in children in Part 3 will be 

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considered demonstrated if the lower bound of the (1-alpha) CI of the GMR is ≥ 0.67 based on 
the noninferiority margin of 1.5, where the 1-alpha can be 97.5% or 95% depending on the 
alpha level of 0.025 or 0.05 used for the hypothesis testing. A sensitivity analysis may be 
conducted by using different age group(s) (eg, 18 to 25 years, ≥ 65 years) from Study P301 as 
a comparator. 
For Part 3 third dose primary immunogenicity analysis of GM in children receiving a third 
mRNA-1273 dose, an analysis of covariance model will be performed to assess the difference 
in the immune response at BD-Day 29 between children receiving mRNA-1273 third dose in 
Study P204 and Day 57 in adults (≥18 years of age) receiving mRNA-1273 primary series in 
Study P301. In the analysis of covariance model, antibody titers at BD-Day 29 in P204 
children and titers at Day 57 in P301 young adults will be a dependent variable, and a group 
variable (children in Study P204 and adults in Study P301) will be the fixed effect. The GMT 
will be estimated by the GLSM from the model, and its corresponding 95% CI will be 
provided for each group. The GMR for children in Study P204 with respect to adults in Study 
P301 will be estimated by the ratio of GLSM from the model and the corresponding 95% CIs 
will be provided. The 95% CI for GMR will be used to assess the between-group difference in 
immune response at BD-Day 29 in children in Study P204 compared with Day 57 after the 
primary vaccination series in adults in Study P301. The noninferiority of post-third dose GM 
in children will be considered demonstrated if the lower bound of the (1-alpha) CI of the GMR 
is ≥ 0.67 based on the noninferiority margin of 1.5. 
The number and percentage of participants with seroresponse due to vaccination will be 
provided with 2-sided 95% CI using the Clopper-Pearson method at each postbaseline time 
point with Day 57 being of the primary interest in the analyses for the mRNA-1273 primary 
series in Part 1 or Part 2. The SRR difference with 95% CI (using Miettinen-Nurminen score 
method) at Day 57 will be provided between children receiving mRNA-1273 primary series in 
Study P204 Part 1 or Part 2 and young adults of 18 to 25 years of age receiving mRNA-1273 
primary series in Study P301. For each pediatric age group in Part 1 or Part 2, the 
noninferiority of SRR will be considered demonstrated if: 
- 
The lower bound of the 95% CI of the SRR difference is ≥ -10% based on the 
noninferiority margin of 10%, AND 
- 
The SRR difference point estimate ≥ -5% (minimum threshold). 
For Part 1 or Part 2 booster dose primary immunogenicity analysis of seroresponse in children 
receiving mRNA-1273 booster dose (as applicable), the SRR with 95% CI (using Clopper-
Pearson method) will be summarized. The SRR difference with 95% CI (using Miettinen-
Nurminen score method) to compare post-booster SRR at BD-Day 29 in children in Study 

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P204 with the primary series SRR at Day 57 (28 days after Dose 2) in adults (18 to 25 years of 
age) in Study P301 will be computed. The SRR is defined as a titer change from baseline (pre-
Dose 1) below the LLOQ to ≥ 4 × LLOQ, or at least a 4-fold rise if baseline is ≥ LLOQ. The 
noninferiority of SRR in children receiving mRNA-1273 booster dose will be considered 
demonstrated if the lower bound of the 95% CI of the SRR difference is ≥ -10% based on the 
noninferiority margin of 10%. 
For Part 3 primary series primary immunogenicity analysis of seroresponse in children 6 to 
< 12 years of age receiving mRNA-1273 25 µg which is half of the 50 µg dose level used in 
Part 2 for the same age group, the noninferiority hypothesis testing of SRR in children 
compared with adults ≥ 18 years of age from Study P301 will be performed using the analysis 
of SRR as described above. The SRR difference with (1-alpha) CI at Day 57 will be provided 
between children receiving mRNA-1273 primary series in Study P204 Part 3 and adults of ≥ 
18 years of age receiving mRNA-1273 primary series in Study P301. The 1-alpha can be 
97.5% or 95% depending on the alpha level of 0.025 or 0.05 used for the hypothesis testing. 
The noninferiority of SRR in children receiving mRNA-1273 25 µg primary series in Part 3 
will be considered demonstrated if the lower bound of the (1-alpha) CI of the SRR difference 
is ≥ -10% based on the noninferiority margin of 10%. A sensitivity analysis may be conducted 
by using different age group(s) (eg, 18 to 25 years, ≥ 65 years) from Study P301 as a 
comparator. 
For Part 3 third dose primary immunogenicity analysis of seroresponse in children receiving a 
third dose of mRNA-1273, the SRR with (1-alpha) CI (using Clopper-Pearson method) will be 
summarized, where the 1-alpha can be 97.5% or 95% depending on the alpha level of 0.025 or 
0.05 used for the hypothesis testing. The SRR difference with (1-alpha)% CI (using Miettinen-
Nurminen score method) to compare post-third dose SRR at BD-Day 29 in children in Study 
P204 with the primary series SRR at Day 57 (28 days after Dose 2) in adults (≥ 18 years of 
age) in Study P301 will be computed. The SRR is defined as a titer change from baseline (pre-
Dose 1) below the LLOQ to ≥ 4 × LLOQ, or at least a 4-fold rise if baseline is ≥ LLOQ. The 
noninferiority of SRR in children receiving a third dose of mRNA-1273 in Part 3 will be 
considered demonstrated if the lower bound of the (1-alpha) CI of the SRR difference is ≥ -
10% based on the noninferiority margin of 10%. 
In addition, the GM value of anti-SARS-CoV-2-specific antibody with corresponding 95% CI 
will be provided at each time point. The 95% CIs will be calculated based on the t-distribution 
of the log-transformed values then back transformed to the original scale. For each age group, 
the geometric mean fold‑rise (GMFR) of specific nAb and bAb with corresponding 95% CI at 
each postbaseline time point over preinjection baseline at Day 1 and an earlier time point if 

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applicable will be provided. Descriptive summary statistics including median, minimum, and 
maximum will also be provided. 
Multiplicity Adjustment Between Age Groups: 
A hierarchical sequential hypothesis testing (fixed-sequence method) will be used to adjust 
multiplicity to preserve the family-wise Type I error rate (alpha = 0.05), starting with the 
oldest age group, followed by the middle age group, and then followed by the youngest age 
group. The primary series immunogenicity coprimary endpoint hypotheses for the oldest age 
group (6 years to < 12 years of age) will be tested first at alpha level of 0.05 in Part 1 
expansion or Part 2. If the testing in the oldest age group is statistically significant (meeting 
the noninferiority success criteria of the coprimary endpoints), the alpha level of 0.05 will be 
passed to the testing of the primary series coprimary endpoint hypotheses in the middle age 
group (2 years to < 6 years of age) in Part 2. If the testing in the middle age group is 
statistically significant at alpha level of 0.05, then the alpha 0.05 is preserved for testing the 
primary series coprimary endpoint hypotheses in the youngest age group (6 months to 
< 2 years of age) in Part 2. 
If the hypothesis testing is statistically significant for all the primary series primary 
immunogenicity endpoints in Part 2, the alpha 0.05 is preserved for the hypothesis testing for 
the booster dose primary immunogenicity endpoint in Part 1 or Part 2, starting in the oldest 
age group (6 years to < 12 years of age), then the middle age group (2 years to < 6 years of 
age), followed by the youngest age group (6 months to < 2 years of age) for booster dose in 
applicable age groups in Part 1 or Part 2. The testing will continue through the sequence only 
until an endpoint is not statistically significant (did not meet specified noninferiority success 
criteria of any primary endpoint) in Part 1 or Part 2, in which case the testing will stop. If the 
hypothesis testing for all the booster dose primary endpoints in Part 1 or Part 2 is statistically 
significant (meeting the noninferiority success criteria of the primary endpoints), the alpha 
level of 0.05 will be passed to the hypothesis testing in Part 3. 
In Part 3, half of the type I error rate 0.05 by alpha-splitting will be initially allocated to the 
hypothesis testing for the primary series immunogenicity coprimary endpoints, which will be 
tested initially at alpha level of 0.025. The second 0.025 will be reserved for Part 3 third dose 
hypothesis testing, and a fallback method will be used if applicable. 
• If the testing of the primary series coprimary endpoints in Part 3 is statistically significant 
at alpha level of 0.025 (meeting the noninferiority success criteria of the coprimary 
endpoints), a total of alpha 0.05 will be preserved for the hypothesis testing of the Part 3 
third dose immunogenicity coprimary endpoints. 

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• If the hypothesis testing of the primary series coprimary endpoints in Part 3 is not 
statistically significant at alpha level of 0.025 (not meeting any of the specific 
noninferiority success criteria of the coprimary endpoints), the remaining alpha level of 
0.025 reserved will be used for the hypothesis testing of the Part 3 third dose 
immunogenicity coprimary endpoints. Further, if the hypothesis testing of the third dose 
coprimary endpoints in Part 3 is statistically significant at alpha level of 0.025, the unused 
alpha 0.025 will be passed back to re-testing of primary series coprimary endpoint 
hypothesis in Part 3 at alpha level of 0.025+0.025=0.05 (a fallback method). 
Efficacy Analyses: 
To evaluate the incidence of COVID-19 after vaccination with mRNA-1273 or placebo, the 
incidence rate will be provided by vaccination group, dose level, and age group, calculated as 
the number of cases divided by the total person-time. Participants in Part 1 and Part 2 of the 
study and in different age groups who receive the same mRNA-1273 dose level (if applicable) 
may be combined in the analysis. 
For serologically confirmed SARS-CoV-2 infection or COVID-19, regardless of 
symptomatology or severity, infection rate will be provided by vaccination group, dose level, 
and age group. The same analysis will be conducted for asymptomatic SARS-CoV-2 infection. 
The secondary efficacy analyses will be performed on the PP Set, with sensitivity analyses in 
FAS, modified Intent-to-Treat (mITT) Set, and modified Intent-to-Treat-1 (mITT1) Set. 
Analyses of the efficacy endpoints in Part 2 will be performed for the randomized blinded 
phase. Additional exploratory analyses will be conducted in the blinded and unblinded phases 
for participants randomized to mRNA-1273 in Part 2, and in the unblinded phase for 
participants who are originally randomized to the placebo arm and cross-over to mRNA-1273 
after use of any COVID-19 vaccine is authorized or licensed for the participant’s age group. 
Study Analyses: 
Interim Analyses: 
Part 1: Interim analyses may be performed after all or a subset of participants (with 
immunogenicity samples collected for D1 and D57) have completed Day 57 within an age 
group in Part 1 (one optional interim analysis for each age group, 3 interim analyses total for 
the 3 age groups in Part 1). Analyses of safety and immunogenicity may be conducted at each 
interim analysis. 
Part 2: An interim analysis of immunogenicity and safety will be performed after all or a 
subset of participants have completed Day 57 (1 month after the second dose) in Part 1 or Part 
2 within an age group. This interim analysis will be considered the primary analysis of 

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immunogenicity for a given age group. Another interim analysis on safety may be performed 
after a different subset or all participants have completed Day 57 in an age group. Additional 
interim analysis of immunogenicity and safety may be performed after all or subset of 
participants who receive booster dose have completed BD-Day 29 after the booster dose in an 
age group. 
Part 3: An interim analysis of immunogenicity and safety will be performed after all or a 
subset of participants have completed Day 57 (1 month after the second dose) in Part 3 within 
an age group. This interim analysis will be considered the primary analysis of immunogenicity 
for the primary series in a given age group. A second interim analysis of immunogenicity and 
safety will be performed after all or a subset of participants have completed Day 177/BD-Day 
29 (1 month after third dose). 
An interim analysis of safety for mRNA-1273.214 booster may be performed after all or 
subset of mRNA-1273.214 recipients have completed 6 months of follow-up after the booster 
dose. 
Final Analysis: 
The final analysis of all endpoints will be performed after participants have completed all 
planned study procedures. Results of this analysis will be presented in a final clinical study 
report (CSR), including individual listings. 
Additional information about all study analyses may be provided in the SAP. 

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TABLE OF CONTENTS 
 
CLINICAL STUDY PROTOCOL ..................................................................................................1 
PROTOCOL APPROVAL – SPONSOR SIGNATORY ................................................................3 
DECLARATION OF INVESTIGATOR .........................................................................................4 
PROTOCOL AMENDMENT SUMMARY OF CHANGES ..........................................................5 
PROTOCOL SYNOPSIS ................................................................................................................9 
TABLE OF CONTENTS ...............................................................................................................43 
LIST OF TABLES .........................................................................................................................47 
LIST OF FIGURES .......................................................................................................................48 
LIST OF ABBREVIATIONS AND TERMS ................................................................................49 
1 
INTRODUCTION ......................................................................................................53 
1.1 
Study Rationale ...........................................................................................................53 
1.1.1 
Background and Overview .........................................................................................55 
1.1.2 
Nonclinical Studies .....................................................................................................56 
1.1.3 
Clinical Studies ...........................................................................................................57 
1.2 
Benefit/Risk Assessment ............................................................................................59 
1.2.1 
Potential Benefits From Participation .........................................................................59 
1.2.2 
Risks From Study Participation and Their Mitigation ................................................59 
1.2.3 
Overall Benefit/Risk Conclusion ................................................................................61 
2 
OBJECTIVES AND ENDPOINTS ............................................................................63 
3 
STUDY DESIGN .......................................................................................................67 
3.1 
General Design ...........................................................................................................67 
3.1.1 
Study Periods ..............................................................................................................74 
3.2 
Scientific Rationale for Study Design ........................................................................78 
3.3 
Justification for Dose, Control Product, and Choice of Study Population .................79 
3.4 
End-of-Study Definition .............................................................................................80 
4 
STUDY POPULATION .............................................................................................81 
4.1 
Inclusion Criteria ........................................................................................................81 
4.2 
Exclusion Criteria .......................................................................................................82 
4.3 
Lifestyle Restrictions ..................................................................................................84 
4.4 
Screen Failures ............................................................................................................84 

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5 
STUDY TREATMENT ..............................................................................................85 
5.1 
Investigational Product Administered ........................................................................85 
5.2 
Randomization ............................................................................................................85 
5.3 
Dosing and Management of mRNA-1273 Vaccine ....................................................85 
5.3.1 
Preparation of Study Vaccine for Injection ................................................................85 
5.3.2 
Administration of Study Vaccine ...............................................................................86 
5.3.3 
Study Vaccine Delivery and Receipt ..........................................................................86 
5.3.4 
Study Vaccine Packaging and Labeling .....................................................................87 
5.3.5 
Study Vaccine Storage ................................................................................................87 
5.3.6 
Study Vaccine Accountability ....................................................................................87 
5.3.7 
Study Vaccine Handling and Disposal .......................................................................88 
5.4 
Study Treatment Compliance .....................................................................................88 
5.5 
Prior and Concomitant Medications ...........................................................................88 
5.5.1 
Prior Medications and Therapies ................................................................................88 
5.5.2 
Concomitant Medications and Therapies ...................................................................89 
5.5.3 
Concomitant Medications and Vaccines That May Lead to the Elimination of 
a Participant from Per Protocol Analyses ....................................................................90 
5.6 
Intervention After the End of the Study .....................................................................90 
6 
DELAYING OR DISCONTINUING STUDY TREATMENT AND 
PARTICIPANT WITHDRAWAL FROM THE STUDY ..........................................91 
6.1 
Criteria for Delay of Vaccine Administration ............................................................91 
6.1.1 
Individual Participant Criteria for Delay of Study Vaccination .................................91 
6.2 
Discontinuing Study Vaccination ...............................................................................92 
6.3 
Participant Discontinuation/Withdrawal from the Study ...........................................93 
6.3.1 
End-of-Study Visit (Prior to Day 394 or Day 514/BD-Day 366) ...............................94 
6.4 
Study Pause Rules.......................................................................................................94 
6.5 
Lost to Follow-up .......................................................................................................96 
7 
STUDY ASSESSMENTS AND PROCEDURES ......................................................97 
7.1 
Safety Assessments and Procedures ...........................................................................98 
7.1.1 
Use of Electronic Diaries ............................................................................................98 
7.1.2 
Safety Telephone Calls .............................................................................................101 
7.1.3 
Safety Laboratory Assessments ................................................................................101 
7.1.4 
Physical Examinations ..............................................................................................101 

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7.1.5 
Assessment for SARS-CoV-2 Infection ...................................................................102 
7.2 
Blood Collections for Immunogenicity Assessments and Biomarker Samples .......105 
7.3 
Inferred Efficacy Assessments .................................................................................107 
7.3.1 
Vaccine Effectiveness Assessments .........................................................................107 
7.3.2 
Surveillance for COVID-19 Symptoms ....................................................................109 
7.3.3 
Follow-up/Convalescent Period After Diagnosis with COVID-19 ..........................113 
7.4 
Safety Definitions and Related Procedures ..............................................................113 
7.4.1 
Adverse Event ...........................................................................................................113 
7.4.2 
Serious Adverse Events ............................................................................................114 
7.4.3 
Solicited Adverse Reactions .....................................................................................115 
7.4.4 
Medically Attended Adverse Events ........................................................................119 
7.4.5 
Adverse Events of Special Interest ...........................................................................120 
7.4.6 
Recording and Follow-up of Pregnancy ...................................................................123 
7.4.7 
Eliciting and Documenting Adverse Events .............................................................124 
7.4.8 
Assessment of Intensity ............................................................................................124 
7.4.9 
Assessment of Causality ...........................................................................................125 
7.4.10 
Reporting Adverse Events ........................................................................................125 
7.4.11 
Reporting SAEs ........................................................................................................126 
7.4.12 
Time Period and Frequency for Collecting AE, AESI, and SAE Information .........127 
7.4.13 
Method of Detecting AEs and SAEs ........................................................................128 
7.4.14 
Follow-up of AEs and SAEs .....................................................................................128 
7.4.15 
Regulatory Reporting Requirements for SAEs .........................................................128 
7.5 
Safety Monitoring .....................................................................................................129 
7.5.1 
Internal Safety Team .................................................................................................129 
7.5.2 
Data Safety Monitoring Board ..................................................................................129 
7.6 
Treatment of Overdose .............................................................................................130 
7.7 
Pharmacokinetics ......................................................................................................130 
7.8 
Pharmacodynamics ...................................................................................................130 
7.9 
Biomarkers ................................................................................................................130 
7.10 
Health Economics .....................................................................................................130 
8 
STATISTICAL ANALYSIS PLAN .........................................................................131 
8.1 
Blinding and Responsibility for Analyses ................................................................131 
8.1.1 
Breaking the Blind ....................................................................................................132 

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8.2 
Statistical Hypothesis ................................................................................................133 
8.3 
Power and Sample Size ............................................................................................138 
8.4 
Analysis Sets .............................................................................................................140 
8.5 
Statistical Methods ....................................................................................................142 
8.5.1 
Baseline Characteristics and Demographics .............................................................142 
8.5.2 
Safety Analyses ........................................................................................................142 
8.5.3 
Immunogenicity Analyses ........................................................................................143 
8.5.4 
Efficacy Analysis ......................................................................................................148 
8.5.5 
Exploratory Analyses ................................................................................................148 
8.5.6 
Subgroup Analyses ...................................................................................................149 
8.6 
Study Analyses .........................................................................................................149 
8.6.1 
Interim Analyses .......................................................................................................149 
8.6.2 
Final Analysis ...........................................................................................................149 
9 
REFERENCES .........................................................................................................150 
10 
SUPPORTING DOCUMENTATION AND OPERATIONAL 
CONSIDERATIONS ................................................................................................157 
10.1 
APPENDIX 1: Schedule of Assessments .................................................................157 
10.2 
APPENDIX 2: Study Governance Considerations ...................................................176 
10.2.1 
Regulatory and Ethical Considerations ....................................................................176 
10.2.2 
Study Monitoring ......................................................................................................176 
10.2.3 
Audits and Inspections ..............................................................................................177 
10.2.4 
Financial Disclosure .................................................................................................178 
10.2.5 
Recruitment Procedures ............................................................................................178 
10.2.6 
Informed Consent/Assent Process ............................................................................178 
10.2.7 
Protocol Amendments ..............................................................................................179 
10.2.8 
Protocol Deviations ..................................................................................................180 
10.2.9 
Data Protection .........................................................................................................180 
10.2.10 
Sample Retention and Future Biomedical Research ................................................181 
10.2.11 
Dissemination of Clinical Study Data ......................................................................182 
10.2.12 
Data Quality Assurance and Quality Control ...........................................................182 
10.2.13 
Data Collection and Management ............................................................................183 
10.2.14 
Source Documents ....................................................................................................184 
10.2.15 
Retention of Records ................................................................................................184 

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10.2.16 
Study and Site Closure..............................................................................................184 
10.2.17 
Publication Policy .....................................................................................................185 
10.2.18 
Body Mass Index Charts for Boys and Girls ............................................................186 
10.3 
APPENDIX 3: Contraceptive Guidance ...................................................................192 
10.4 
APPENDIX 4: Adverse Event of Special Interest Terms ........................................193 
10.5 
APPENDIX 5: Protocol Amendment History ..........................................................196 
10.5.1 
Amendment 8, 23 May 2022 ....................................................................................196 
10.5.2 
Amendment 7, 18 Feb 2022 ......................................................................................198 
10.5.3 
Amendment 6, 07 Jan 2022 ......................................................................................201 
10.5.4 
Amendment 5, 29 Sep 221 ........................................................................................203 
10.5.5 
Amendment 4, 25 Aug 2021 .....................................................................................206 
10.5.6 
Amendment 3, 23 Jul 2021 .......................................................................................208 
10.5.7 
Amendment 2, 17 Jun 2021 ......................................................................................209 
10.5.8 
Amendment 1, 30 Apr 2021 .....................................................................................212 
 
LIST OF TABLES 
Table 1: 
Age Groups and mRNA-1273 Primary Series Dose Levels .......................................61 
Table 2: 
Study Objectives and Endpoints .................................................................................63 
Table 3: 
Planned Age Groups and mRNA-1273 Dose Levels in Part 1, Part 2, and 
Part 3 of the Study ......................................................................................................68 
Table 4: 
Optional Booster Doses for Part 1 and Part 2 Participants .........................................69 
Table 5: 
Pause Rule Criteria, Events, and Thresholds ..............................................................95 
Table 6: 
Age-Specific Cut-Offs for Vital Signs and Laboratory Variables ............................108 
Table 7: 
Definition of Renal-, Liver- and Neurological Dysfunction for Pediatric 
Population (< 12 years of age) ..................................................................................109 
Table 8: 
Solicited Adverse Reactions and Grades: Age 37 Months to < 12 years1 ................116 
Table 9: 
Solicited Adverse Reactions and Grades: Age 6 Months to ≤ 36 Months1 ..............117 
Table 10: Analysis Sets .............................................................................................................141 
Table 11: Analysis Strategy for Safety Parameters ..................................................................143 
Table 12: Schedule of Assessments for Parts 1 and 2, Study Arms 1 Through 13 ..................158 

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Table 13: Schedule of Assessments for Placebo Recipient Cross-Over Vaccination 
with mRNA-1273 if any COVID-19 Vaccine is Authorized or Licensed for 
Participant’s Age Group1 ..........................................................................................162 
Table 14: Phlebotomy Schedule for Serology, Biomarker Sample, and Cell-Mediated 
Immunity for Part 2 (Expansion) of the Study .........................................................164 
Table 15: Schedule of Assessments for Optional Booster Doses with mRNA-1273 for 
Parts 1 and 2, Study Arms 1 Through 9 under Protocol Amendment 7 ...................165 
Table 16: Phlebotomy Schedule for Participants Opting for Booster Dose with mRNA-
1273 under Amendment 7 by Part and Age Group ..................................................168 
Table 17: Schedule of Assessments for Part 3, Study Arm 14 .................................................169 
Table 18: Phlebotomy Schedule for Serology for Part 3 ..........................................................173 
Table 19: Schedule of Assessments for Optional Booster Doses with mRNA-1273.214 
for Previously Unboosted Participants from Part 1 and Part 2 under Protocol 
Amendment 9 ............................................................................................................173 
 
LIST OF FIGURES 
Figure 1: 
Study Schema .............................................................................................................69 
Figure 2: 
Surveillance for COVID-19 Symptoms and the Corresponding Clinical Data 
Pathways ...................................................................................................................111 
 
 

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LIST OF ABBREVIATIONS AND TERMS 
The following abbreviations and terms are used in this study protocol. 
Abbreviation or Specialist Term 
Definition 
AE 
adverse event 
AESI 
adverse event of special interest 
AR 
adverse reaction 
bAb 
binding antibody 
BD 
booster dose 
BLA 
Biologics License Application 
BMI 
body mass index 
CD 
cluster of differentiation 
CDC 
US Centers for Disease Control and Prevention 
CEAC 
Cardiac Event Adjudication Committee 
CFR 
Code of Federal Regulations 
CI 
confidence interval 
CLIA 
Clinical Laboratory Improvement Amendments 
CMI 
cell-mediated immunity 
CoV 
coronavirus 
COVID-19 
coronavirus disease 2019 
CRO 
contract research organization 
CSR 
clinical study report 
DMID 
Division of Microbiology and Infectious Diseases 
DSMB 
Data Safety Monitoring Board 
DSPC 
1,2-distearoyl-sn-glycero-3-phosphocholine 
eCRF 
electronic case report form 
ECG 
electrocardiogram 
EDC 
electronic data capture 
eDiary 
electronic diary 
ERD 
enhanced respiratory disease 

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Abbreviation or Specialist Term 
Definition 
EUA 
Emergency Use Authorization 
FAS 
Full Analysis Set 
FDA 
Food and Drug Administration 
GCP 
Good Clinical Practice 
GLSM 
geometric least squares mean 
GM 
geometric mean 
GMFR 
geometric mean fold-rise 
GMR 
geometric mean ratio 
GMT 
geometric mean titer 
HAART 
highly active anti-retroviral therapy 
HCP 
healthcare practitioner 
HIV 
human immunodeficiency virus 
IB 
investigator’s brochure 
ICF 
informed consent form 
ICH 
International Council for Harmonisation 
ICU 
intensive care unit 
IgG 
immunoglobulin G 
IM 
intramuscular(ly) 
IND 
investigational new drug 
IP 
investigational product 
IRB 
institutional review board 
IST 
internal safety team 
LAR 
legally authorized representative 
LLOQ 
lower limit of quantification 
LNP 
lipid nanoparticle 
LTFU 
lost to follow-up 
MAAE 
medically attended adverse event 
MedDRA 
Medical Dictionary for Regulatory Activities 

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Abbreviation or Specialist Term 
Definition 
MERS 
Middle East respiratory syndrome 
MIS-C 
multisystem inflammatory syndrome in children 
mITT 
modified Intent-to-Treat 
mITT1 
modified Intent-to-Treat-1 
mRNA 
messenger RNA 
nAb 
neutralizing antibody(ies) 
NHP 
nonhuman primate 
NIAID 
National Institute of Allergy and Infectious Diseases 
PEG 
polyethylene glycol 
PEG2000-DMG 
1-monomethoxypolyethyleneglycol-2,3-dimyristylglycerol 
polyethylene glycol 2000 
PI 
Principal investigator 
PP 
per protocol 
PsVNA 
Pseudovirus neutralizing antibody 
QA 
quality assurance 
RT-PCR 
reverse transcriptase polymerase chain reaction 
S 
spike 
S2P 
S protein stabilized with 2 proline mutations 
SAE 
serious adverse event 
SAP 
statistical analysis plan 
SARS 
severe acute respiratory syndrome 
SARS-CoV-2 
severe acute respiratory syndrome coronavirus 2 
SM-102 
heptadecan-9-yl 8-((2-hydroxyethyl)(6-oxo-6-
(undecyloxy)hexyl)amino)octanoate 
SoA 
schedule of assessments 
SRR 
seroresponse rate 
Study P301 
Study mRNA-1273-P301; NCT04470427 
Th 
T helper cell 

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Abbreviation or Specialist Term 
Definition 
VE 
vaccine efficacy 
VTEU 
Vaccine and Treatment Evaluation Units 
WHO 
World Health Organization 
WOCBP 
woman of childbearing potential 

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1 INTRODUCTION 
1.1 Study Rationale 
Coronaviruses (CoVs) are a large family of viruses that cause illness ranging from the common 
cold to more severe diseases, such as Middle East respiratory syndrome (MERS) and severe 
acute respiratory syndrome (SARS). Coronaviruses are zoonotic, meaning that they are 
transmitted between animals and people. An outbreak of the coronavirus disease 2019 (COVID-
19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) began in Wuhan, 
Hubei Province, China in December 2019 and has spread throughout China and to over 215 other 
countries, territories, and areas, including the United States (WHO 2020a). On 11 Mar 2020, the 
World Health Organization (WHO) officially declared COVID-19 a pandemic. As of 
30 Jan 2021, the WHO dashboard (WHO 2020b) reported that there have been more than 2.1 
million COVID-19 deaths worldwide. As of 29 Jan 2021, the US Centers for Disease Control 
and Prevention (CDC) reported over 25 million cases of COVID-19 in all 50 states and 5 
jurisdictions, with 431,619 attributed and probable deaths (CDC 2020a). While the CDC reports 
that the highest risk of disease burden is in older adults and populations with certain underlying 
comorbid conditions such as heart disease, diabetes, and lung disease, a substantial burden in 
children is now being recognized. Evidence is emerging (described below) to suggest that 
children < 18 years of age, particularly adolescents, may be disproportionately contributing to 
the number of new cases as schools re-open at varying degrees of in-person learning. As of 
29 Jan 2021, the CDC reported 2,125,186 cases of COVID-19 in children less than 18 years of 
age (11.1% of all US cases) and 267 deaths (approximately 0.1% of all US deaths; CDC 2020b). 
During incubation, those infected can also transmit the virus before developing symptoms 
(Chen et al 2020). Person-to-person transmission occurs primarily via direct contact or through 
droplets spread by coughing or sneezing from an infected individual, whether symptomatic or 
not (Chen et al 2020; Licciardi et al 2020; Rothan and Byrareddy 2020; Shen et al 2020). 
SARS-CoV-2 can also be transmitted via the fecal-oral pathway (Cruz and Zeichner 2020). 
During the COVID-19 pandemic, children throughout much of the world have had school 
attendance limited in an attempt to control infection. Therefore, the main source of infection for 
SARS-CoV-2 in children, with or without clinical symptoms, is infected household contacts. 
Indeed, a retrospective cohort study of high school students, parents and siblings of students, 
teachers, and staff conducted in France in early April 2020 suggests that there was little to no 
transmission from infected students to other students or school staff. Rather, a high prevalence of 
antibodies against SARS-CoV-2 among families suggests familial clustering of COVID-19 cases 
(Fontanet et al 2020). 

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A recent report of COVID-19 trends in school-aged children in the United States from 
01 Mar 2020 to 19 Sep 2020 indicates that 37% of laboratory-confirmed cases of COVID-19 in 
school-aged children occurred in children 5 to 11 years of age while 63% occurred in adolescents 
12 to 17 years of age (Leeb et al 2020). The weekly incidence among adolescents was 37.4 cases 
per 100,000 compared with 19.0 cases per 100,000 for younger children. Among school-aged 
children with laboratory-confirmed COVID-19, 58% reported at least one symptom and 5% 
reported no symptoms, although information on symptoms was missing or unknown for 37%. 
Overall, 1.2% of school-aged children with COVID-19 were hospitalized, 0.1% required 
intensive care unit (ICU) admission, and < 0.01% died of COVID-19. Furthermore, at least one 
underlying condition was reported in 3% of adolescents and 2% of younger children. Chronic 
lung disease, including asthma, was most commonly reported (55%), followed by disability 
(neurologic or neurodevelopmental disorders, intellectual or physical disability, and vision or 
hearing impairment; 9%), immunosuppressive conditions (7%), diabetes (6%), psychological 
conditions (6%), cardiovascular disease (5%), and severe obesity (4%) (Leeb et al 2020). Based 
on the COVID-NET report, in 42.3% of children with at least 1 underlying condition, the most 
prevalent conditions were obesity (37.8%), chronic lung disease (18.0%), and prematurity 
(15.4%) (Kim et al 2020). Of particular interest is the phenomenon known as multisystem 
inflammatory syndrome in children (MIS-C) (PICS 2020). Since those early reports, a number of 
articles have been published describing a hyperinflammatory syndrome with features of 
Kawasaki disease in children and adolescents infected with SARS-CoV-2 (Belhadjer et al 2020; 
Dufort et al 2020; Verdoni et al 2020). Targeted surveillance in the United States from March 
through May 2020 revealed 186 patients across 26 states who met a pre-specified case definition 
of MIS-C (Feldstein et al 2020). The median age was 8.3 years (interquartile range: 3.3 to 12.5 
years). Most (73%) were previously healthy, and 70% were positive for SARS-CoV-2 by reverse 
transcriptase polymerase chain reaction (RT-PCR) or antibody testing. The condition affected a 
variety of organ systems, most commonly the gastrointestinal, cardiovascular, hematologic, 
mucocutaneous, and respiratory systems. More recently, the Brighton Collaboration has drafted a 
manuscript proposing case definitions of MIS-C based on 5 levels of diagnostic certainty (Vogel 
et al 2020). 
Evidence suggests that there is substantial burden of COVID-19 in younger age groups. Another 
study examined the age distribution of COVID-19 in the United States from May to August 2020 
based on 3 indicators: COVID-19-like illness-related emergency department visits, positive 
RT-PCR results for SARS-CoV-2, and confirmed COVID-19 cases (Boehmer et al 2020). These 
authors report an estimated mean COVID-19 incidence during this time period of 179.3 cases per 
100,000 in individuals 10 to 19 years of age. Finally, a recent report describes an adolescent 
(13 year old female), whose only symptom was nasal congestion, yet she was the index case in 
an outbreak of COVID-19 linked to a family gathering that ultimately crossed 4 states and 

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included 5 households and 11 individuals (Schwartz et al 2020). A June COVID-19 outbreak in a 
Georgia overnight camp demonstrated that children 6 to 19 years of age are susceptible to 
SARS-CoV-2 infection and transmission (Szablewski et al 2020). In addition, in the second half 
of July, Rhode Island childcare programs reported 52 confirmed and probable childcare-
associated COVID-19 cases, 30 (58%) cases of which were among children with a median age of 
5 years (Link-Gelles et al 2020). This suggests that adolescents and children can serve as the 
source of COVID-19 outbreaks, even when their symptoms are mild, as in these cases. 
There is currently no approved vaccine against SARS-CoV-2 for children. In December 2020, 
following review of safety and efficacy data observed to date, the Food and Drug Administration 
(FDA) granted Emergency Use Authorization (EUA) to 2 messenger RNA (mRNA)-based 
SARS-CoV-2 vaccines, including mRNA-1273, for adults. In January 2022, the FDA has 
approved the Biologics License Application (BLA) for SPIKEVAX (mRNA-1273) to prevent 
COVID-19 in individuals 18 years of age and older. In October 2021, the FDA granted EUA to 
an mRNA-based SARS-CoV-2 vaccine in children aged 5 to 11 years old. To address prevention 
of pediatric COVID-19 as well as to potentially help curb SARS-CoV-2 transmission, there is an 
urgent public health need for rapid development of SARS-CoV-2 vaccines in children. 
The objective for this Phase 2/3 study is to evaluate the safety, tolerability, reactogenicity, and 
effectiveness of up to 3 dose levels (25, 50, and 100 µg) of mRNA-1273 vaccine administered as 
2 doses 28 days apart (and an optional booster dose at 10 or 25 µg) (Section 3.1) to healthy 
children 6 months to < 12 years of age divided into 3 age groups (6 years to < 12 years, 2 years 
to < 6 years, and 6 months to < 2 years), as well as a lower dose three-dose series of 25 µg in 
children 6 years to < 12 years old. Another Phase 2/3 study to evaluate the safety and 
reactogenicity of a single dose level (100 µg) of mRNA-1273 vaccine administered as 2 doses 
28 days apart to an adolescent population (12 to < 18 years of age) as well as a booster dose is 
ongoing. 
1.1.1 Background and Overview 
The Sponsor has developed a rapid-response proprietary vaccine platform based on a mRNA 
delivery system. The platform is based on the principle and observations that cells in vivo can 
take up mRNA, translate it, and then present viral antigen(s) on the cell surface. The delivered 
mRNA does not enter the cellular nucleus or interact with the genome, is nonreplicating, and is 
expressed transiently. Messenger RNA vaccines have been used to induce immune responses 
against infectious pathogens such as cytomegalovirus (NCT03382405), human metapneumovirus 
and parainfluenza virus type 3 (NCT03392389), and influenza virus (NCT03076385 and 
NCT03345043). 

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The Sponsor is using its mRNA-based platform to develop a novel lipid nanoparticle 
(LNP)-encapsulated mRNA-based vaccine against SARS-CoV-2 (mRNA-1273). mRNA-1273 
encodes for the full-length spike (S) protein of SARS-CoV-2, modified to introduce 2 proline 
residues to stabilize the S protein (S2P). It has been confirmed that the stabilized SARS-CoV-2 
S2P expresses well and is in the prefusion conformation (Wrapp et al 2020). The CoV S protein 
mediates attachment and entry of the virus into host cells (by fusion), making it a primary target 
for neutralizing antibodies (nAb) that prevent infection (Corti et al 2015; Wang et al 2015; 
Yu et al 2015; Johnson et al 2016; Chen et al 2017; Wang et al 2018; Kim et al 2019; 
Widjaja et al 2019; Corbett et al 2020a; Ju et al 2020; Robbiani et al 2020). 
1.1.2 Nonclinical Studies 
The National Institute of Allergy and Infectious Diseases (NIAID) Vaccine Research Center and 
the Sponsor performed nonclinical studies in young and aged wild-type mice, Syrian Golden 
hamsters, and rhesus macaques (nonhuman primates [NHPs]) to evaluate dose-ranging responses 
to mRNA-1273 (immunogenicity) and high-dose virus SARS-CoV-2 challenge (protection) and 
to address the theoretical concern of enhanced respiratory disease (ERD) mediated by 
vaccine-induced antibody responses and/or T helper cell (Th) 2-directed T-cell responses 
observed with other vaccines against viral respiratory diseases (Graham 2020). 
Nonclinical animal studies demonstrated that mRNA-1273 is immunogenic in all species 
assessed, with a dose-dependent response in immunoglobulin G (IgG) binding antibody (bAb) 
titers and a correlation that is statistically significant between bAb and nAb activity. In addition, 
antigen-specific T-cell responses were observed in studies in mice and NHPs. The Th1-directed 
cluster of differentiation (CD) 4 and CD8 T-cell responses were measured after boost in animals 
that were vaccinated with mRNA-1273. In various animal models, immunological measurements 
suggested that Th1 responses predominated, IgG2a/c/IgG1 ratios were favorable, and high levels 
of SARS-CoV-2 nAb were observed, suggesting that ERD after mRNA-1273 administration 
would be unlikely. In addition to measuring the immune response, mice, hamsters, and NHPs 
were challenged with high-dose SARS-CoV-2 virus. In these studies, dose levels were included 
that were predicted to be optimal (fully protective) and suboptimal (subprotective). At higher 
doses, mice and NHPs were fully protected from viral replication in both lungs and nasal 
passages. At subprotective dose levels, animals either remained fully protected or had reduced 
viral lung burden post challenge versus control animals (Corbett et al 2020a; Corbett et al 
2020b). 
Overall, nonclinical animal studies demonstrated that mRNA-1273 is safe and well tolerated, is 
immunogenic, fully protects animals from challenge at optimal dose levels, and does not result in 
ERD at protective or subprotective dose levels. 

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In support of the development of mRNA-1273 for prophylaxis against SARS-CoV-2 infection, 
nonclinical immunogenicity, biodistribution, and safety studies have been completed with similar 
mRNA-based vaccines formulated in LNPs containing 57heptadecane-9-yl 
8-((2-hydroxyethyl)(6-oxo-6-(undecyloxy)hexyl)amino)octanoate (SM-102), the novel 
proprietary lipid used in the mRNA-1273 LNP formulation. 
A detailed review of nonclinical experience with mRNA-1273 vaccine is provided in the 
investigator’s brochure (IB). 
1.1.3 Clinical Studies 
The mRNA-1273 vaccine is currently being evaluated in 4 ongoing trials. 
The first is a safety and immunogenicity Phase 1 study (NCT04283461) sponsored and 
conducted by the Division of Microbiology and Infectious Diseases (DMID; investigational new 
drug [IND] application 019635) of the NIAID. The Phase 1 study is an open-label dose-ranging 
study of mRNA-1273 in healthy adult male and nonpregnant female participants in 3 age groups: 
18 to 55 years, inclusive (60 participants); 56 to 70 years, inclusive (30 participants); and 
≥ 71 years (30 participants). Participants were randomly assigned to 1 of 4 dose levels of 
mRNA-1273: 25 μg, 50 μg, 100 μg, and 250 μg. Each participant received the same dose by 
intramuscular (IM) injection (0.5 mL) of mRNA-1273 on Days 1 and 29 in the deltoid muscle. 
Blood samples were obtained at baseline, Days 8, 15, 29 (prior to Dose 2), 36, 43, and 57, as 
well as 3, 6, and 12 months after the second vaccination (Days 119, 209, and 394, respectively). 
Safety monitoring is ongoing for 12 months after the second injection. 
On 14 Jul 2020, a preliminary report of findings in this Phase 1 study through Day 57 for the 
18- to 55-year age-cohort (25, 100, and 250 µg dosage groups) was published (Jackson et al 
2020). After the second injection, serum viral neutralizing activity was detected by 2 methods in 
all 42 participants evaluated (of 45 enrolled), with values that were comparable to or greater than 
the geometric mean titers (GMT) measured in the convalescent serum samples. Regarding safety, 
no serious adverse events (SAEs) were reported and no study-halting rules were triggered. In 
general, solicited systemic adverse reactions (ARs) were more common after the second 
injection. Solicited ARs that occurred in more than half the participants included fatigue, chills, 
headache, myalgia, and pain at the injection site. While none of the participants (N= 45) at any 
dose level experienced fever following the first dose, mild fever was observed in 5 participants 
(33%), moderate fever was observed in 1 participant (6.7%), and no participants experienced 
severe fever at 100 µg following the second dose. Data on 40 older adults > 55 years of age who 
received 2 doses of either 25 or 100 µg in the same Phase 1 DMID study were recently published 
(Anderson et al 2020). After the second injection, serum neutralizing activity was detected in all 
participants by multiple methods with binding and neutralizing antibody titers similar to those 

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reported in adults 18 to 55 years of age and above the median for convalescent serum. Solicited 
ARs were predominantly mild or moderate in severity and most frequently included fatigue, 
chills, headache, myalgia, and pain at the injection site. Specifically, regarding fever, no 
participant reported fever of any severity following the first injection. Following the second 
injection, 2 participants in the 100-µg dose group reported fever categorized as mild. All 
participants have been vaccinated, and safety and immunogenicity follow-up is ongoing. Indeed, 
immunogenicity data through 119 days after the first vaccination for 34 participants revealed 
binding and neutralizing GMTs that exceeded the median GMTs in a panel of convalescent sera 
from 41 controls. No SAEs were noted, no study-halting rules were met, and no new related 
adverse events (AEs) were reported after Day 57 (Widge et al 2021). 
Additionally, an ongoing, placebo-controlled, dose-finding Phase 2a study (mRNA-1273-P201; 
NCT04405076) conducted by the Sponsor under IND 19745 aims to evaluate the safety, 
reactogenicity, and immunogenicity of mRNA-1273 administered as 2 doses 28 days apart at 
dose levels of 50 and 100 µg. The study is being conducted in 600 healthy adults in 2 age 
cohorts: 18 to 54 years of age (300 participants) and at least 55 years of age (300 participants). 
All participants were randomly assigned in a ratio of 1:1:1 to receive either placebo or mRNA-
1273 at 1 of 2 doses, either 50 µg or 100 µg. The study was designed to begin with parallel 
enrollment of all 300 participants in Cohort 1 (≥ 18 to < 55 years old) and a sentinel group of 50 
participants in Cohort 2 (≥ 55 years old). An independent safety monitoring committee (SMC) 
reviewed all blinded and unblinded safety data through Day 57 (1 month after Dose 2) for both 
cohorts and found the vaccine tolerable, saw no safety concerns, and recommended continuing 
the study as planned. The study is now completely enrolled, and all dosing is complete; 
participants are undergoing additional serologic testing and safety follow-up. 
The 100 µg dose level is currently being investigated in a large Phase 3 efficacy study 
(mRNA-1273-P301; NCT04470427) in approximately 30,000 adults 18 years of age and older, 
randomly assigned 1:1 to receive either vaccine or placebo. Recently published data showed a 
vaccine efficacy (VE) of 94.1% against symptomatic COVID-19 illness with onset at least 14 
days after the second injection (Baden et al 2021). Although moderate transient reactogenicity 
occurred more frequently in the mRNA-1273 group, SAEs were rare, and the incidence was 
similar between the 2 groups. On 18 Dec 2020, the Moderna COVID-19 vaccine was authorized 
by the US FDA for emergency use in individuals ≥ 18 years of age. The participants in this 
Phase 3 study are currently undergoing assessments for long-term safety and durability of VE. 
Finally, a Phase 2/3, randomized, observer-blind, placebo-controlled study (mRNA-1273-P203) 
conducted by the Sponsor under IND 19745 is evaluating the safety, reactogenicity, and 
effectiveness of mRNA-1273 in healthy adolescents 12 to < 18 years of age. This study began 
enrolling in December 2020 and enrolled 3,740 participants randomly assigned 2:1 to receive 

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mRNA-1273 100 µg or placebo administered as 2 doses 28 days apart. Participants will be 
followed for 12 months after the last dose. 
A detailed review of the clinical experience with LNPs containing SM-102 (mRNA vaccines and 
placebo) is provided in the IB. 
1.2 Benefit/Risk Assessment 
1.2.1 Potential Benefits From Participation 
The following benefits may accrue to participants: 
• The mRNA-1273 vaccine may be an effective vaccine against COVID-19 in the study 
population as well as the rare but serious complication of MIS-C (Zambrano et al 2022). 
• Participants will have a baseline (Day 1) evaluation for SARS-CoV-2 infection and 
ongoing surveillance for COVID-19 throughout the study. 
• The study will contribute to the development of a vaccine against COVID-19 for children 
6 months to < 12 years of age. 
1.2.2 Risks From Study Participation and Their Mitigation 
Immediate systemic allergic reactions (eg, anaphylaxis) can occur following any vaccination. 
These reactions are very rare and are estimated to occur once per 450,000 vaccinations for 
vaccines that do not contain allergens such as gelatin or egg protein (Zent et al 2002). As a 
precaution, all participants will remain under observation at the study site for at least 30 minutes 
after injection. 
Vasovagal syncope (fainting) can occur before or after any vaccination, is usually triggered by 
the pain or anxiety caused by the injection and is not related to the substance injected. Therefore, 
it is important that standard precautions and procedures are followed to avoid injury from 
fainting. 
Intramuscular injection with other mRNA vaccines manufactured by the Sponsor containing the 
SM-102 LNP commonly results in a transient and self-limiting local inflammatory reaction. This 
typically includes pain, erythema (redness), or swelling (hardness) at the injection site, which are 
mostly mild to moderate in severity and usually occur within 24 hours of injection. In the large 
Phase 3 efficacy study of mRNA-1273 described above, delayed injection site reactions occurred 
with an incidence of approximately 1%. These reactions typically began 8 days or more 
following injection, were mostly not severe, and were rarely observed after the second dose. 
The majority of local and systemic solicited ARs observed after injection with mRNA-1273 at 
the 100-µg dose level have been mild to moderate in severity (Section 1.1.3). The most 

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commonly reported systemic ARs were headache, myalgia, fatigue, chills, and fever. In the 
majority of cases, the reactions resolved spontaneously within several days. 
Laboratory abnormalities (including increases in hepatic enzymes and serum lipase levels) 
following injection were observed in clinical studies with similar mRNA-based vaccines. These 
abnormalities were without clinical symptoms or signs and returned toward baseline (Day 1) 
values over time. The clinical significance of these observations is unknown. Further details are 
provided in the current IB. 
There is a theoretical risk that active vaccination to prevent SARS-CoV-2 infection may cause a 
paradoxical increase in the risk of severe COVID-19. This possibility is based on the rare 
phenomenon of vaccine-associated ERD, which was first seen in the 1960s with 2 vaccines made 
in the same way (formalin-inactivated whole virus) and designed to protect children against 
infection with respiratory syncytial virus (Chin et al 1969) or measles virus (Fulginiti et al 1967). 
It is noteworthy that these vaccines were the result of a completely different formulation and 
with an entirely different mechanism of action than mRNA-based vaccines such as mRNA-1273. 
Disease enhancement has also been proposed as a possible explanation for cases of more serious 
disease associated with dengue vaccination (Thomas and Yoon 2019; WHO 2019). There is no 
evidence to suggest that mRNA-1273 causes enhanced disease even after widespread use in the 
general population post-authorization. Data from the ongoing Phase 3 study suggests no 
evidence of enhanced disease either, as fewer cases of severe COVID-19 and COVID-19 were 
observed in participants who received mRNA-1273 than in those who received placebo. 
In order to address this theoretical risk, animal studies have been performed in young and aged 
wild-type mice and rhesus macaques (NHPs). These studies were designed to capture 
immunogenicity endpoints that would be predictive of ERD and also to evaluate if, at protective 
or subprotective dose levels of mRNA-1273, evidence of disease enhancement would be 
observed after challenge of the animals with SARS-CoV-2. These nonclinical studies 
demonstrated that mRNA-1273 is safe and well tolerated in different animal species; is 
immunogenic; drives a robust SARS-CoV-2-specific Ab, neutralization, and Th1-directed CD4 
T-cell response; fully protects animals from challenge at dose levels as low as 1 μg/dose in mice 
and 30 μg/dose in NHPs; and does not lead to ERD at protective or subprotective dose levels 
(Corbett et al 2020a; Corbett et al 2020b). Clinical immunogenicity data from the DMID Phase 1 
study of mRNA-1273 demonstrated high levels of nAbs and Th1-polarized CD4 T-cell responses 
(Jackson et al 2020), consistent with the immunogenicity observed in the nonclinical studies. 
These data suggest that the risk of paradoxical ERD, while not eliminated, is likely to be low. 
In the context of the EUA of mRNA-1273 for individuals aged 18 years and older, there have 
been very rare reports of myocarditis and pericarditis occurring after vaccination with Moderna 
COVID-19 Vaccine. The majority of the cases have been reported in young males shortly after 

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the second dose of the vaccine. These are typically mild cases and individuals tend to recover 
within a short time following standard treatment and rest (Gargano et al, 2021). 
1.2.3 Overall Benefit/Risk Conclusion 
Based on the Phase 3 data and the results of the Phase 1 and Phase 2 studies described above, the 
Sponsor intends to study 3 dose levels (25, 50, and 100 µg) in the proposed Phase 2/3 study in 
participants 6 months to < 12 years of age (and an optional booster of 10 or 25 µg). Briefly, the 
proposed study is designed to dose escalate and age de-escalate through 3 sequential age groups 
(6 years to < 12 years, 2 years to < 6 years, and 6 months to < 2 years). Participants at each dose 
level will receive 2 doses at that dose level approximately 28 days apart. The mRNA-1273 
primary series dose levels that will be evaluated in each age group are given in Table 1. 
Table 1: Age Groups and mRNA-1273 Primary Series Dose Levels 
Age Group 
mRNA-1273 Dose Levels Planned to be 
Evaluated 
6 years to < 12 years 
251, 50, and 100 µg 
2 years to < 6 years 
252, 50, and 100 µg 
6 months to < 2 years 
25 and 50 µg 
Abbreviations: mRNA = messenger RNA. 
1  For Part 3, the 25-µg dose will be evaluated as an alternative (lower dose) dosing regimen with a primary series 
(2 doses) followed by a third dose (1 dose) 
2  The 25-µg dose will be evaluated if 100 µg is eliminated at any point during the dose-escalation process to 
maintain dose ranging for this age group. 
The study will be conducted in 3 parts. Part 1 of the study will be open-label and consist of 
dose-escalation and age de-escalation to select the dose for each age group. Part 2 of the study 
will be a placebo-controlled observer-blind evaluation of the selected dose in each age group. 
Part 3 of the study will be open-label and consist of an exploration of a lower dose for any age 
group given as a 3-dose regimen (primary series followed by a third dose). 
Immunogenicity data from participants who receive the mRNA-1273 vaccine at the selected dose 
level will be used to infer vaccine effectiveness. All participants will be followed up for 
12 months after receipt of the second injection or 12 months after their booster or third dose, if 
applicable, whichever is longer. 
Safety will be monitored throughout the study (Section 7.5). 
Given that the preliminary data from Phase 1 to 3 studies have shown no significant safety 
concerns and robust immunogenicity, mRNA-1273 may be used to address the current 
COVID-19 outbreak as a result of its uniquely rapid and scalable manufacturing process. In 
particular, a safe and effective vaccine against SARS-CoV-2 in children will help facilitate a 
return to school as an additional step towards normalization of daily activities. 

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Considering the lack of approved vaccines for COVID-19 for children < 5 years, the 
participants’ risk of COVID-19 outside the study during a pandemic, and the nonclinical and 
clinical data to date, the Sponsor considers the potential benefits of participation to exceed the 
risks. 

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2 OBJECTIVES AND ENDPOINTS 
The objectives that will be evaluated in this study and the endpoints associated with each objective 
are provided in Table 2. 
Table 2: 
Study Objectives and Endpoints 
Objectives 
Endpoints 
Primary Objectives 
Primary Endpoints 
• 
To evaluate the safety and 
reactogenicity of up to 3 dose levels 
(25, 50, and 100 µg) of mRNA-1273 
vaccine administered as 2 doses 
28 days apart in 3 age groups 
• 
Solicited local and systemic ARs through 
7 days after each injection 
• 
Unsolicited AEs through 28 days after each 
injection 
• 
MAAEs through the entire study period 
• 
SAEs through the entire study period 
• 
AESIs, including MIS-C and myocarditis 
and/or pericarditis, through the entire study 
period 
• 
To infer the efficacy of mRNA-1273 
(25, 50, and 100 µg, administered as 2 
doses 28 days apart) based on 
immunogenicity in 3 age groups 
• 
The proportion of participants with a serum 
antibody level at Day 57 ≥ antibody threshold 
of protection 
• 
If an accepted serum antibody threshold of 
vaccine protection against COVID-19 is 
available, this analysis will form the basis 
to infer efficacy 
• 
The GM value of serum antibody level and 
seroresponse rate (SRR) from Study P204 
vaccine recipients at Day 57 compared with 
those from young adult (18 to 25 years of age) 
vaccine recipients (Day 57) in the clinical 
endpoint efficacy trial (Study P301) 
• 
If a threshold is not available, efficacy will 
be inferred by establishing noninferiority 
for each age group (6 years to < 12 years, 
2 years to < 6 years, and 6 months to 
< 2 years in Study P204) compared with 
18- to 25-year old participants (Study 
P301) by both GM value of serum 
antibody levels and SRR. 
• 
For Part 3, the GM value of serum 
antibody level and SRR from Study P204 
vaccine recipients at Day 57 compared 
with those from adult (≥ 18 years of age) 

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Objectives 
Endpoints 
vaccine recipients (Day 57) in the clinical 
endpoint efficacy trial (Study P301) 
• 
Seroresponse is defined as a titer 
change from baseline (pre-Dose 1) 
below the LLOQ to ≥ 4 × LLOQ, or at 
least a 4-fold rise if baseline is ≥ LLOQ 
• 
To evaluate the safety of mRNA-1273 
booster or third dose 
• 
Solicited local and systemic ARs through 
7 days after booster or third dose 
• 
Unsolicited AEs through 28 days after booster 
or third dose injection 
• 
MAAEs through the entire study period 
• 
SAEs through the entire study period 
• 
AESIs through the entire study period 
• 
AEs leading to discontinuation from study 
participation post-booster or post-third dose 
through the last day of study participation 
• 
To evaluate safety of mRNA-1273.214 
booster dose 
• 
MAAEs through the entire study period 
• 
SAEs through the entire study period 
• 
AESIs through the entire study period 
• 
AEs leading to discontinuation from study 
participation post-booster dose or post-third 
dose through the last day of study participation 
• 
To infer effectiveness of the mRNA-
1273 booster or third dose by 
establishing noninferiority of Ab 
response after the booster dose or third 
dose in children in Study P204 
compared with postprimary series in 
adult recipients of mRNA-1273 in the 
clinical endpoint efficacy trial (Study 
P301) 
• 
GM value of post-booster (post-third dose) Ab 
in Study P204 compared with post-primary 
series (post-Dose 2) in adults (18 to 25 years) 
in Study P301 
• 
Seroresponse rate of post-booster (post-third 
dose) from baseline (pre-Dose 1) compared 
with postprimary series (post-Dose 2) from 
baseline (pre-Dose 1) in the adults (18 to 
25 years) in Study P301, using 4-fold rise 
definition 
• 
Seroresponse is defined as a titer 
change from baseline (pre Dose 1) 
below the LLOQ to ≥ 4 × LLOQ, or at 
least a 4 fold rise if baseline is ≥ LLOQ 
• For Part 3, the GM value and SRR of post-third 
dose Ab in Study P204 compared with 

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Objectives 
Endpoints 
postprimary series (post-Dose 2) from adults 
(≥ 18 years of age) in Study P301 
Secondary Objectives 
Secondary Endpoints 
• 
To evaluate the persistence of the 
immune response to mRNA-1273 
vaccine (25, 50, and 100 µg) 
• 
The GM values of SARS-CoV-2 
S protein-specific bAb on Day 1, Day 57 
(1 month after Dose 2), Day 209 (6 months 
after Dose 2), Day 394 (1 year after Dose 2), 
BD-Day 1 (at least 3 months or 6 months after 
Dose 2), BD-Day 29 (1 month after booster 
dose or third dose), BD-Day 181 (6 months 
after booster dose or third dose), and BD-Day 
366 (1 year after booster dose or third dose) 
• 
The GM values of SARS-CoV-2-specific nAb 
on Day 1, Day 57 (1 month after Dose 2), 
Day 209 (6 months after Dose 2), Day 394 
(1 year after Dose 2), BD-Day 1 (at least 
3 months or 6 months after Dose 2), 
BD-Day 29 (1 month after booster dose or 
third dose), BD-Day 181 (6 months after 
booster dose or third dose), and BD-Day 366 
(1 year after booster dose or third dose) 
• 
To evaluate the incidence of 
SARS-CoV-2 infection after 
vaccination with mRNA-1273 or 
placebo 
• 
The incidence of SARS-CoV-2 infection 
including symptomatic and asymptomatic 
infection (by serology and/or RT-PCR) 
postbaseline 
• 
SARS-CoV-2 infection will be defined in 
participants with negative SARS-CoV-2 at 
baseline: 
• 
bAb level against SARS-CoV-2 
nucleocapsid protein negative at Day 1, 
that becomes positive (as measured by 
Roche Elecsys) postbaseline, OR 
• 
Positive RT-PCR postbaseline 
• 
To evaluate the incidence of 
asymptomatic SARS-CoV-2 infection 
after vaccination with mRNA-1273 or 
placebo 
• 
The incidence of SARS-CoV-2 infection 
measured by RT-PCR and/or bAb levels 
against SARS-CoV-2 nucleocapsid protein (by 
Roche Elecsys) postbaseline in participants 
with negative SARS-CoV-2 at baseline, in the 
absence of any COVID-19 symptoms 

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Objectives 
Endpoints 
• 
To evaluate the incidence of COVID-
19 after vaccination with mRNA-1273 
or placebo. COVID-19 is defined as 
clinical symptoms consistent with 
COVID-19 AND positive RT-PCR for 
SARS-CoV-2 
• 
The incidence of the first occurrence of 
COVID-19 postbaseline, where COVID-19 is 
defined as symptomatic disease based on CDC 
case definition1  
Exploratory Objectives 
Exploratory Endpoints 
• 
To evaluate the genetic and/or 
phenotypic relationships of isolated 
SARS-CoV-2 strains to the vaccine 
sequence 
• 
Alignment of genetic sequence of viral isolates 
with that of the vaccine sequence 
• 
To describe the ratio or profile of 
specific S protein bAb relative to nAb 
in serum 
• 
Relative amounts or profiles of 
S protein-specific bAb and specific nAb titers 
in serum 
• 
To characterize the clinical profile and 
immune responses of participants with 
COVID-19 or with SARS-CoV-2 
infection 
• 
Description of clinical severity and immune 
responses of participants who are identified as 
infected by SARS-CoV-2 (COVID-19) 
• 
To assess, in a subset of participants, 
the SARS-CoV-2 S protein-specific T-
cell responses 
• 
Magnitude, phenotype, and percentage of 
cytokine-producing S protein-specific T cells, 
as measured by flow cytometry at different 
time points after vaccination relative to 
baseline 
• 
To explore asymptomatic SARS-CoV-
2 infection after vaccination with 
mRNA-1273 or placebo in participants 
with serologic evidence of infection at 
baseline 
• 
GM and GMFR of bAb levels against SARS-
CoV-2 nucleocapsid protein (quantitative IgG) 
• 
To evaluate immune response elicited 
by the primary series or booster dose or 
third dose of mRNA-1273 against 
variant(s) of interest 
• 
GM, SRR, and GMFR of Ab against variant(s) 
of concern or interest 
Abbreviations: Ab = antibody; AE = adverse event; AESI = adverse event of special interest; AR = adverse reaction; 
bAb = binding antibody; BD = booster dose; CDC = Center for Disease Control; COVID-19 = coronavirus disease 
2019; GM = geometric mean; GMFR = geometric mean fold-rise; IgG = immunoglobin G; LLOQ = lower limit of 
quantification; MAAE = medically attended adverse event; MIS-C = multisystem inflammatory syndrome in 
children; mRNA = messenger RNA; nAb = neutralizing antibody; RT-PCR = reverse transcriptase polymerase chain 
reaction; S = spike; SAE = serious adverse event; SARS-CoV-2 = severe acute respiratory syndrome coronavirus 2; 
SRR = seroresponse rate. 
1  The case definition of COVID-19 includes at least one of the following systemic symptoms: fever (temperature 
> 38ºC/≥ 100.4ºF) or chills (of any duration, including ≤ 48 hours), cough (of any duration, including ≤ 48 
hours), shortness of breath or difficulty breathing (of any duration, including ≤ 48 hours), fatigue, headache, 
myalgia, nasal congestion or rhinorrhea, new loss of taste or smell, sore throat, abdominal pain, diarrhea, nausea 
or vomiting, poor appetite or poor feeding, AND a positive test for SARS-CoV-2 by RT-PCR. 

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3 STUDY DESIGN 
3.1 General Design 
This is a Phase 2/3, three-part, open-label, dose-escalation, age de-escalation and randomized, 
observer-blind, placebo-controlled expansion study intended to infer the effectiveness of 
mRNA-1273 in children aged 6 months to < 12 years. The study population will be divided into 
3 age groups (6 years to < 12 years, 2 years to < 6 years, and 6 months to < 2 years), and up to 
3 dose levels (25, 50, and 100 µg) of mRNA-1273 will be evaluated (and a third dose or an 
optional booster of 10 or 25 µg). 
The study will be conducted in 3 parts. Part 1 of the study will be open-label and consist of 
dose-escalation and age de-escalation in approximately 1,275 participants to select the dose for 
each age group with the highest number enrolled in the oldest age group (Table 3). Part 2 of the 
study will be a placebo-controlled observer-blind evaluation of the selected dose in up to 
12,000 participants (up to 4,000 participants each in the 6 years to < 12 years, 2 years to 
< 6 years, and the 6 months to < 2 years of age groups). Part 3 will be an open-label alternative 
dosing assessment in approximately 300 participants in the 6 year to < 12 year old age group to 
assess reactogenicity and immunogenicity of a lower dose regimen. No participants in Part 1 will 
participate in Part 2 or Part 3 of the study, and no participant in Part 2 will participate in Part 3 of 
the study. 
In order to expedite the study of the safety of mRNA-1273 in school-aged children 6 years to 
< 12 years of age; Part 1 will enroll a total of approximately 375 participants per dose (both at 
the 50 and 100 µg dose levels) in this age group (6 years to < 12 years). The first 75 of these 
participants per dose will be included in the safety evaluation for dose-escalation and age 
de-escalation as well as the immunogenicity assessment needed for dose selection, as applicable. 
Additionally, approximately 300 participants per dose will be enrolled to assess for any AE 
occurring at 1% or higher. The sample size for Part 2 in this age group (6 years to < 12 years) 
will be adjusted to approximately 1700 participants. Conversely, approximately 75 participants 
in the middle age group (2 years to < 6 years) will be enrolled per dose in Part 1 for safety and 
dose selection and Part 2 will utilize the dose selected in Part 1 to inform on AEs occurring at a 
frequency of 1% or greater. In the youngest age group (6 months to < 2 years), approximately 
150 participants will be enrolled per dose in Part 1 for safety and dose selection and Part 2 will 
utilize the dose selected in Part 1 to inform on AEs occurring at a frequency of 1% or greater. 
For details, please refer to Section 7.5. 
The study will begin with the oldest age group (6 years to < 12 years) and age de-escalate as 
described under Study Progression. Each age group will begin with Part 1 and may advance to 
Part 2 and Part 3 independently. For details, please refer to the study schematic in Figure 1. 

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The mRNA-1273 investigational vaccine or placebo will be administered as 2 IM injections 
approximately 28 days apart for Part 1 and Part 2. For Part 3, the mRNA-1273 investigational 
vaccine will be administered as 3 IM injections approximately 28 days apart for the 2 doses of 
primary series followed by a third dose at least 3 months and up to 5 months after receipt of the 
second dose of the primary series. The mRNA-1273 dose levels that will be evaluated in each 
age group in Part 1, Part 2 and Part 3 of the study are given in Table 3. 
Table 3: 
Planned Age Groups and mRNA-1273 Dose Levels in Part 1, Part 2, and Part 3 
of the Study 
Age 
Group 
Part 1 
Part 2 
Part 3 
mRNA-
1273 
25 µg 
mRNA-
1273 
50 µg 
mRNA-1273 
100 µg 
Selected Dose 
Level of 
mRNA-1273 
From Part 1 
Placebo 
mRNA-1273 
25 µg 
2 doses of 
primary series + a 
third dose 
(Month 0, 1, 51) 
6 years 
to < 12 
years 
 
Study Arm 1 
(n=375)  
Study Arm 2 
(n=375) 
Study Arm 8 
(n=3,000) 
Study Arm 9 
(n=1,000) 
Study Arm 14 
(n = approximately 
300) 
2 years 
to < 
6 years 
Study Arm 
7 (Optional) 
(n=75) 
Study Arm 3 
(n=75) 
Study Arm 4 
(n=75) 
Study Arm 10 
(n= up to 
3,000) 
Study Arm 11 
(n= up to 
1,000) 
 
6 
months 
to < 2 
years 
Study Arm 
5 (n=150) 
Study Arm 6 
(n=150) 
 
Study Arm 12 
(n= up to 
3,000) 
Study Arm 13 
(n= up to 
1,000) 
 
Note: mRNA = messenger RNA. 
1. Four months post-Dose 2 ± 28 days (at least 3 months and up to 5 months post-Dose 2) 
The schematic of Study Arms and major study events is provided in Figure 1. 
Optional Booster Doses: 
Per Amendment 7, Part 1 (all ages) and 6 to < 12 year old Part 2 participants will be offered an 
optional booster dose of mRNA-1273 lower than the chosen primary series for each age group 
(Table 4), at least 6 months (Part 1 participants and Part 2 participants in Study Arm 8; Part 2 
placebo recipients from Study Arm 9, who crossed over to mRNA-1273 after unblinding) after 
Dose 2 of mRNA-1273. 
In Amendment 9, all participants in all age groups in Part 1 and Part 2 who have not yet received 
a booster dose will be offered a booster dose with mRNA-1273.214 (instead of mRNA-1273). 

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Table 4: Optional Booster Doses for Part 1 and Part 2 Participants 
Age at Time of Booster 
Booster dose 
(mRNA-1273 or 
mRNA-1273.214) 
6 to 12 years 
25 µg 
2 to < 6 years 
10 µg 
6 months to < 2 years 
10 µg 
 
Figure 1: 
Study Schema 
(a) Part 1 : Dose Escalation, Age De-escalation 
 

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(b) Part 2: Expansion 
 
Abbreviations: CMI = cell-mediated immunity; D = Day; S = spike; VTEU = Vaccine and Treatment Evaluation 
Units. 
*Expansion and primary analysis for each age group may occur at different times. 
§ Participants in each age group will be assigned to one of 5 phlebotomy cohorts. Participants in 3 of these 5 cohorts 
will provide blood specimens for immunogenicity on D1 (prior to randomization and first dose), D57, and one of 
D29 (prior to the second dose), D209, or D394 (such that each participant provides a total of 3 blood samples 
only). Participants in the Cohort D (remainder of the age group) will provide a blood sample on D1 (prior to 
randomization and before the first dose) and within 4 days of receiving Dose 2 at D30 (+3 days) for storage and 
potential future biomarker testing. A fifth cohort of participants (selected VTEU sites only) will provide blood 
samples for assessment of exploratory serology and CMI (S protein-specific T-cell responses) on D1 (prior to 
randomization and before the first dose), D43, D209, and D394. 
(c)  Part 3 
 
 
Abbreviations: D=day, M=month, N=number of participants 

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Study Progression 
Part 1 of the study will be open-label. The study will begin with enrollment of approximately 
375 participants in the 6 years to < 12 years age group (Study Arm 1) and dosing with 50 µg of 
mRNA-1273. After at least 75 participants in Study Arm 1 have completed Day 8 (1 week after 
Dose 1 of mRNA-1273 50 µg), an internal safety team (IST) will review the available safety data 
and provide a recommendation whether to escalate the dose to 100 µg in the 6 years to 
< 12 years age group (Study Arm 2; n = 375) and independently whether to begin dosing at the 
50-µg dose level in the 2 years to < 6 years age group (Study Arm 3; n = 75). After at least 
75 participants in Study Arm 1 reach Day 36 (1 week after Dose 2 of mRNA-1273 50 µg), the 
IST will again review the available safety data and provide a recommendation whether to 
administer Dose 2 of mRNA-1273 100 µg in Study Arm 2 and whether to administer Dose 2 of 
mRNA-1273 50 µg in Study Arm 3. Simultaneously, the enrollment of the remaining 
300 planned participants for both Study Arm 1 and Study Arm 2 will be ongoing. A preliminary 
safety and immunogenicity data review of Study Arm 1, and Study Arm 2 as applicable, will aid 
in the selection of a dose level for Part 2. Once all or a subset of participants from each of Study 
Arms 1 and 2 reach Day 57 (1 month after Dose 2 of mRNA-1273), an interim analysis may be 
conducted to review the safety and immunogenicity data. Cumulative safety data for 
approximately 300 participants at the selected dose level will be reviewed by the Data Safety 
Monitoring Board (DSMB) before enrollment in Part 2, and the DSMB safety review 
recommendation will enable the expansion of the 6 years to < 12 years age group (Part 2) to 
receive either mRNA-1273 at the selected dose level (Study Arm 8; n = 3,000) or placebo (Study 
Arm 9; n = 1,000). The primary analysis of immunogenicity in Part 2 for Study Arm 8 
(mRNA-1273 recipients) will be conducted after the pre-specified Immunogenicity Subset of 
participants reaches Day 57, and safety analysis will be conducted after a subset or all 
participants in Study Arms 8 and 9 reach Day 57. 
Part 3 of the study will be open-label. A total of approximately 300 participants in the 6 year to 
< 12 year old age group will be enrolled to receive 3 total doses of mRNA-1273 at 25 µg, given 
as the primary series doses at Day 1 and Day 29 followed by a third dose on Day 149/booster 
dose (BD)-Day 1 (at least 3 months and up to 5 months after the second dose in the primary 
series). The primary analysis of immunogenicity and safety in Part 3 for Study Arm 14 will be 
conducted after all treated participants reach Day 57 (for primary series). The primary analysis of 
immunogenicity and safety for the third dose will be conducted after all participants who 
received a third dose reach Day 177/BD-Day 29. 
For the middle age group (2 years to < 6 years), progression in Part 1 will be as follows: After 
75 participants in Study Arm 3 have completed Day 8 (1 week after Dose 1 of mRNA-1273 
50 µg), an IST will review the available safety data and provide a recommendation whether to 

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escalate the dose to 100 µg in the 2 years to < 6 years age group (Study Arm 4; n = 75) and 
whether to begin dosing in the 6 months to < 2 years age group at the 25-µg dose level (Study 
Arm 5; n = 150). After the 75 participants in Study Arm 3 reach Day 36 (1 week after Dose 2 of 
mRNA-1273 50 µg), the IST will review the available safety data and provide a recommendation 
whether to administer Dose 2 of mRNA-1273 100 µg in Study Arm 4 and whether to administer 
Dose 2 of mRNA-1273 25 µg in Study Arm 5. An optional Arm 7 may be enrolled in this age 
group (approximately 75 participants) at the 25-µg dose if the 100-µg dose is eliminated at any 
point during dose-escalation process, to maintain dose ranging for this age group. A preliminary 
safety and immunogenicity data review of all applicable arms will aid in the selection of a dose 
level for Part 2. Once all or a subset of participants in all applicable arms reach Day 57 (1 month 
after Dose 2 of mRNA-1273), an interim analysis may be conducted to review safety and 
immunogenicity data. A preliminary safety and immunogenicity data review of all applicable 
Arms will aid in the selection of a dose level for Part 2 and for expansion of the 2 years to 
< 6 years age group (Part 2) to receive either mRNA-1273 at the selected dose level (Study Arm 
10; n = up to 3,000) or placebo (Study Arm 11; n = up to 1,000). The primary analysis of 
immunogenicity in Part 2 for Study Arm 10 (mRNA-1273 recipients) will be conducted after a 
pre-specified Immunogenicity Subset of participants reaches Day 57, and safety analysis will be 
conducted after a subset or all participants in Study Arms 10 and 11 reach Day 57. 
For the youngest age group (6 months to < 2 years) progression in Part 1 will be as follows: In 
Study Arm 5, after 150 participants have completed Day 8 (1 week after Dose 1 of mRNA-1273 
25 µg), an IST will review the available safety data and provide a recommendation whether to 
escalate the dose to 50 µg (Study Arm 6; n = 150). After the 150 participants in Study Arm 5 
reach Day 36 (1 week after Dose 2 of mRNA-1273 25 µg), the IST will review the available 
safety data and provide a recommendation whether to administer Dose 2 of mRNA-1273 50 µg 
in Study Arm 6. Once all or a subset of participants in Study Arms 5 and 6 reach Day 57 
(1 month after Dose 2 of mRNA-1273), an interim analysis may be conducted to review the 
tolerability and immunogenicity data at each dose level. A preliminary safety and 
immunogenicity data review of Study Arm 5 and Study Arm 6, as applicable, will aid in the 
selection of a dose level for Part 2 and allow for expansion of the 6 months to < 2 years age 
group (Part 2) to receive either mRNA-1273 at the selected dose level (Study Arm 12; n = up to 
3,000) or placebo (Study Arm 13; n = up to 1,000). The primary analysis of immunogenicity in 
Part 2 for Study Arm 12 (mRNA-1273 recipients) will be conducted after the pre-specified 
Immunogenicity Subset of participants reaches Day 57, and safety analysis will be conducted 
after a subset or all participants in Study Arms 12 and 13 reach Day 57. 
In general, if a decision is made not to proceed with administration of the higher dose and/or the 
second injection at a given dose level (eg, due to safety concerns), the participants scheduled to 
receive the higher dose may receive a lower dose, and the participants who had received the 

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higher dose level as their first injection will likely be given the next lower dose level that was 
tolerated for their second injection. The dose level not tolerated in the older age group will not be 
administered in any of the younger age groups. Within an age group, if one of the dose levels is 
found to have an unacceptable tolerability profile, the age group may progress to Part 2 at a 
lower dose level. 
Part 1 and Part 2 participants who have not yet received a booster dose with mRNA-1273, nor a 
non-study vaccine booster dose will be offered an optional booster dose lower than the chosen 
primary series for each age group (Table 4), at least 3 months after Dose 2 of mRNA-1273. 
The final analysis will be performed when participants (Study Arms 1 to 14) conclude the safety 
follow-up at 12 months after their last dose (either Dose 2 or booster dose). 
The goal of the study is to support an indication for use of mRNA-1273 50 or 100 µg IM, given 
as 2 injections, approximately 28 days apart (pandemic dosing) or for the use of mRNA-1273 
25 µg given as 3 injections, approximately 28 days (primary series) and at least 3 months and up 
to 5 months (third dose) apart (lower dosing) in the 6 years to < 12 years age group; mRNA-
1273 25, 50, or 100 µg IM, given as 2 injections, approximately 28 days apart in the 2 years to 
< 6 years age group; and mRNA-1273 25 or 50 µg IM, given as 2 injections, approximately 
28 days apart in the 6 months to < 2 years age group. In addition, the study will provide support 
for the indication of a booster dose, given at the lower dosage level of the primary series, at least 
6 months, (as applicable), after Dose 2. The basis for demonstrating vaccine effectiveness is 
proposed to be met by measuring serum antibody responses in the study participants. The 
approach to inferring vaccine effectiveness will depend on whether an accepted serum antibody 
threshold conferring protection against COVID-19 has been established. If an antibody threshold 
of protection has been established, effectiveness will be inferred based on the proportion of study 
participants with serum antibody levels (on Day 57) that meet or exceed the antibody threshold. 
If an antibody threshold of protection has not been established, effectiveness will be inferred by 
demonstrating noninferiority for each age group (6 years to < 12 years, 2 years to < 6 years, and 
6 months to < 2 years in Study P204) compared with young adult (18 to 25 years of age) 
participants enrolled in the ongoing clinical endpoint efficacy trial (Study P301) by both 
geometric mean (GM) values and seroresponse rate (SRR). The statistical parameters to infer 
effectiveness are described in Section 2. 
This study in children 6 months to < 12 years of age will monitor all participants for a total of 
12 months following the second dose of vaccine or placebo, or 12 months following their booster 
or third dose, if applicable. If a COVID-19 vaccine is authorized or licensed for a specific age 
group before the end of the study, please refer to Section 3.3 for unblinding and/or cross-over 
plans. Safety assessments will include solicited ARs 7 days after each injection (ie, the day of 
injection and 6 subsequent days), unsolicited AEs (28 days after each injection), and medically 

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attended adverse events (MAAEs), SAEs, and adverse events of special interest (AESIs) 
(including MIS-C and myocarditis and/or pericarditis) through the entire study period. 
Blood samples will be collected from participants in Part 1, Part 2, and Part 3 of the study for 
assessment of immunogenicity as specified in Section 3.1.1.2. If a Day 1 (baseline) blood sample 
cannot be obtained in either Part 1, Part 2, or Part 3, the participant will be considered either a 
screen failure due to inability to satisfy inclusion criterion 3 or could be rescheduled for 
rescreening. Participants may be rescreened 1 time, either within the same screening period for 
Part 1 or Part 2 or in a new screening period of Part 2 or Part 3 if the initial screening was in Part 
1 or Part 2, respectively. If the participant is rescreened and a blood sample still cannot be 
obtained, then he/she will be considered a screen failure due to inability to satisfy inclusion 
criterion 3. Blood samples will also be tested for the development of antibodies directed against 
nonvaccine antigen (eg, antibodies against the nucleocapsid protein), which will signify infection 
with SARS-CoV-2. The incidence of SARS-CoV-2 infection among vaccine recipients and 
placebo recipients will be compared to assess the potential for mRNA-1273 to reduce the rate of 
infection in vaccine recipients. In addition, all participants will be monitored for symptoms of 
COVID-19 and scheduled for illness visits if concerning symptoms occur, and a nasal swab will 
be collected at the illness visit while Part 2 of the trial is still blinded for any age group. Once the 
trial is unblinded for all age groups and thus no placebo comparator group is available going 
forward, illness visits for COVID-19 symptoms or exposures and convalescent visits will no 
longer be required. 
3.1.1 Study Periods 
This study involves up to 8 scheduled visits including up to 6 in-person visits (if screening and 
baseline are done separately) and 2 telemedicine visits (Visit 2 and Visit 4; remote visit by means 
of telecommunication technology). An additional in clinic visit (Visit 4S) will be conducted for a 
cohort of participants from selected Vaccine and Treatment Evaluation Units (VTEU) sites on 
Day 43 (2 weeks after Dose 2 of mRNA-1273 or placebo) for exploratory serology and 
cell-mediated immunity (CMI; S protein-specific T-cell responses) in Part 2 of the study. 
If participants in Parts 1 and 2 decide to receive a booster dose, the booster study visit schedule 
(Table 15) and blood draw schedule (Table 16) will be utilized. 
The study duration for each participant will vary depending on whether they choose to receive a 
booster or not; without a booster dose, it will be approximately 14 months, which includes 
1 month for screening (Day ˗28 to Day -1), 1 month for dosing (on Day 1 and Day 29), and 
12 months of follow-up after the second dose to monitor for safety, tolerability, reactogenicity, 
immunogenicity, and efficacy. With a booster given, the study duration will be up to 24 months. 

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For Study Arm 14, the study duration will be up to 17 months, which includes 1 month for 
screening (Day -28 to Day -1), at least 5 months for dosing (on Day 1, Day 29, and a third on 
Day 149/BD-Day 1), and 12 months for follow-up after the third dose of investigational 
product (IP). 
All scheduled study visits should be completed within the respective visit windows. If the 
participant is not able to attend a study site visit as a result of the COVID-19 pandemic 
(self-quarantine or disruption of study site activities following business continuity plans and/or 
local government mandates for “stay at home” or “shelter in place”), a telemedicine visit should 
be conducted in place of the study site visit. The telemedicine visit should encompass all 
scheduled visit assessments that can be completed remotely, such as assessment for AEs and 
concomitant medications (eg, as defined in scheduled safety telephone calls). Home visits will be 
permitted for all nondosing visits, with the exception of screening, if a participant cannot visit 
the study site as a result of the COVID-19 pandemic. Home visits must be permitted by the study 
site institutional review board (IRB) and the participant’s parent(s)/legally authorized 
representatives (LAR[s]) via informed consent and have prior approval from the Sponsor (or its 
designee). 
This study will be conducted in compliance with the protocol, Good Clinical Practice (GCP), and 
all applicable regulatory requirements (Section 10.2.1). 
3.1.1.1 Screening Period 
After providing informed consent/assent, participants will undergo screening assessments to 
determine study eligibility. Screening assessments (Table 12 and Table 17) must be completed 
after the participant’s parent(s)/LAR(s) signs the informed consent form (ICF) and the 
participant, where applicable, signs the assent form. The investigator will review study entry 
criteria to determine participant eligibility during the screening period. 
Screening Visit and Day 1 may be combined on the same day. Additionally, the Screening Visit 
may be performed over multiple visits if performed within the 28-day screening window 
(Table 12 and Table 17). 
Eligible participants will enter the Treatment Period. 
3.1.1.2 Treatment and Follow-up Period 
On Day 1, after the completion of the scheduled assessments (Table 12 and Table 17), 
participants will be administered a single IM dose of the IP mRNA-1273 (25, 50, or 100 µg) or 
placebo. Placebo will be administered only to those participating in Part 2 of the study. The 
procedures for IP administration will be detailed in the mRNA-1273-P204 Pharmacy Manual. 
Participants will be closely monitored for safety and will remain at the study site for observation 

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for at least 30 minutes after dosing. On Day 29, the second dose of IP will be administered. If the 
visit for the second dose (Day 29) is disrupted and cannot be completed at Day 29 (+7 days) as a 
result of the COVID-19 pandemic (self-quarantine or disruption of study site activities following 
business continuity plans and/or local government mandates for “stay at home” or “shelter in 
place”), the visit window may be extended to Day 29 + 21 days. When the extended visit 
window is used, the remaining study visits should be rescheduled to follow the intervisit interval 
from the actual date of the second dose. Participants will be monitored for 12 months after the 
second dose of IP (or booster) or 12 months after their third dose (Part 3) of IP, if applicable and 
whichever is longer for safety, immunogenicity assessments, and biomarker samples. 
To test for the presence of SARS-CoV-2 by RT-PCR, nasal swab samples will be collected 
before the injections on Day 1, Day 29, Day 43 (if applicable per SoA), Day 57, Day 209, and 
Day 394. For Part 3, participants will have a nasal swab sample collected before the injections on 
Day 1, Day 29, Day 57, Day 149/BD-Day 1, Day 177/BD-Day 29, Day 329/BD-Day 181, and 
Day 514/BD-Day 366, according to the schedule of assessments (SoA; Table 12 and Table 17). 
Participants who test positive at baseline may receive Dose 2 as long as they remain 
asymptomatic at the time of dosing. 
During the course of the study while any age group remains blinded, participants who meet pre-
specified disease criteria that suggest possible SARS-CoV-2 infection will be asked to contact 
the study site to arrange for a prompt, thorough, and careful assessment, including a nasal swab 
sample to be tested for the presence of SARS-CoV-2 by RT-PCR. Confirmed, symptomatic 
cases of SARS-CoV-2 infection will be captured as MAAEs and, if severe, reported in an 
expedited time frame to the Sponsor (Section 7.4.4). Once the study is unblinded for every age 
group and COVID-19 surveillance is discontinued, only COVID-19 events for which the 
participants sees a health care provider will be reported (as per standard AE reporting). 
All participants will be monitored for safety and reactogenicity. All participants in Part 1 of the 
study will provide blood specimens for immunogenicity on Day 1 (prior to the first dose) and 
will also provide additional samples after the second dose of mRNA-1273 at Day 57, Day 209, 
and Day 394, except for the expansion of Arms 1 and 2 (N= ~300 participants per arm) who 
have a scheduled Day 1 blood draw and a voluntary blood draw on Day 57 only. Participants in 
each age group in Part 2 will be assigned to 1 of 5 phlebotomy cohorts. Participants in 3 of these 
5 cohorts will provide blood specimens for immunogenicity at the following time points: Day 1 
(prior to randomization and before the first dose), Day 57, and one of Day 29 (prior to the second 
dose), Day 209, or Day 394 (such that each participant provides a total of 3 blood samples only). 
Participants in the Cohort D (remainder of the age group) will provide a blood sample at Day 1 
(prior to randomization and before the first dose) and within 4 days of receiving Dose 2 at 
Day 30 (+3 days) for storage and potential future biomarker testing. For participants already 

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enrolled in Cohort D prior to Protocol Amendment 4, this blood draw will be optional and 
confirmed at time of re-consenting; for all participants newly enrolled into Cohort D under 
Amendment 4, it will be mandatory. 
A fifth cohort of participants (selected VTEU sites only) will provide blood samples for 
assessment of exploratory serology and CMI (S protein-specific T-cell responses) on Day 1 
(prior to randomization and before the first dose), Day 43, Day 209, and Day 394. Table 14 
provides the blood sampling schedule for Part 2 of the study. 
Optional Booster Doses: 
All participants in Part 1 and Part 2 who choose to receive a booster dose will provide blood 
specimens for immunogenicity and serostatus on BD-Day 1 (prior to booster dose). Subgroups of 
participants who receive a booster dose will also provide one more blood specimen post-booster 
(see Table 16 for details). 
All participants in Part 3 of the study will provide blood specimens for immunogenicity on Day 1 
(prior to the first dose) and will also provide additional samples at Day 57, Day 149/BD-Day 1 
(prior to third dose), and one month after the third dose on Day 177/BD-Day 29. The first 
150 participants (Sub-Cohort F) will also have a blood draw on Day 329/BD-Day 181; the 
second 150 participants (Sub-Cohort G) will also have a blood draw on Day 514/BD-Day 366. 
Participants and their parent(s)/LAR(s) will be instructed on the day of the first dose (Day 1) and 
reminded on the day of the second dose (Day 29) and day of booster/third dose (BD-Day 1) how 
to document and report solicited local or systemic ARs in a provided electronic diary (eDiary). 
Solicited ARs, unsolicited AEs, MAAEs, AEs leading to withdrawal, AESIs, and SAEs will be 
assessed as described in Section 7.1, according to the time points in in the SoAs (Section 10.1). 
An unscheduled visit may be prompted by reactogenicity issues, or new or ongoing AEs, and 
while Part 2 of the trial is still blinded for any age group, illness visit criteria for COVID-19. 
Illness visit criteria for COVID-19 will be applicable while Part 2 of the trial is still blinded. 
While Part 2 is still blinded for any age group, if a participant meets the pre-specified criteria of 
suspicion for COVID-19, the participant will be asked to return within 72 hours or as soon as 
possible to the study site for an unscheduled illness visit, to include a nasal swab sample (for RT-
PCR testing to evaluate for the presence of SARS-CoV-2 infection) and other clinical 
evaluations. If a study site visit is not possible, a home visit may be arranged to collect the nasal 
swab sample and conduct clinical evaluations. The study site may collect an additional nasal 
swab sample for SARS-CoV-2 testing to be able to render appropriate medical care for the study 
participant as determined by local standards of care. Additionally, clinical information will be 
carefully collected to evaluate the severity of the clinical case. 

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While Part 2 of the study is still blinded for any age group, a convalescent visit may be 
scheduled approximately 28 days (+7 days) after diagnosis of COVID-19 if there are doubts 
about the initial diagnosis (at the discretion of the investigator). At this visit, a blood sample for 
potential immunologic assessment of SARS-CoV-2 infection will be collected. 
Once the trial is unblinded for all age groups and thus no placebo comparator group is available 
going forward, illness visits for COVID-19 symptoms or exposures and convalescent visits will 
no longer be required. 
For treatment and follow-up assessments of placebo participants in the case that a COVID-19 
vaccine is authorized or licensed for a specific age group during conduct of the trial, please refer 
to Section 3.3. 
3.2 Scientific Rationale for Study Design 
This Phase 2/3 study in children 6 months to < 12 years of age is planned to understand the 
tolerability and immunogenicity of mRNA-1273 in a pediatric population. This study follows a 
pivotal Phase 3 study (Study P301) in 30,000 adults 18 years and older to demonstrate the 
tolerability, safety, and high efficacy of mRNA-1273 (100 µg on Days 1 and 29) against 
COVID-19. This pediatric study is intended to confirm safety in children between 6 months and 
12 years of age and bridge immunogenicity between children and young adults (18 to 25 years of 
age) enrolled in the pivotal adult Phase 3 study (Study P301). It is necessary to demonstrate 
noninferiority of the induced immune response in children compared with that in adults to infer 
vaccine effectiveness in this age group. 
Part 1 of the study is designed to dose escalate and age de-escalate through 3 age groups (6 years 
to < 12 years, 2 years to < 6 years, and 6 months to < 2 years). Each age group will begin dosing 
with the lowest dose planned for that group. Dose-escalation and age de-escalation will progress 
only after confirming the safety of a dose level in each age group after each IP injection. The 
placebo-controlled dose-expansion Part 2 of the study will begin only after an interim analysis is 
performed for safety and immunogenicity in each of the age groups at the selected dose level. 
With SARS-CoV-2 expected to be circulating in the general population during the study, a 
pre-defined subset of participants will provide blood samples for antibody analysis starting on 
Day 29 and continuing through 12 months after the last dose of IP. In addition, participants will 
have nasal swab samples collected at different points throughout the study, as outlined in the 
SoA (Table 12 and Table 17). Furthermore, a nasal swab sample and a blood sample will be 
taken to confirm the diagnosis of SARS-CoV-2 via RT-PCR and serology, respectively, if there 
are any signs or symptoms or an MAAE suggesting SARS-CoV-2 infection in a participant. 
Additionally, clinical information will be carefully collected to evaluate the severity of the 
clinical case. 

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As it is possible that participants are naturally exposed to SARS-CoV-2 through community 
exposure, the nasal swab samples collected before study injection and the serologic assays for 
antibody responses to nonvaccine antigen(s) may help discriminate between natural infection and 
vaccine-induced antibody responses, should such discrimination be needed. 
An optional booster dose will be offered to participants in Part 1 and Part 2 of the study. While 
this study is primarily designed to assess a 2-dose primary series of mRNA-1273 in children 
6 months to < 12 years, the emergence of the recent SARS-CoV-2 variant of concern ‘Omicron’ 
has shown in adults that protection from infection after 2 doses is less than after booster doses, 
although 2 doses still protect well against severe disease, hospitalization, and death (Johnson et 
al 2021). In Part B of Study mRNA-1273-P201 in which participants who had received 2 doses 
of 50 µg or 100 µg of mRNA-1273 6-8 months prior were administered a 50 µg booster of 
mRNA-1273, participants demonstrated enhanced immune responses compared with pre-boost 
levels and met the noninferiority criteria stipulated in the FDA Guidance on EUA for Vaccines 
to Prevent COVID-19. In addition, interim results from Study mRNA-1273-P205 show that a 
50 µg booster of mRNA-1273 increased neutralizing antibody levels against Omicron 
approximately 37-fold compared with pre-boost levels. 
3.3 Justification for Dose, Control Product, and Choice of Study Population 
Based on the Phase 3 data and the results of the Phase 1 and 2 studies described in Section 1.1.3, 
the Sponsor intends to study 3 dose levels (25, 50, and 100 µg) in the Phase 2/3 study in children 
6 months to < 12 years of age. On 18 Dec 2020, the mRNA-1273 vaccine (100 µg dose) was 
authorized by the US FDA for emergency use in individuals ≥ 18 years of age. 
As there are no licensed SARS-CoV-2 vaccines available for children 6 months to 12 years of 
age at time of enrollment in each age group, 0.9% sodium chloride will be used as a placebo 
control for the safety and immunogenicity assessments. The mRNA-1273 vaccine and placebo 
injections will look different, so administration will be blinded in Part 2 (Section 8.1). 
If a COVID-19 vaccine (mRNA-1273 or other) is authorized or licensed, eligible study 
participants (by virtue of their age) will be offered the opportunity to unblind via a phone call 
and learn what treatment they received, ideally after they have reached at least study Day 57. 
Participants who learn that they have received mRNA-1273 will continue in the study and will 
be followed per protocol. If a participant previously received placebo the participant will be 
offered cross-over vaccination with mRNA-1273 (first injection), followed by a 
second mRNA-1273 injection 28 days thereafter. The remainder of study visits will subsequently 
be performed as shown in the SoA for cross-over vaccination with mRNA-1273 if any COVID-
19 vaccine is authorized or licensed for participant’s age group (Table 13). All participants will 
continue to be followed until their end-of-study visit. In addition, participants who received a 

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lower dose in Part 1 than was ultimately approved for their respective age group in Part 2, will be 
eligible for a booster dose with the optimal dose once authorization or approval of mRNA-1273 
has been granted for their age group. If a decision is made to go outside the protocol to receive 
an EUA vaccine for the primary series, the participant will be discontinued from the study. 
In case of EUA being granted for mRNA-1273, the participants will have 4 months from date of 
EUA to elect to cross-over to mRNA-1273 within the study. Four months after the EUA date, 
cross-over will only be allowed under special circumstances (such as intermittent COVID-19 that 
would mandate a 90-day waiting period) and will need to be discussed with the Sponsor on a 
case-by-case basis. 
In case of an Emergency Use Authorization (EUA) being granted for children <5 years in the 
US, Canadian participants in the relevant age group will also qualify for unblinding and cross-
over vaccination if they wish to as of the same date, even if Health Canada has not authorized 
another COVID-19 vaccine yet in Canada. 
Participants under 6 years of age in Part 2 who have reached at least 6 months follow up after 
Dose 2 will be eligible for unblinding via a telephone call to learn which treatment they received. 
Participants who received placebo will be offered the option of cross-over vaccination with 
mRNA-1273 at that point as described above. 
Participants who initially received mRNA-1273 as their primary series will be offered a booster 
dose with mRNA-1273.214 at least 3 months after Dose 2, and those who received placebo and 
received cross-over vaccination for the primary series with mRNA-1273 will also be offered a 
booster with mRNA-1273.214 at least 3 months after cross-over Dose 2. The dosage level for 
booster doses will be lower than the chosen primary series for each age group, since the experience 
with adult boosters shows that a lower dose will allow for reductions in reactogenicity profile and 
dose sparing while still inducing a high level of neutralizing antibodies. Booster dose levels per 
age group can be found in Table 4. 
In order to allow for more comprehensive dose ranging, an additional open-label part, Part 3, is 
added per request by the health authorities. Part 3 will explore a lower dose given as a primary 
series followed by a planned third dose of the same dosage level as the primary series after at 
least 3 months and up to 5 months. 
3.4 End-of-Study Definition 
The end of the study for the full study is defined as completion of the last visit of the last 
participant in the study or the last scheduled procedure as shown in the SoAs (Section 10.1) for 
the last participant in this study. 

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4 STUDY POPULATION 
Participants will be enrolled at approximately 75 to 100 study sites in the United States and 
Canada. 
Prospective approval of protocol deviations to recruitment and enrollment criteria, also known as 
protocol waivers or exemptions, is not permitted. 
4.1 Inclusion Criteria 
Participants are eligible to be included in the study only if all the following criteria apply: 
1. The participant is male or female, 6 months to < 12 years of age at the time of 
consent/assent (Screening Visit), who is in good general health, in the opinion of the 
investigator, based on review of medical history and screening physical examination. 
2. If the participant has a chronic disease (eg, asthma, diabetes mellitus, cystic fibrosis, 
human immunodeficiency virus [HIV] infection), the disease should be stable, per 
investigator assessment, so that the participant can be considered eligible for inclusion. 
Stable diseases are those which have had no change in their status or in the medications 
required to control them in the 6 months prior to Screening Visit. 
Note: a change in medication for dose optimization (eg, insulin dose changes), change 
within class of medication, or reduction in dose are not considered signs of instability. 
3. In the investigator’s opinion, the parent(s)/LAR(s) understand and are willing and 
physically able to comply with protocol-mandated follow-up, including all procedures, 
and provide written informed consent and participants are willing to provide assent 
(Section 7.2). 
4. The participant is 2 years or older and has a body mass index (BMI) at or above the third 
percentile according to WHO Child Growth Standards at the Screening Visit 
(Section 10.2.18). 
The participant is less than 2 years of age and the participant’s height and weight are both 
at or above the 3rd percentile according to WHO Child Growth Standard at the Screening 
Visit (Section 10.2.18). 
5. Female participants of nonchildbearing potential may be enrolled in the study. 
Nonchildbearing potential is defined as premenarche. 
Special inclusion criteria for female participants who have reached menarche: 
6. Female participants of childbearing potential may be enrolled in the study if the 
participant fulfills all of the following criteria: 

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• Has a negative pregnancy test at Screening. Pregnancy test will be performed if 
deemed appropriate by the investigator. 
• Has practiced adequate contraception or has abstained from all activities that could 
result in pregnancy for at least 28 days prior to the first injection (Day 1). 
• Has agreed to continue adequate contraception or abstinence through 3 months 
following the second injection (Day 29) and the third dose in Part 3 
(Day 149/BD-Day 1). 
• Is not currently breastfeeding. 
Adequate female contraception is defined as abstinence or consistent and correct use of a US 
FDA-approved contraceptive method in accordance with the product label (Section 10.3). 
Special inclusion criteria for children 6 months to < 12 months of age 
7. The participant was born at full-term (≥ 37 weeks gestation) with a minimum birth 
weight of 2.5 kg. 
4.2 Exclusion Criteria 
Participants will be excluded from the study if any of the following criteria apply: 
1. Has a known history of SARS-CoV-2 infection within 2 weeks prior to administration of 
IP or known close contact with anyone with laboratory-confirmed SARS-CoV-2 infection 
or COVID-19 within 2 weeks prior to administration of IP. 
2. Is acutely ill or febrile 24 hours prior to or at the Screening Visit. Fever is defined as a 
body temperature ≥ 38.0°C/≥ 100.4°F. Participants who meet this criterion may have 
visits rescheduled within the relevant study visit windows. Afebrile participants with 
minor illnesses can be enrolled at the discretion of the investigator. 
3. Has previously been administered an investigational or approved CoV (eg, SARS-CoV-2, 
SARS-CoV, MERS-CoV) vaccine. 
4. Has undergone treatment with investigational or approved agents for prophylaxis against 
COVID-19 (eg, receipt of SARS-CoV-2 monoclonal antibodies) within 6 months prior to 
enrollment. 
5. Has a known hypersensitivity to a component of the vaccine or its excipients. 
Hypersensitivity includes, but is not limited to, anaphylaxis or immediate allergic 
reaction of any severity to a previous dose of an mRNA COVID-19 vaccine or any of its 
components (including polyethylene glycol [PEG] or immediate allergic reaction of any 
severity to polysorbate). 

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6. Has a medical or psychiatric condition that, according to the investigator’s judgment, 
may pose additional risk as a result of participation, interfere with safety assessments, or 
interfere with interpretation of results. 
7. Has a history of diagnosis or condition that, in the judgment of the investigator, may 
affect study endpoint assessment or compromise participant safety, specifically the 
following: 
• Congenital or acquired immunodeficiency, excluding HIV infection, as described in 
Inclusion Criteria 2 
• Chronic hepatitis or suspected active hepatitis 
• A bleeding disorder that is considered a contraindication to IM injection or 
phlebotomy 
• Dermatologic conditions that could affect local solicited AR assessments 
• Any prior diagnosis of malignancy (excluding nonmelanoma skin cancer) 
• Febrile seizures* 
*In Part 2 and Part 3 of the study, a history of a simple, single febrile seizure is 
allowed for children 6 years and older. 
8. Has received the following: 
• Any routine vaccination with inactivated or live vaccine(s) within 14 days prior to 
first vaccination or plans to receive such a vaccine through 14 days following the last 
study vaccination. 
o Note: This excludes influenza vaccine that may be given, however, not within 
14 days prior to or post-Dose 1 or Dose 2. If a participant receives an influenza 
vaccine, this should be captured within the concomitant medication electronic 
case report form (eCRF) (Section 5.5.2). 
• Systemic immunosuppressants or immune-modifying drugs for > 14 days in total 
within 6 months prior to the day of enrollment (for corticosteroids, ≥ 1 mg/kg/day or 
≥ 10 mg/day prednisone equivalent, if participant weighs > 10 kg). Participants may 
have visits rescheduled for enrollment if they no longer meet this criterion within the 
Screening Visit window. Inhaled, nasal, and topical steroids are allowed. 
• Intravenous or subcutaneous blood products (red cells, platelets, immunoglobulins) 
within 3 months prior to enrollment. 

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9. Has participated in an interventional clinical study within 28 days prior to the Screening 
Visit or plans to do so while participating in this study. 
10. Is an immediate family member, or household contact, of an employee of the study site or 
Moderna or someone otherwise directly involved with the conduct of the study. As 
applicable, family members/household contacts of employees of the larger institution or 
affiliated private practice not part of the study site may be enrolled. 
4.3 Lifestyle Restrictions 
Participants must not eat or drink anything hot or cold within 10 minutes before their 
temperature is taken. 
4.4 Screen Failures 
Screen failures are defined as participants whose parent(s)/LAR(s) provide consent and, where 
applicable, participants provide the assent to participate in the clinical study but are not 
subsequently assigned (Part 1 and Part 3) or randomly assigned (Part 2) to treatment. A 
minimum set of screen failure information is required to ensure transparent reporting of screen 
failures to meet the Consolidated Standards of Reporting Trials publishing requirements and to 
respond to queries from regulatory authorities. Minimum information includes date of informed 
consent/assent, demography, reason(s) for screen failure, eligibility criteria, and information on 
any SAE that may have occurred from Day 1 at or after dosing to the time of withdrawal. 

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5 STUDY TREATMENT 
5.1 Investigational Product Administered 
The term IP refers to mRNA-1273 (10, 25, 50, and 100 µg) vaccine or mRNA-1273.214 (10 and 
25 µg) or placebo (0.9% sodium chloride) in this study. 
mRNA-1273.214 is a bivalent vaccine containing mRNA-1273 and mRNA-1273.529 
co-formulated at a 1:1 ratio. mRNA-1273.214 injection is provided as a sterile liquid and is a 
white to off white dispersion at a concentration of 
 mg/mL in 20 mM Tris buffer with sucrose 
at pH 7.5. 
mRNA-1273 is an LNP dispersion of an mRNA that encodes the prefusion stabilized S protein 
of SARS-CoV-2 formulated in LNPs composed of 4 lipids (1 proprietary and 3 commercially 
available): the proprietary ionizable lipid SM-102; cholesterol; 
1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC); and 
1-monomethoxypolyethyleneglycol-2,3-dimyristylglycerol with PEG of average molecular 
weight 2000 (1-monomethoxypolyethyleneglycol-2,3-dimyristylglycerol polyethylene glycol 
2000 [PEG2000-DMG]). mRNA-1273 injection is provided as a sterile liquid for injection and is 
a white to off-white dispersion at a concentration of 
 mg/mL in 20 mM Tris buffer containing 
87 mg/mL sucrose and 4.3 mM sodium acetate at pH 7.5. 
mRNA-1273.529 contains mRNA CX-031302 encoding for the S-2P of the SARS-CoV-2 
Omicron variant (B.1.1.529). mRNA-1273 contains mRNA CX-024414 encoding for the S-2P of 
Wuhan Hu 1. The mRNAs are formulated in a mixture of 4 lipids common to the Sponsor’s 
mRNA vaccine platform: SM-102, cholesterol, DSPC, and PEG 2000 DMG. 
5.2 Randomization 
Random assignment of participants in Part 2 of the study will use a centralized interactive 
response technology, in accordance with pregenerated randomization schedules. Up to 
4,000 participants each in the 6 years to < 12 years, 2 years to < 6 years, and 6 months to 
< 2 years age groups will be randomized in a 3:1 ratio to the mRNA-1273 arm (n = up to 
3,000 participants in each group) or placebo arm (n = up to 1,000 participants in each group). 
5.3 Dosing and Management of mRNA-1273 Vaccine 
5.3.1 Preparation of Study Vaccine for Injection 
Each dose of IP will be prepared for each participant based on the assigned treatment, as detailed 
in the mRNA-1273-P204 Pharmacy Manual. The volume of IP injected will be 0.5 mL 
consisting of a 25-µg dose of mRNA-1273, a 50-µg dose of mRNA-1273, a 100-µg dose of 
CCI
CCI

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mRNA-1273, a 10-µg dose of mRNA-1273.214, a 25-µg dose of mRNA-1273.214, or a placebo 
(normal saline), as detailed in the mRNA-1273-P204 Pharmacy Manual. 
5.3.2 Administration of Study Vaccine 
In Part 1 and Part 2, each participant will receive 2 doses of IP by IM injection approximately 
28 days apart (Day 1 and Day 29). Part 1 and Part 2 participants who did not previously receive 
any booster doses will be offered a booster dose of IP by IM injection at least 3 months after 
Dose 2. 
For Part 3, each participant will receive 3 doses of IP by IM injections approximately 28 days 
apart for the 2 primary doses of the primary series followed by a third dose at least 3 months and 
up to 5 months after receipt of the second dose of the primary series (Day 1, Day 29, and 
Day 149/BD-Day 1). The IM injections will be administered into the deltoid muscle or 
anterolateral thigh (per investigator’s discretion), according to their assigned regimen and 
according to the procedures specified in the mRNA-1273-P204 Pharmacy Manual. 
At each visit when IP is administered, participants will be monitored for a minimum of 
30 minutes after administration. Assessments will include body temperature measurements (oral 
preferred for participants > 4 years of age, tympanic preferred for participants ≤ 4 years of age, 
but other methods acceptable in context of COVID-19 precautions) and monitoring for local or 
systemic reactions. 
Eligibility for the subsequent dose of IP will be determined by following the criteria outlined in 
Section 6. 
The study sites will be appropriately staffed with individuals with basic cardiopulmonary 
resuscitation training/certification. Either on-site resuscitation equipment and personnel or 
appropriate protocols for the rapid transport of participants to a resuscitation area or facility are 
required. 
5.3.3 Study Vaccine Delivery and Receipt 
The Sponsor or designee is responsible for the following: 
• Supplying the IP 
• Confirming the appropriate labeling of the IP, so that it complies with the legal 
requirements of the United States and Canada. 
The investigator is responsible for acknowledging the receipt of the IP by a designated staff 
member at the study site, including the following: 
• Confirming that the IP was received in good condition 

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• Confirming that the temperature during shipment from the Sponsor to the investigator’s 
designated storage location was appropriate 
• Confirming that the Sponsor has authorized the IP for use 
• Ensuring the appropriate dose level of IP is properly prepared using aseptic technique 
Further description of the IP and instructions for the receipt, storage, preparation, administration, 
accountability, and destruction of the IP are described in the mRNA-1273-P204 Pharmacy 
Manual. 
5.3.4 Study Vaccine Packaging and Labeling 
The Sponsor will provide the investigator (via the study site pharmacy) with adequate quantities 
of IP. The sterile IP is packaged in 10R glass vials with a 6.3-mL or an 8.0-mL fill volume. The 
IP will have all required labeling per regulations and will be supplied to the pharmacy in an 
unblinded manner. 
The IP will be packaged and labeled in accordance with the standard operating procedures of the 
Sponsor or its designee, Code of Federal Regulations (CFR) Title 21, Good Manufacturing 
Practice guidelines, International Council for Harmonisation (ICH) GCP guidelines, guidelines 
for Quality System Regulations, and applicable regulations. 
5.3.5 Study Vaccine Storage 
The IP must be stored at -15°C to -25°C in a secure area with limited access and be protected 
from moisture and light until it is prepared for administration (Section 5.3.1). The freezer should 
have automated temperature recording and a 24-hour alert system in place that allows for rapid 
response in case of freezer malfunction. There must be an available backup freezer. The freezer 
must be connected to a back-up generator, or an alternate plan must be in place in the event of a 
power failure. In addition, IP accountability study staff are required to keep a temperature log to 
establish a record of compliance with these storage conditions. The study site is responsible for 
reporting any IP that was not temperature controlled during shipment or during storage. Such IP 
will be retained for inspection by the monitor and disposed of according to approved methods. 
5.3.6 Study Vaccine Accountability 
It is the investigator’s responsibility that the IP accountability study staff maintain accurate 
records in an IP accountability log of receipt of all IP, study site IP inventory, IP dispensing, IP 
injections, and return to the Sponsor or alternative disposition of used and unused IP vials. 
A study site monitor will review the inventory and accountability log during study site visits and 
at the completion of each part of the study. Additional details are found in the mRNA-1273-P204 
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5.3.7 Study Vaccine Handling and Disposal 
A study site monitor will reconcile the IP inventory during the conduct and at the end of each 
part of the study for compliance. Once fully reconciled after each monitoring visit at the study 
site, and completion of each age cohort or at the end of the study, the IP can be destroyed at the 
investigational site or by a Sponsor-selected third party, as appropriate. 
Vaccine may be destroyed at the study site only if permitted by local regulations and authorized 
by the Sponsor. A certificate of destruction must be completed and sent to the Sponsor or 
designee. 
5.4 Study Treatment Compliance 
All doses of IP will be administered at the study site under direct observation of medically 
qualified study staff and appropriately recorded (date and time) in the eCRF. Qualified study site 
staff will confirm that the participant has received the entire dose of IP. If a participant does not 
receive IP or does not receive all of the planned doses, the reason for the missed dose will be 
recorded. Data will be reconciled with study site accountability records to assess compliance. 
Participants who miss the second dose due to noncompliance with the visit schedule and not due 
to a safety pause will still be required to follow the original visit and testing schedule as 
described in the protocol and their regimen schedule. Unless consent/assent is withdrawn, a 
participant who withdraws or is withheld from receiving the second dose will remain in the study 
and complete all safety and immunogenicity assessments required through the participant’s last 
scheduled study visit. 
The study site staff are responsible for ensuring that participants comply with the allowed study 
visit windows. If a participant misses a visit, every effort should be made to contact the 
participant and complete a visit within the defined visit window. If a participant does not 
complete a visit within the time window, that visit will be classified as a missed visit and the 
participant will continue with subsequent scheduled study visits. All safety requirements of the 
missed visit will be captured and included in the subsequent visit. 
5.5 Prior and Concomitant Medications 
5.5.1 Prior Medications and Therapies 
Information about prior medications (including any prescription or over-the-counter medications, 
vaccines, or blood products) taken by the participant within the 28 days before his/her 
parent(s)/LAR(s) provided informed consent and the participant provided assent (or as 
designated in the inclusion/exclusion requirements) will be recorded in the participant’s eCRF. 
 

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5.5.2 Concomitant Medications and Therapies 
At each study visit, study site staff must question the participant and/or the participant’s 
parent(s)/LAR(s) regarding any medications taken and vaccinations received by the participant 
and record the following information in the eCRF: 
• All nonstudy vaccinations administered within the period starting 14 days before the first 
dose of IP and through 14 days after the last dose of IP. 
• Seasonal influenza vaccine administered for the current influenza season (typically 
October through April in the Northern Hemisphere). 
• All concomitant medications taken through 28 days after each dose of IP. Antipyretics 
and analgesics taken prophylactically (ie, taken in the absence of any symptoms in 
anticipation of an injection reaction) will be recorded as such. 
• Any concomitant medications used to prevent or treat COVID-19 or its symptoms. 
− Note: if any participant who has received at least one dose of mRNA-1273 received 
another COVID-19 vaccine outside of the trial (eg, as a booster dose), please record 
this under concomitant medications; the participant may remain in the trial and will 
continue to be followed per protocol. 
• Any concomitant medications relevant to or for the treatment of an SAE or an MAAE. 
Participants will be asked in the eDiary if they have taken any antipyretic or analgesic to treat or 
prevent fever or pain within 7 days after each IP dose, including on the day of dosing. Reported 
antipyretic or analgesic medications should be recorded in the source document by the study site 
staff during the post-injection period of the study visits or via other participant interactions 
(eg, telephone calls). 
Data regarding nutritional supplements, eg, vitamins, probiotics, and herbal supplements, will 
not be collected. 
Concomitant medications (including vaccinations) will be coded using the WHO Drug 
Dictionary. If a participant takes a prohibited drug therapy, the investigator and the contract 
research organization’s (CRO’s) medical monitor will make a joint decision about continuing or 
withholding further injection of the participant based on the time the medication was 
administered, the drug’s pharmacology and pharmacokinetics, and whether use of the medication 
will compromise the participant’s safety or interpretation of the data. It is the investigator’s 
responsibility to ensure that details regarding concomitant medications are adequately recorded 
in the eCRF. 

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5.5.3 Concomitant Medications and Vaccines That May Lead to the Elimination of a 
Participant from Per Protocol Analyses 
The use of the following concomitant medications and/or vaccines will not require withdrawal of 
the participant from the study but may determine a participant’s eligibility to receive a second 
dose or be included in the per protocol (PP) analysis (analysis sets are described in Section 8.4): 
• Any investigational or nonregistered product (drug or vaccine) other than the IP used 
during the study period. 
• Immunosuppressants or other immune-modifying drugs administered chronically 
(ie, > 14 days in total) during the study period. For corticosteroids, receipt of prednisone 
or the equivalent at a dose of ≥ 1 mg/kg/day (or ≥ 10 mg/day if participant 
weighs > 10 kg) is not permitted. Inhaled, nasal, and topical steroids are allowed. 
• Long-acting immune-modifying drugs administered at any time during the study period 
(eg, infliximab). 
• Immunoglobulins and/or any Ab-containing blood products administered during the 
study period. 
5.6 Intervention After the End of the Study 
Any SAE, including death, occurring after the end of the study, and considered to be caused by 
the IP must be reported to the Sponsor. 

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6 DELAYING OR DISCONTINUING STUDY TREATMENT AND 
PARTICIPANT WITHDRAWAL FROM THE STUDY 
6.1 Criteria for Delay of Vaccine Administration 
6.1.1 Individual Participant Criteria for Delay of Study Vaccination 
Body temperature (oral preferred for participants > 4 years of age or tympanic preferred for 
participants ≤ 4 years of age, but other methods are acceptable in context of COVID-19 
precautions) must be measured on dosing visits before vaccine administration. The following 
events constitute criteria for delay of injection, and if any of these events occur at the time 
scheduled for dosing, the participant may receive the study injection at a later date within the 
time window specified in the SoAs (Section 10.1), or the participant may be discontinued from 
dosing at the discretion of the investigator (Section 6.2): 
• Acute moderate or severe infection with or without fever at the time of dosing 
• Fever, defined as body temperature ≥ 38.0°C/≥ 100.4°F at the time of dosing 
Participants with a minor illness without fever, as assessed by the investigator, can be 
vaccinated. 
Participants with a fever of ≥ 38.0°C/≥ 100.4°F will be contacted within the time window 
acceptable for participation and re-evaluated for eligibility. If the investigator determines that the 
participant’s health on the day of dosing temporarily precludes injection, the visit should be 
rescheduled within the allowed interval for that visit. 
If a participant was exposed to a household contact (excluding school or other exposures) who 
tested positive for SARS-CoV-2 after the participant received the first dose, the administration of 
the second dose may be delayed to allow for at least 14 days between the positive test or the last 
day of symptoms (if present) of the household contact and Dose 2 as long as the participant 
remains asymptomatic. 
If a participant tests positive for SARS-CoV-2 after having received Dose 1 but remains 
asymptomatic and the second dose is due before 14 days after the positive test, administration of 
the second dose may be delayed to allow for at least 14 days between the participant’s positive 
test and Dose 2 as long as participant remains asymptomatic. The same applies for the interval 
between Dose 2/cross-over Dose 2 and a booster dose/third dose. 
If a participant tests positive for SARS-CoV-2 after having received Dose 1 and develops 
symptoms of COVID-19, the participant may still receive a second dose, but the second dose 
should be delayed until approximately 90 days after diagnosis with COVID-19. The same applies 
for the interval between Dose 2/cross-over Dose 2 and a booster dose/third dose. 

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If a participant takes a prohibited drug therapy, an injection could be delayed within the visit 
window based on the joint decision of the investigator and the CRO’s medical monitor 
(Section 5.5.2). 
If unforeseen circumstances out of the control of the participant’s family or the study site 
(eg, extreme weather, such as hurricanes) render it impossible for the participant to receive the 
second dose within the specified window, Dose 2 may be delayed at the principal investigator’s 
discretion but should be administered as soon as possible thereafter. 
6.2 Discontinuing Study Vaccination 
Participants can discontinue study injection (ie, refuse the second dose) for any reason, without 
prejudice to further treatment the participant may need to receive. 
The investigator, in consultation with the Sponsor’s medical monitor, may withhold a participant 
from further injection under the following circumstances: 
• The participant becomes pregnant. 
• The participant’s parent(s)/LAR(s) withdraw consent or the participant withdraws 
assent. 
• An RT-PCR result from an illness visit (Section 7.1.5) is positive for SARS-CoV-2 and 
the participant is symptomatic at the time of next injection. 
• The participant develops, during the course of the study, symptoms or conditions listed 
in the exclusion criteria (Section 4.2). 
• The participant experiences an AE (other than solicited reactogenicity) after injection 
that is considered by the investigator to be related to IP (Section 7.4.9) and is of Grade 3 
(severe) or greater severity. 
• The participant experiences an AE or SAE that, in the judgment of the investigator, 
requires IP withdrawal due to its nature, severity, or required treatment, regardless of the 
causal relationship to vaccine. 
• The participant experiences an AESI (eg, MIS-C and myocarditis and/or pericarditis). 
• The participant experiences a clinically significant change in general condition that, in 
the judgment of the investigator, requires vaccine withdrawal. 
• The participant experiences anaphylaxis (described in Section 7.4.4) clearly related to 
IP. 
• The participant experiences generalized urticaria related to IP. 

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The reason(s) for withdrawal from further injection will be recorded in the eCRF. 
If a participant takes a prohibited drug therapy, the investigator could withhold the second dose 
based on a joint decision of the investigator and the CRO’s medical monitor (Section 5.5.2). 
Every reasonable attempt should be made to follow-up with participants for safety throughout 
the entire scheduled study period according to their regimen, even if the participant does not 
receive the second dose or misses one or more visits. Unless the participant’s parent(s)/LAR(s) 
withdraw consent or the participant withdraws assent, they are expected to remain in the study 
and complete all scheduled visits and assessments. 
6.3 Participant Discontinuation/Withdrawal from the Study 
Participants who withdraw or are withdrawn from the study will not be replaced. A “withdrawal” 
from the study refers to a situation wherein a participant does not return for the final visit 
planned in the protocol. 
The participant’s parent(s)/LAR(s) can withdraw consent or the participant can withdraw assent 
and withdraw from the study at any time, for any reason, without prejudice to further treatment 
the participant may need to receive. The investigator will request that the participant complete all 
study procedures pending at the time of withdrawal. 
If a participant desires to withdraw from the study because of an AE, the investigator will try to 
obtain agreement to follow-up with the participant until the event is considered resolved or stable 
and will then complete the end of the study eCRF. 
Information related to the withdrawal will be documented in the eCRF. The investigator will 
document whether the decision to withdraw a participant from the study was made by the 
participant or by the investigator, as well as which of the following possible reasons was the 
cause for withdrawal: 
• AE (specify) 
• SAE (specify) 
• Death 
• Lost to follow-up (LTFU) 
• Physician decision (specify) 
• Pregnancy 
• Protocol deviation 
• Study terminated by Sponsor 

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• Withdrawal of consent by participant’s parent(s)/LAR(s) or withdrawal of assent by the 
participant (specify) 
• Other (specify) 
Participants who are withdrawn from the study because of AEs (including AESIs and SAEs) 
must be clearly distinguished from participants who are withdrawn for other reasons. 
Investigators will follow-up with participants who are withdrawn from the study as result of an 
SAE or AE until resolution of the event. 
A participant who withdraws from the study may request destruction of any samples taken and 
not tested, and the investigator must document this in the study site study records. 
If the participant’s parent(s)/LAR(s) withdraw consent or the participant withdraws assent for 
disclosure of future information, the Sponsor may retain and continue to use any data collected 
before such a withdrawal of consent/assent (Section 10.2.10). 
The Sponsor will continue to retain and use all research data that have already been collected for 
the study evaluation, unless the participant has requested destruction of these samples. All 
biological samples that have already been collected may be retained and analyzed at a later date 
(or as permitted by local regulations). 
Unblinding of still blinded participants based only on parental/LAR request and not related to a 
safety event or health concern before the participant has reached at least 6 months of follow up 
after Dose 2 will not be permitted to protect the data integrity of the blinded portion of the study. 
If a parent/LAR wishes to withdraw their child from the study, they may withdraw at any time 
but will only be able to learn the treatment group assignment once their child has reached at least 
6 months of follow up after Dose 2 or an unblinding trigger for the entire applicable age group is 
reached (eg, EUA granted for mRNA-1273 or a competitor vaccine). 
6.3.1 End-of-Study Visit (Prior to Day 394 or Day 514/BD-Day 366) 
Once a participant withdraws from the study, the investigator (or delegate) should confirm all 
ongoing AEs have been addressed and answer any additional questions the participant may have; 
this may be done via a telephone call. The communication should be documented in the source. 
The End-of-Study/Study Discontinuation eCRF page must be completed. 
6.4 Study Pause Rules 
The investigators, study medical monitor, and Sponsor will monitor for events that could trigger 
a study pause. Study pause rule criteria, events, and thresholds are described in Table 5. 

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Table 5: 
Pause Rule Criteria, Events, and Thresholds 
Pause Rule 
Criterion 
Event 
Participant Threshold for 
Triggering Study Pause 
1 
Any death due to SARS-CoV-2 infection 
≥ 1 
2 
Any SAE or Grade 4 AE that cannot be 
reasonably attributed to a cause other than 
vaccination 
≥ 1 
3 
ICU Admission due to COVID-19 
≥ 1 
41,2 
Individual Grade 3 or higher solicited local AR 
lasting ≥ 24 hours and occurring within 7 days of 
injection (Days 1-7) 
At least 2 participants 
and ≥ 5% of the dosed 
participants in an age 
group 
51,2 
Individual Grade 3 or higher solicited systemic 
AR lasting ≥ 24 hours and occurring within 7 
days of injection (Days 1-7) 
At least 2 participants 
and ≥ 10% of the 
enrolled participants in 
an age group  
61,2 
Any ≥ Grade 3 or higher unsolicited AE that 
cannot be reasonably attributed to a cause other 
than vaccination 
At least 2 participants 
and ≥ 5% of the enrolled 
participants in an age 
group  
Abbreviations: AE = adverse event; AR = adverse reaction; COVID-19 = coronavirus disease 2019; ICU = intensive 
care unit; SAE = serious adverse event; SARS-CoV-2 = severe acute respiratory syndrome coronavirus 2. 
1  “Individual AR” is defined as 1 AR type, eg, pain, erythema, or headache could each be an “individual AR.” 
2  Events in participants receiving booster doses will be considered separately from the events during the primary 
vaccination series. 
If any of the thresholds for a study pause is met, the Sponsor will immediately suspend further 
enrollment and/or study dosing by notifying all investigators. Such a suspension will remain in 
force until the threshold events are reviewed by the DSMB and a recommendation to continue is 
provided to the Sponsor. 
The investigator or designee is responsible for reporting to the Sponsor, via the electronic data 
capture (EDC) system, each event that potentially meets any pause rule criterion within 24 hours 
of observation. If an SAE assessed as related to IP by the investigator is reported at any point, the 
Sponsor’s medical monitor is responsible for a rapid assessment (with the Sponsor’s Medical and 
Safety team) of whether pause rule # 2 has been met; the Sponsor medical monitor may consult 
with the DSMB chair as an independent entity to make that determination, as described in the 
DSMB charter. 
The Sponsor will inform the DSMB of any event that meets any pause rule criterion. The DSMB 
will review all available study data to help adjudicate such events in accordance with the DSMB 
charter. 

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The Sponsor will notify the Center for Biologics and Evaluation Research within 48 hours in the 
event of a study pause. In the event of a study pause, all safety and immunogenicity assessments 
will continue per protocol. The window allowance for injection visits may be extended by an 
additional 7 days (ie, + 21 days) for affected participants at the discretion of the Sponsor. 
6.5 Lost to Follow-up 
A participant will be considered LTFU if he or she repeatedly fails to return for scheduled visits 
without stating an intention to withdraw consent/assent and is unable to be contacted by the 
study site. The following actions must be taken if a participant fails to return to the clinic for a 
required study visit: 
• The study site staff must attempt to contact the participant and reschedule the missed 
visit as soon as possible, counsel the participant and his/her parent(s)/LAR(s) on the 
importance of maintaining the assigned visit schedule and ascertain whether the 
participant wishes to and/or should continue in the study. 
• Before a participant is deemed LTFU, the investigator or designee must make every 
effort to regain contact with the participant (where possible, 3 telephone calls and, if 
necessary, a certified letter to the participant’s last known mailing address or local 
equivalent methods). These contact attempts (eg, dates of telephone calls and 
registered letters) should be documented in the participant’s medical record. 
• A participant who continues to be unreachable or continues to be noncompliant with 
study visits or procedures will be considered to have withdrawn from the study. 
• A participant should not be considered LTFU until due diligence has been completed. 

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7 STUDY ASSESSMENTS AND PROCEDURES 
Before performing any study procedures, all potential participants and/or participants’ 
parent(s)/LAR(s) will sign an ICF (as detailed in Section 10.2.6). Participants will undergo study 
procedures at the time points specified in the SoAs (Section 10.1). A participant can also be seen 
for an unscheduled visit at any time during the study. An unscheduled visit may be prompted by 
reactogenicity issues, illness visit criteria for COVID-19 (as applicable while Part 2 of study is 
still blinded for any age group), or new or ongoing AEs. The study site also has the discretion to 
make reminder telephone calls or send text messages to inform the participant and/or 
participant’s parent(s)/LAR(s) about visits, review eDiary requirements, or follow-up on ongoing 
or outstanding issues. 
In accordance with “FDA Guidance on Conduct of Clinical Trials of Medical Products during 
COVID-19 Public Health Emergency” (DHHS 2020), investigators may convert study site visits 
to home visits or telemedicine visits with the approval of the Sponsor. Such action should be 
taken to protect the safety and well-being of study participants and study site staff or to comply 
with state or municipal mandates. 
General considerations for study assessments and procedures include the following: 
• Protocol waivers or exemptions are not allowed. The study procedures and their timing 
must be followed as presented in in the SoAs (Section 10.1). Adherence to the study 
design requirements is essential and required for study conduct. 
• Immediate safety concerns should be discussed with the Sponsor immediately upon 
occurrence or awareness to determine if the participant should continue study treatment 
or participation in the study. 
• All screening evaluations must be completed and reviewed to confirm that potential 
participants meet all eligibility criteria. The investigator will maintain a screening log to 
record details of all participants screened and to confirm eligibility or record reasons for 
screening failure, as applicable. 
• Procedures conducted as part of the participant’s routine clinical management 
(eg, pregnancy test) and obtained before signing of the ICF may be utilized for screening 
or baseline assessments provided the procedures met the protocol-specified criteria and 
were performed within the time frame defined in in the SoAs (Section 10.1). 
 
 
 

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7.1 Safety Assessments and Procedures 
Safety assessments will include monitoring and recording of the following for each participant, 
according to the SoAs (Section 10.1): 
• Solicited local and systemic ARs (Section 7.4.3) that occur during the 7 days following 
each injection (ie, the day of injection and 6 subsequent days). Solicited ARs will be 
recorded daily using eDiary (Section 7.1.1). 
• Unsolicited AEs observed or reported during the 28 days following each injection (ie, the 
day of injection and 27 subsequent days). Unsolicited AEs are defined in Section 7.4.1. 
• AEs leading to discontinuation from dosing and/or study participation from Day 1 
through the last day of study participation. 
• MAAEs (Section 7.4.4) from first dose on Day 1 through the entire study period. 
• SAEs (Section 7.4.2) from first dose on Day 1 through the entire study period. 
• AESIs (Section 7.4.5) including MIS-C and myocarditis and/or pericarditis, through the 
entire study period. 
• Physical examination findings (Section 7.1.4). 
• Assessments for SARS-CoV-2 infection from Day 1 through study completion 
(Section 7.1.5). 
• Details of all pregnancies in female participants after the start of study treatment and until 
the end of their participation in the study (Section 7.4.6). 
7.1.1 Use of Electronic Diaries 
At the time of consent, participants’ parent(s)/LAR(s) must confirm they will be willing to 
complete an eDiary using either an application downloaded to their smartphone or using a device 
that is provided at the time of enrollment. Before enrollment on Day 1, participants’ 
parent(s)/LAR(s) will be instructed to download the eDiary application or will be provided an 
eDiary device to record solicited ARs (Section 7.4.3) on Day 1. Based on availability, 
smartphone devices may be provided to those participants’ parent(s)/LAR(s) who do not have 
their own device to use for eDiary activities. 
At each injection visit, participants’ parent(s)/LAR(s) will be instructed (Day 1) or reminded 
(Day 29, BD-Day 1, if applicable) on thermometer (oral/tympanic) usage to measure body 
temperature, ruler usage to measure injection site erythema and swelling/induration (hardness), 
and assessment for localized axillary swelling or tenderness on the same side as the injection 
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At each injection visit, participants’ parent(s)/LAR(s) will record data into the eDiary starting 
approximately 30 minutes after injection under the supervision of the study site staff to ensure 
successful entry of assessments. The study site staff will perform any retraining as necessary. 
Participants’ parent(s)/LAR(s) will continue to record data in the eDiary after they leave the 
study site, preferably in the evening and at the same time each day, on the day of injection and 
for 6 days following injection. 
Participants’ parent(s)/LAR(s) will record the following data in the eDiary: 
• Solicited local and systemic reactogenicity ARs, as defined in Section 7.4.3, that occur on 
the day of each vaccine administration and during the 7 days after vaccine administration 
(ie, the day of injection and 6 subsequent days). If a solicited local or systemic AR 
continues beyond Day 7 after vaccination, the participant’s parent(s)/LAR(s) will be 
prompted to capture details of the solicited local or systemic AR in the eDiary until it 
resolves or the next IP injection occurs, whichever occurs first. Capture of details of ARs 
in the eDiary should not exceed 28 days after each vaccination. Adverse reactions 
recorded in the eDiary beyond Day 7 should be reviewed by the study site staff either 
during the next scheduled telephone call or at the next study site visit. 
• Daily oral (for participants > 4 years of age) or tympanic (for participants ≤ 4 years of 
age) body temperature measurement should be performed at approximately the same time 
each day using the thermometer provided by the study site. If body temperature is taken 
more than once in a given day, only the highest temperature reading should be recorded. 
• Measurement, as applicable, for solicited local ARs (injection site erythema and 
swelling/induration); the size measurements will be performed using the ruler provided 
by the study site. 
• Any medications taken to treat or prevent pain or fever on a day of injection or for the 
next 6 days. 
The eDiary will be the only source document allowed for solicited systemic or local ARs 
(including body temperature measurements). Participants’ parent(s)/LAR(s) will be instructed to 
complete eDiary entries daily. The participant’s parent(s)/LAR(s) will have a limited window on 
the following day to complete assessments for the previous day; quantitative temperature 
recordings and measurement of any injection site erythema or swelling/induration reported on 
the following day may be excluded from the analyses of solicited ARs. 
Any new safety information reported during safety telephone calls or at study site visits 
(including a solicited reaction) that is not already captured in the eDiary will be described in the 
source documents as a verbally reported event. An event reported in this manner must be 
described as a solicited event and entered on the solicited AR eCRF. 

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Study site staff will review eDiary data with participants’ parent(s)/LAR(s) at telemedicine visits 
7 days after each injection. 
The eDiary will also be used every 4 weeks, starting at Day 71 through Day 183 and again 
starting at Day 223 through Day 363 for Parts 1 and 2 and starting Day 71 through Day 183 and 
again starting at Day 191 through Day 303 for Part 3, to capture the occurrence of AEs, MAAEs, 
SAEs, AESI, or AEs leading to withdrawal. 
As specified in the SoAs (Section 10.1), where applicable, the eDiary will prompt the 
participant’s parent(s)/LAR(s) to complete an eDiary questionnaire that collects the following 
data: 
• Changes in health since last completing the questionnaire or since in contact with the 
study site 
• Any MAAEs, AESIs, or SAEs 
• Known close contact with someone in the household who has known COVID-19 or 
SARS-CoV-2 infection. Per the CDC, “close contact” to someone with COVID-19 is 
defined as follows: 
− Being within 6 feet for a total of 15 minutes or more 
− Providing care at home 
− Having direct physical contact (hugged or kissed them) 
− Sharing eating or drinking utensils 
− Being sneezed or coughed upon or getting respiratory droplets on the participant 
• Any experience of symptoms of COVID-19 
If an eDiary record results in identification of relevant safety events according to the study 
period or of symptoms of COVID-19, a follow-up safety telephone call will be triggered. 
Completion of eDiary questionnaires will alternate with safety telephone calls (Section 7.1.2) as 
the procedure for safety follow-up approximately every 4 weeks; these safety telephone calls will 
take place from Day 85 through Day 197 and again from Day 237 through Day 377 (Table 12). 
For Part 3, these safety telephone calls will take place from Day 85 through Day 197 and again 
from Day 205 through Day 317 (Table 17). 
Ancillary Supplies for Participant Use 
Study sites will distribute Sponsor-provided oral or tympanic thermometers and rulers for use by 
participants’ parent(s)/LAR(s) in assessing body temperature and injection site reactions for 

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recording solicited ARs in electronic diaries (eDiary). Based on availability, smartphone devices 
may be provided to those participants’ parent(s)/LAR(s) who do not have their own device to use 
for eDiary activities. 
7.1.2 Safety Telephone Calls 
A safety telephone call is a telephone call made to the participants’ parent(s)/LAR(s) by trained 
study site personnel. This call will follow a script, which will facilitate the collection of relevant 
safety information. Safety telephone calls follow a schedule for each participant as indicated in 
in the SoAs (Section 10.1). The participants’ parent(s)/LAR(s) will be interviewed according to 
the script about the occurrence of AEs, MAAEs, SAEs, AESI, AEs leading to study withdrawal, 
concomitant medications associated with those events, and any nonstudy vaccinations 
(Section 7.4.7). In addition, study personnel will collect information on known participant 
exposure to someone with known COVID-19 or SARS-CoV-2 infection and on participant 
experience of COVID-19 symptoms. All safety information collected from the telephone contact 
must be documented in source documents as described by the participant’s parent(s)/LAR(s) and 
not documented on the script used for the safety telephone contact. As noted in Section 7.1.1, an 
unscheduled follow-up safety telephone call may be triggered if an eDiary record results in 
identification of a relevant safety event. 
7.1.3 Safety Laboratory Assessments 
No scheduled laboratory assessments for safety are planned. This is based on the absence of 
clinically significant abnormal laboratory findings in the Phase 1 and Phase 2 studies of 
mRNA-1273 in adults. 
A point-of-care urine pregnancy test will be performed, if deemed appropriate by the 
investigator, at the Screening Visit and before each vaccine dose in female participants of 
childbearing potential. At any time during the study, a pregnancy test either via blood or point-
of-care urine can be performed, at the discretion of the investigator. 
Febrile participants at dosing visits (fever is defined as a body temperature ≥ 38.0°C/≥ 100.4°F) 
may have visits rescheduled within the relevant study visit windows. Afebrile participants with 
minor illnesses may receive the IP at the discretion of the investigator. 
7.1.4 Physical Examinations 
A full physical examination, including body temperature (oral preferred for participants > 4 years 
of age, tympanic preferred for participants ≤ 4 years of age, but other methods are acceptable in 
context of COVID-19 precautions), length/height and weight, will be performed at the Screening 
Visit or on Day 1. For participants receiving booster doses, symptom-directed physical 
examination will be performed on BD-Day 1. The full examination will include assessment of 

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skin, head, ears, eyes, nose, throat, neck, lungs, heart, abdomen, lymph nodes, and 
musculoskeletal system/extremities. Any clinically significant finding identified during a study 
visit should be reported as an MAAE. 
Symptom-directed physical examinations will be performed per the SoAs found in Section 10.1 
(Appendix 1) and may be performed at other time points at the discretion of the investigator. 
Body temperature (oral/tympanic) should be measured on each injection day prior to injection. 
On each injection day before injection and again 7 days after injection (ie, the day of injection 
and 6 subsequent days), the injection site should be examined. Any clinically significant finding 
identified during a study visit should be reported as an MAAE. 
Participants who are febrile (body temperature ≥ 38.0°C/≥ 100.4°F) before injection on Day 1 or 
Day 29 must have the visit rescheduled within the relevant visit window to receive the injection. 
Afebrile participants with minor illnesses may be injected at the discretion of the investigator. 
Body mass index will be calculated for children ≥ 2 years of age at the Screening Visit only. 
7.1.5 Assessment for SARS-CoV-2 Infection 
Study participants will have nasal swab samples collected for SARS-CoV-2 testing at the time 
points specified in in the SoAs (Section 10.1). 
While Part 2 of the study is still blinded for any age group, a study illness visit (study site visit or 
home visit) will be arranged within 72 hours or as soon as possible if a participant experiences 
any of the following: 
• Signs or symptoms of SARS-CoV-2 infection as defined by the CDC (CDC 2020b) 
• MAAE suggesting a SARS-CoV-2 infection 
For asymptomatic children, a study visit (study site visit or home visit) will be arranged 
approximately 7 days after the diagnosis of COVID-19 in a household, if a participant 
experiences the following: 
• Exposure (close contact [definition in Section 7.1.1]) to an individual in the household 
confirmed to be infected with SARS-CoV-2. For the purpose of calculating the day of the 
study visit, 7 days will be calculated from the first day of illness or positive COVID-19 
test, whichever day is earlier, in a household contact. 
A negative local diagnostic test (NAAT) may be used to satisfy the study visit, provided that the 
participant remains asymptomatic for COVID-19 and the test is collected at least 5 days after the 
index case in a household. 
In accordance with CDC guidance on COVID-19 testing, exposure visits are not required for 
participants who are within 90 days of a COVID-19 illness (from the date of positive COVID-19 

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test). Illness visits should still be performed, even if within 90 days of a previous COVID-19 
infection, for participants with signs/symptoms consistent with COVID-19. 
During a surge in SARS-CoV-2 infections across the US and Canada and given the changing 
practice of using home tests to diagnose SARS-CoV-2 infections, the following alternative 
process may be used for assessment of SARS-CoV-2 infection: 
If an illness visit is not feasible due to COVID-19 related restrictions at site or in the wider 
community, a telehealth visit or phone call combined with a local diagnostic test to be recorded 
under an unscheduled visit eCRF page, can substitute for a clinic visit. 
If due to COVID-19 related restrictions in the community, the participant’s LAR performed a 
home test rather than obtaining a test performed by a health care professional, the following 
process should apply: 
• If the participant is asymptomatic but was exposed to a positive household member, and 
the home test obtained within the appropriate window (4-6 days post-exposure) was 
negative, the investigator may report the result of the home test under the local 
diagnostic lab page as an unscheduled visit and forego the illness visit. 
• If the participant reports symptoms but home test was negative, the investigator may 
report symptoms as ‘URI’ or other appropriate AE and report the negative home test on 
the local diagnostic lab page for an unscheduled visit, and forego the illness visit. 
• If the participant reports symptoms, or is asymptomatic after a household exposure, and 
the home test was positive, the investigator should encourage the family to seek 
confirmatory PCR-based testing at a local testing center or return to site for an illness 
visit. 
− If a local confirmatory PCR-based test is obtained, the investigator may report the 
result under an unscheduled visit and forego the illness visit. 
− If due to COVID-19 related restrictions at the site or in the community, neither a local 
test nor an illness visit is feasible, the investigator may report the result of the home 
test under the local diagnostic lab page as an unscheduled visit and forego the illness 
visit. 
If the participant had a known exposure (close contact) to COVID-19 (eg, exposure to someone 
with confirmed COVID-19 in the household), it will be captured in the COVID-19 exposure 
form. 
Additionally, clinical information will be carefully collected to evaluate the severity of the 
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At each study illness visit, an initial assessment will be performed to determine general 
appearance. This initial assessment may be performed by physicians, advanced practice nurses, 
physician assistants, or registered nurses. If indicated, a physical examination by a study 
clinician (MD, DO, NP, or PA experienced in pediatric examination) may occur. 
The study illness visit (study site visit or home visit) may collect additional clinical information, 
including assessments such as updated medical history, physical examination, blood sampling 
for clinical laboratory testing, and nasal swab sampling for viral RT-PCR to evaluate the severity 
of the clinical case. Radiologic imaging studies may be conducted. Study site may also collect an 
additional nasal swab sample for SARS-CoV-2 testing to be able to render appropriate medical 
care for the study participant as determined by local standards of care. All findings will be 
recorded in the eCRF. 
If participants are confirmed to have SARS-CoV-2 infection, the investigator will notify the 
participant’s parent(s)/LAR(s) and the participant’s primary care physician of the diagnosis via 
fax or other Health Information Portability and Accountability Act compliant electronic data 
transfer (eg, e-mail if applicable). If the study participant does not have a primary care physician, 
the investigator will assist them to obtain one. The participant will also be instructed on infection 
prevention measures consistent with local public health guidance. Laboratory test results for 
SARS-CoV-2 infection in study participants should be submitted to state or local public health 
departments according to local policy. The investigator must either directly report to state or 
local public health department or obtain confirmation from the participant’s primary care 
physician that the positive test was reported. 
Any confirmed symptomatic SARS-CoV-2 infection that occurs in participants will be captured 
as an MAAE along with relevant concomitant medications and details about severity, 
seriousness, and outcome. Additionally, a convalescent visit may be scheduled approximately 
28 days (+7 days) after diagnosis (Section 7.3.3) if there are any doubts about the initial 
diagnosis (at the discretion of the principal investigator [PI]). At this visit a blood sample for 
potential immunologic assessment of SARS-CoV-2 infection will be collected. 
If a participant tests positive at baseline but remains asymptomatic and there are doubts about the 
validity of the positive test, Day 29 visit can be used as the convalescent visit to obtain a 
convalescent blood sample (at the discretion of the PI); the second dose may still be administered 
as long as participant remains asymptomatic and no other concerns arise. 
Once the trial is unblinded for all age groups and thus no placebo comparator group is available 
going forward, illness visits for COVID-19 symptoms or exposures and convalescent visits will 
no longer be required. COVID-19 will then be reported under regular AE reporting as per SoA. 

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7.2 Blood Collections for Immunogenicity Assessments and Biomarker 
Samples 
Blood samples for immunogenicity assessments and biomarker samples will be collected at the 
time points indicated in in the SoAs (Section 10.1). The following analytes will be measured: 
• Serum nAb titer against SARS-CoV-2 as measured by pseudovirus and/or live virus 
neutralization assays. 
• Serum bAb titer as measured by enzyme-linked immunosorbent assay specific to the 
SARS-CoV-2 S protein. 
• For Part 1, testing for serologic markers for SARS-CoV-2 infection using a nonvaccine 
antigen-based blood test at Day 1 (prior to the first dose), Day 57, Day 209, and Day 394. 
For Part 2, participants in each age group will be assigned to 5 phlebotomy cohorts. Blood 
sampling will be performed in 3 of these 5 cohorts for immunogenicity at 3 of the following time 
points: Day 1 (prior to randomization and the first dose), Day 57, and one of Day 29 (prior to the 
second dose), Day 209, and Day 394. Participants in the Cohort D (remainder of the age group) 
will provide a blood sample at Day 1 (prior to randomization and the first dose) and within 4 
days of receiving Dose 2 at Day 30 (+3 days) for storage and potential future biomarker testing 
(may include cardiac biomarkers). For participants already enrolled in Cohort D prior to 
Amendment 4, this blood draw will be optional and confirmed at time of re-consenting; for all 
participants newly enrolled into Cohort D under Amendment 4, it will be mandatory. A fifth 
cohort of participants at selected VTEU sites only, will provide blood samples for assessment of 
exploratory serology and CMI on Day 1 (prior to randomization and the first dose), Day 43, 
Day 209, and Day 394. 
All participants in Part 3 of the study will provide blood specimens for immunogenicity on Day 1 
(prior to the first dose) and will also provide additional samples at Day 57, Day 149/BD-Day 1, 
one month after the third dose on Day 177/ BD-Day 29. The first 150 participants 
(Sub-Cohort F) will also have a blood draw on Day 329/BD-Day 181; the second 
150 participants (Sub-Cohort G) will also have a blood draw on Day 514/BD-Day 366. 
All participants in Part 1 and Part 2 who choose to receive a booster dose will provide a blood 
specimen for immunogenicity and serostatus on BD-Day 1; a subgroup of participants will also 
provide one additional blood specimen for immunogenicity. Please see Table 16 for details. 
Sample aliquots will be designed to have backup samples, if possible; vial volumes will likely be 
adequate for future testing needs. The actual time and date of each sample collected will be 
recorded in the eCRF, and unique sample identification will be utilized to maintain the blind at 
the laboratory at all times and to allow for automated sample tracking and housing. Handling and 

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preparation of the samples for analysis, as well as shipping and storage requirements, will be 
provided in a separate study laboratory manual. 
Measurement of bAb and nAb levels will be performed in a laboratory designated by the 
Sponsor. 
According to the ICF section (Section 10.2.6), serum from immunogenicity testing may be used 
for future research, which may be performed at the discretion of the Sponsor to further 
characterize the immune response to SARS-CoV-2, additional assay development, and the 
immune response across CoVs. 
The planned volume of blood to be sampled per participant in Part 1, Part 2, and Part 3 (serology 
cohorts) for each age group for immunogenicity assessments in 1 day is as follows: 
• 6 months to < 2 years: approximately 8 mL 
• 2 years to < 6 years: approximately 16 mL 
• 6 years to < 12 years: approximately 24 mL 
The planned volume of blood to be sampled per participant at the Day 30 (+3 days) blood draw 
for storage and potential future biomarker testing for Cohort D in Part 2 is as follows: 
• All ages: approximately 4 mL 
The planned volume of blood to be sampled per participant in the exploratory serology and CMI 
cohort for each age group in 1 day is as follows: 
• 6 months to < 2 years: approximately 9 mL 
• 2 years to < 6 years: approximately 9 mL 
• 6 years to < 12 years: approximately 17 mL 
Note: If less than 8 mL of blood is obtained for any given child at baseline, except for Cohort D 
for 6 months to < 2 years, where 4 mL can be obtained, the child cannot be enrolled. 
Blood volumes for Booster phase: 
• BD-Day 1 (pre-booster) and post-booster draw for 2 year to < 12-year-old children (at 
time of booster): approximately 8 mL. 
• BD-Day 1 (pre-booster) and post-booster draw for 6 months to < 2 year-old children (at 
time of booster): approximately 4 mL. 
 
 

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7.3 Inferred Efficacy Assessments 
7.3.1 Vaccine Effectiveness Assessments 
Vaccine effectiveness for children 6 months to < 12 years of age will be inferred based on serum 
antibody responses obtained on Day 57 (28 days after the second injection of mRNA-1273). 
Inference will be based on assessing the antibody responses against the following: 
1.  If available at the time of analysis, antibody responses will be assessed against an 
accepted serum antibody threshold conferring protection against COVID-19. 
2.  If an accepted threshold of protection is not available, noninferiority of the GM value of 
serum antibody and SRR of children 6 months to < 12 years of age (Study P204) 
compared with the GM value of serum antibody and SRR from young adults (18 to 
25 years of age) enrolled in the ongoing clinical endpoint efficacy trial (Study P301) will 
be assessed. The statistical parameters to infer effectiveness are described in Section 8. 
COVID-19: 
To be considered as a case of COVID-19 for the evaluation of the efficacy endpoint, the 
following case definition must be met: 
• The participant must have at least 1 nasal swab (or respiratory sample, if hospitalized) 
positive for SARS-CoV-2 by RT-PCR AND 
• ONE of the following: 
− Fever (temperature ≥ 38ºC/≥ 100.4ºF) or chills (of any duration, including ≤ 4 hours) 
− Shortness of breath or difficulty breathing (of any duration, including ≤ 48 hours) 
− Cough (of any duration, including ≤ 48 hours) 
− Fatigue 
− Muscle or body aches 
− Headache 
− New loss of taste or smell 
− Sore throat 
− Congestion or runny nose 
− Abdominal pain 
− Nausea or vomiting 
− Diarrhea 

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− Poor appetite/poor feeding 
Severe COVID-19: 
To be considered severe COVID-19, the following criteria must be met: 
• Confirmed COVID-19 as per the COVID-19 case definition, plus any of the following: 
− Meeting criteria for systemic inflammatory response syndrome based on age -specific 
variables (Table 6) OR 
− Respiratory failure or acute respiratory distress syndrome (defined as needing 
high-flow oxygen, noninvasive or mechanical ventilation, or extracorporeal 
membrane oxygenation), medical intervention for shock (intravenous fluids, 
vasopressors, etc), OR 
− Significant acute renal, hepatic, or neurologic dysfunction (Table 7), OR 
− Admission to an ICU or death. 
Table 6: Age-Specific Cut-Offs for Vital Signs and Laboratory Variables 
Age Group 
Heart Rate, 
Beats/Min 
Respiratory 
Rate, 
Breaths/Min 
Leukocyte 
Count, 
Leukocytes × 
103/mm3 
Systolic 
Blood 
Pressure, 
mm Hg 
Tachycardia Bradycardia 
1 month to 1 year 
> 180 
< 90 
> 34 
> 17.5 or < 5 
< 70  
2 years to 5 years 
> 140 
NA 
> 22 
> 15.5 or < 6 
< 70 + (age 
in years x 2)  
6 years to 10 years 
> 130 
NA 
> 18 
> 13.5 or < 4.5 
< 70 + (age 
in years x 2) 
>10 years 
> 130 
NA 
>18 
> 13.5 or < 4.5 
< 90  
Abbreviations: AHA = American Heart Association; NA = not applicable. 
Note: Lower values for heart rate, leukocyte count, are for the 5th percentile and upper values for heart rate, 
respiratory rate, or leukocyte count are for the 95th percentile for that age group. Systolic blood pressure values are 
based on AHA definitions of hypotensive shock for pediatric population. 
Source: Goldstein et al 2005 and Topjian et al 2020. 

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Table 7: Definition of Renal-, Liver- and Neurological Dysfunction for Pediatric 
Population (< 12 years of age) 
Acute Renal 
Dysfunction  
• 
Increase in serum creatinine by ≥ 0.3 mg/dL (≥26.5 µmol/L) within 48 hours; 
OR 
• 
Increase in serum creatinine to ≥ 1.5 times baseline, known or presumed to 
have occurred within prior 7 days 
OR 
• 
Urine volume ≤ 0.5 mL/ kg/ hour for 6 hours 
Acute Liver 
Dysfunction 
• 
> 3-fold elevation above the upper normal limit for ALT or AST 
OR 
• 
> 2-fold elevation above the upper normal limit for total serum bilirubin or 
GGT or ALP 
Acute 
Neurological 
Dysfunctiona 
ANY of the following: 
• 
Loss of sense of smell or taste 
• 
Seizures or status epilepticus 
• 
Severe headache (preventing normal daily activities) 
• 
Persistent difficulty walking or crawling (if crawling/walking before) 
• 
Persistent altered awareness or confusion (preventing normal daily activities) 
• 
Persistent severe fatigue or weakness (preventing normal daily activities) 
Abbreviations: ALT = alanine aminotransferase; ALP = alkaline phosphatase; AST = aspartate aminotransferase; 
GGT = gamma-glutamyl transferase. 
Source: aLaRovere et al 2021. 
Death attributed to COVID-19 is defined as any participant who dies during the study with a 
cause directly attributed to a complication of COVID-19. 
SARS-CoV-2 Infection: 
• SARS-CoV-2 infection is defined in participants with SARS-CoV-2 negative at Baseline: 
− bAb level against SARS-CoV-2 nucleocapsid protein negative at Day 1 that becomes 
positive (as measured by Roche Elecsys) post Baseline, OR 
−  Positive RT-PCR post Baseline 
7.3.2 Surveillance for COVID-19 Symptoms 
While Part 2 is still blinded for any age group, COVID-19 surveillance will be conducted for all 
participants enrolled in the study. 

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Once the trial is unblinded for all age groups and thus no placebo comparator group is available 
going forward, COVID-19 surveillance will be discontinued, and COVID-19 cases will be 
reported under standard AE reporting per SoA only. 
While Part 2 is still blinded for any age group, surveillance for COVID-19 symptoms will be 
conducted via biweekly telephone calls or eDiary prompts as specified in Section 7.1.1 and 
Figure 2; starting after participant enrollment and continuing throughout the study. 
If there is no response to an eDiary prompt for 2 days, the study site staff will contact the study 
participant by telephone. 
According to the CDC, as of 22 Dec 2020 (CDC 2020c), patients with COVID-19 have reported 
a wide range of symptoms ranging from mild symptoms to severe illness. Throughout the study 
while Part 2 for any age group is still blinded, to survey for COVID-19, the following pre-
specified symptoms that meet the criteria for suspicion of COVID-19 will be elicited weekly 
from the participant, and the presence of any one of these symptoms (in the absence of an 
alternative diagnosis) lasting at least 48 hours (except for fever and/or respiratory symptoms) 
will result in the study site staff arranging an illness visit to collect a nasal swab for SARS-CoV-
2 within 72 hours. 
• Fever (temperature ≥ 38ºC/≥ 100.4ºF) or chills (of any duration, including ≤ 48 hours) 
• Shortness of breath or difficulty breathing (of any duration, including ≤ 48 hours) 
• Cough (of any duration, including ≤ 48 hours) 
• Fatigue 
• Muscle or body aches 
• Headache 
• New loss of taste or smell 
• Sore throat 
• Congestion or runny nose 
• Abdominal pain 
• Nausea or vomiting 
• Diarrhea 
• Poor appetite/poor feeding 

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Figure 2: 
Surveillance for COVID-19 Symptoms and the Corresponding Clinical Data 
Pathways 
 
Abbreviations: COVID-19 = coronavirus disease 2019, HCP = healthcare practitioner, RT-PCR = reverse 
transcriptase polymerase chain reaction, SARS-CoV-2 = severe acute respiratory syndrome coronavirus 2. 
It is important to note that some of the symptoms of COVID-19 overlap with solicited systemic 
ARs that are expected after vaccination with mRNA-1273 (eg, myalgia, headache, fever, and 
chills). During the first 7 days after vaccination, when these solicited ARs are common, 
investigators should use their clinical judgment to decide if a nasal swab should be collected. The 
collection of a nasal swab prior to the first dose on Day 1, prior to the second dose on Day 29, 
and then at all subsequent study visits (Day 43 [if visit is applicable], Day 57, Day 209, and 
Day 394) can help ensure that cases of COVID-19 are not overlooked. If the participant decides 
to receive the optional booster dose, nasal swabs should be collected as described in Table 15. 

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Any study participant who reports respiratory symptoms during the 7-day period after 
vaccination without an alternative diagnosis should be evaluated for COVID-19. 
For children with febrile illnesses, if an alternative diagnosis is identified (eg, positive urine 
culture, streptococcal pharyngitis, cellulitis), the investigator may decide to omit the illness visit. 
Identification of an alternative viral agent (such as respiratory syncytial virus or influenza by 
rapid testing) does not satisfy this requirement, as co-infections with SARS-CoV-2 may occur. 
An investigator may elect to omit the illness visit if standard of care testing prior to the illness 
visit reveals a negative COVID-19 nucleic acid amplification test performed at a Clinical 
Laboratory Improvement Amendments (CLIA)-certified or CLIA-waived laboratory and the 
principal investigator can obtain a copy of the negative test. Home testing kits cannot be used to 
satisfy this testing requirement. Standard of care evaluation of household contacts that reveals a 
negative COVID-19 is not sufficient to omit an illness visit in the study participant. 
During the course of the study when Part 2 for any age group is still blinded participants with 
symptoms of COVID-19 will be asked to return within 72 hours or as soon as possible to the 
study site or trained staff from the study site will conduct a home visit as soon as possible to 
collect a nasal swab sample (for RT-PCR) for evaluation of COVID-19. Both study site visits 
and home visits are referred to as illness visits (Section 7.1.5). Additionally, a convalescent visit 
may be scheduled approximately 28 days (+7 days) after diagnosis (Section 7.3.3) if there are 
any doubts about the initial diagnosis (at the discretion of the investigator). At this visit, a blood 
sample will be collected for potential immunologic assessment of SARS-CoV-2 infection. 
Once the trial is unblinded for all age groups and thus no placebo comparator group is available 
going forward, illness visits for COVID-19 symptoms or exposures and convalescent visits will 
no longer be required. 
Cases are defined as participants meeting clinical criteria based both on symptoms for 
COVID-19 and on RT-PCR detection of SARS-CoV-2 from samples collected within 72 hours 
of the study participant reporting symptoms meeting the definition of COVID-19. Participants 
who are hospitalized for COVID-19 without the opportunity for a clinic or home visit will also 
be considered cases, assuming that the symptomology criteria for COVID-19 are met and a 
respiratory sample is positive for SARS-CoV-2 by RT-PCR at a certified laboratory. 
Investigators are encouraged to try to obtain a respiratory sample during the course of 
hospitalization or immediately after hospital discharge as an unscheduled visit for submission to 
the study central laboratory, if feasible. The investigator should determine if the criteria for 
severe COVID-19 have been met. 
Severe COVID-19 is defined in Section 7.3.1. 

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All clinical findings will be recorded in the eCRF. While COVID-19 surveillance is ongoing, all 
confirmed cases of symptomatic COVID-19 will be captured as MAAEs, along with relevant 
concomitant medications and details about severity, seriousness, and outcome, and will be 
reported immediately to the Sponsor or designee (Section 7.4.4). Once COVID-19 surveillance is 
discontinued, COVID-19 cases will be reported as per standard AE reporting (only if medically 
attended, SAEs or leading to discontinuation from study or vaccination). 
7.3.3 Follow-up/Convalescent Period After Diagnosis with COVID-19 
Any confirmed symptomatic COVID-19 occurring in a participant will be captured as an MAAE 
along with relevant concomitant medications and details about severity, seriousness, and 
outcome. Additionally, a convalescent visit may be scheduled approximately 28 days (+ 7 days) 
after diagnosis if there are any doubts about the initial diagnosis (at the discretion of the PI). At 
this visit, a blood sample for potential immunologic assessment of SARS-CoV-2 infection will 
be collected (see the SoAs [Section 10.1]). The investigator should determine if the criteria for 
severe COVID-19 have been met. If the participant is hospitalized, study site personnel will try 
to obtain medical records and SARS-CoV-2 diagnostic results. If the participant is later 
discharged from the hospital during the 28-day period following diagnosis of COVID-19, the 
study site personnel will arrange for a resumption of the protocol schedule. 
Children hospitalized with possible or confirmed MIS-C may also have the same convalescent 
visit scheduled approximately 28 days (+7 days) after onset of hospitalization at the 
Investigator’s discretion. At this visit, a blood sample for potential immunologic assessment of 
SARS-CoV-2 infection will be collected (see the SoAs [Section 10.1]). 
Once the trial is unblinded for all age groups and thus no placebo comparator group is available 
going forward, convalescent visits will no longer be required. 
7.4 Safety Definitions and Related Procedures 
7.4.1 Adverse Event 
An AE is defined as any untoward medical occurrence associated with the use of a drug in 
humans, whether or not considered drug related. 
Events Meeting the Adverse Event Definition 
• Exacerbation of a chronic or intermittent pre-existing condition including either an 
increase in frequency and/or intensity of the condition. 
• New conditions detected or diagnosed after the first dose of IP even though they may 
have been present before the start of the study. 

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Events NOT Meeting the Adverse Event Definition 
• Medical or surgical procedure (eg, endoscopy, appendectomy): the condition that leads to 
the procedure should be the AE. 
• Situations in which an untoward medical occurrence did not occur (social and/or 
convenience admission to a hospital). 
• Planned procedures (eg, tonsillectomy or pressure-equalization tubes) that occur during 
the study period but were planned prior to enrollment will not be considered AE unless 
complications arise. 
An AR is any AE for which there is a reasonable possibility that the vaccine caused the AE 
(Section 7.4.9). For the purposes of IND safety reporting, “reasonable possibility” means that 
there is evidence to suggest a causal relationship between the vaccine and the AE. 
An unsolicited AE is any AE reported by the participant that is not specified as a solicited AR in 
the protocol or is specified as a solicited AR but starts outside the protocol-defined period for 
reporting solicited ARs (ie, the day of each dose of injection and the 6 days after the day of 
dosing). 
7.4.2 Serious Adverse Events 
An AE (including an AR) is considered an SAE if, in the view of either the investigator or 
Sponsor, it results in any of the following outcomes: 
• Death 
A death that occurs during the study or that comes to the attention of the investigator 
during the protocol-defined follow-up period must be reported to the Sponsor, whether or 
not it is considered related to the IP. 
• Is life-threatening  
An AE is considered life-threatening if, in the view of either the investigator or the 
Sponsor, its occurrence places the participant at immediate risk of death. It does not 
include an AE that, had it occurred in a more severe form, might have caused death. 
• Inpatient hospitalization or prolongation of existing hospitalization 
In general, inpatient hospitalization indicates the participant was admitted to the hospital 
or emergency ward for at least one overnight stay for treatment that would not have been 
appropriate in the physician’s office or outpatient setting. The hospital or emergency 
ward admission should be considered an SAE regardless of whether opinions differ as to 
the necessity of the admission. Complications that occur during inpatient hospitalization 
will be recorded as AEs; however, if a complication/AE prolongs hospitalization or 

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otherwise fulfills SAE criteria, the complication/AE will be recorded as a separate SAE. 
Note: 24-hour observation admissions, typically used to extend the period of observation 
from an emergency department or urgent care visit, will not be considered inpatient 
hospitalization unless they are converted to hospital admission after the 24 hours of 
observation have expired. 
• Persistent or significant incapacity or substantial disruption of the ability to conduct 
normal life functions 
This definition is not intended to include experiences of relatively minor medical 
significance such as uncomplicated headache, nausea/vomiting, diarrhea, influenza, and 
accidental trauma (eg, sprained ankle) that may interfere with or prevent everyday life 
functions but do not constitute a substantial disruption. 
• Congenital anomaly or birth defect 
• Medically important event  
Medical judgment should be exercised in deciding whether SAE reporting is appropriate 
in other situations, such as important medical events that may not be immediately 
life-threatening or result in death or hospitalization but that jeopardize the participant or 
require medical or surgical intervention to prevent one of the other outcomes listed in the 
above definition. These events should usually be considered serious. Examples of such 
medical events include allergic bronchospasm requiring intensive treatment in an 
emergency room or at home, blood dyscrasias or convulsions that do not result in 
inpatient hospitalization, or the development of drug dependency or drug abuse. 
7.4.3 Solicited Adverse Reactions 
The term “reactogenicity” refers to the occurrence and intensity of selected signs and symptoms 
(ARs) that occur after IP injection. The eDiary will solicit daily participant reporting of ARs 
using a structured checklist (Section 7.1.1). Participant’s parent(s)/LAR(s) will record such 
occurrences in an eDiary on the day of each dose of injection and for the 6 days after the day of 
dosing. 
Severity grading of reactogenicity will occur automatically based on participant entry into the 
eDiary according to the grading scales presented in Table 8 and Table 9, modified from the 
Toxicity Grading Scale for Healthy Adult and Adolescent Volunteers Enrolled in Preventative 
Vaccine Clinical Trials (DHHS 2007). 
If a solicited local or systemic AR continues beyond Day 7 after vaccination, the participant’s 
parent(s)/LAR(s) will be prompted to capture details of the solicited local or systemic AR in the 
eDiary until it resolves or the next IP injection occurs, whichever occurs first. Capture of details 
of ARs in the eDiary should not exceed 28 days after each vaccination. Adverse reactions 

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recorded in the eDiary beyond Day 7 should be reviewed by the study site staff either during the 
next scheduled telephone call or at the next study site visit. All solicited ARs (local and 
systemic) will be considered related to the IP. 
After booster doses with mRNA-1273.214, local or systemic ARs will only be reported if they 
are medically attended, considered serious or lead to discontinuation from the study. No eDiaries 
will be used after booster doses with mRNA-1273.214. 
Table 8: 
Solicited Adverse Reactions and Grades: Age 37 Months to < 12 years1 
Reaction 
Grade 0 
Grade 1 
Grade 2 
Grade 3 
Grade 42 
Injection site pain 
None 
Does not 
interfere with 
activity 
Interferes with 
activity 
Prevents daily 
activity 
Requires emergency 
room visit3 or 
hospitalization 
Injection site 
erythema (redness) 
< 25 mm/ 
 < 2.5 cm 
25-50 mm/ 
2.5-5 cm 
51-100 mm/ 
5.1-10 cm 
> 100 mm/ 
> 10 cm 
Necrosis or 
exfoliative 
dermatitis 
Injection site 
swelling/induration 
(hardness) 
< 25 mm/ 
< 2.5 cm 
25-50 mm/ 
2.5-5 cm 
51-100 mm/ 
5.1-10 cm 
> 100 mm/ 
> 10 cm 
Necrosis 
Axillary 
(underarm) 
swelling or 
tenderness 
ipsilateral to the 
side of injection 
None 
No 
interference 
with activity 
Some 
interference 
with activity 
Prevents daily 
activity 
Emergency room 
visit3 or 
hospitalization 
Headache 
None 
No 
interference 
with activity 
Some 
interference 
with activity 
Significant; 
Prevents daily 
activity 
Requires emergency 
room visit3 or 
hospitalization 
Fatigue 
None 
No 
interference 
with activity 
Some 
interference 
with activity 
Significant; 
prevents daily 
activity 
Requires emergency 
room visit3 or 
hospitalization 
Myalgia (muscle 
aches all over 
body) 
None 
No 
interference 
with activity 
Some 
interference 
with activity 
Significant; 
prevents daily 
activity 
Requires emergency 
room visit3 or 
hospitalization 
Arthralgia (joint 
aches in several 
joints) 
None 
No 
interference 
with activity 
Some 
interference 
with activity 
Significant; 
prevents daily 
activity 
Requires emergency 
room visit3 or 
hospitalization 
Nausea/vomiting 
None 
No 
interference 
Some 
interference 
Prevents daily 
activity, 
Requires emergency 
room visit3 or 

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Reaction 
Grade 0 
Grade 1 
Grade 2 
Grade 3 
Grade 42 
with activity 
or 1-2 
episodes/ 
24 hours 
with activity 
or 
> 2 episodes/ 
24 hours 
hospitalization for 
hypotensive shock 
Chills 
None 
No 
interference 
with activity 
Some 
interference 
with activity 
not requiring 
medical 
intervention 
Prevents daily 
activity and 
requires 
medical 
intervention 
Requires emergency 
room visit3 or 
hospitalization 
Fever 
< 38.0°C 
< 100.4°
F 
38.0-38.4°C 
100.4-101.1°F 
38.5-38.9°C 
101.2-102.0°F 
39.0-40.0°C 
102.1-104.0°F 
> 40.0°C 
> 104.0°F 
1 Age at time of enrollment determines the scale to be used. 
2 Grading for Grade 4 events per investigator assessment (with exception of fever). 
3 Emergency room visit includes urgent care visit. 
Source: Guidance for industry – Toxicity Grading Scale for Healthy Adult and Adolescent Volunteers Enrolled in 
Preventative Vaccine Clinical Trials (DHHS 2007). 
Table 9: Solicited Adverse Reactions and Grades: Age 6 Months to ≤ 36 Months1 
Reaction 
Grade 0 
Grade 1 
Grade 2 
Grade 3 
Grade 42 
Local Reaction 
Injection site 
pain/tenderness 
None 
Mild discomfort 
to touch or 
some pain but 
no interference 
with normal 
daily activities 
Cries when limb 
is moved/refuses 
to move limb or 
pain interferes 
with normal 
daily activities 
Significant pain 
at rest or pain 
prevents normal 
daily activities 
Requires 
emergency 
room visit3 or 
hospitalization 
Injection site 
erythema (redness) 
< 5 mm/ 
< 0.5 cm 
5-20 mm/ 
0.5-2.0 cm 
> 20-50 mm 
> 2.0-5.0 cm 
> 50 mm/ 
> 5 cm 
Necrosis or 
exfoliative 
dermatitis 
Injection site 
swelling/induration 
(hardness) 
< 5 mm/ 
< 0.5 cm 
5-20 mm/ 
0.5-2.0 cm 
> 20-50 mm 
> 2.0-5.0 cm 
> 50 mm/ 
> 5 cm 
Necrosis 

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Reaction 
Grade 0 
Grade 1 
Grade 2 
Grade 3 
Grade 42 
Groin or underarm 
swelling or 
tenderness 
ipsilateral to the 
side of injection 
None 
Some swelling 
or tenderness 
but no 
interference 
with normal 
daily activities 
Swelling or 
tenderness that 
interferes with 
normal daily 
activities 
Swelling or 
tenderness that 
prevents normal 
daily activities 
Emergency 
room visit3 or 
hospitalization 
Systemic Reaction 
Fever 
< 38.0°C 
38.0-38.4°C 
100.4-101.1°F 
38.5-39.5°C 
101.2-103.1°F 
39.6-40.0°C 
103.2-104.0°F 
> 40.0°C 
> 104.0°F  
Irritability/crying 
None 
Lasting < 1 
hour or easily 
consolable 
Lasting 1-3 hours 
or requiring 
increased 
attention 
Lasting > 3 
hours or 
inconsolable 
Requires 
emergency 
room visit3 or 
hospitalization 
Sleepiness 
None 
Sleepier than 
usual or less 
interested in 
surroundings 
Not interested in 
surroundings or 
sleeps through 
meals 
Sleeps most of 
the time, hard 
to arouse 
 
Inability to 
arouse 
Loss of appetite 
 
 
None 
Eating less than 
normal for 1-2 
feeds/meals 
Missed 1-2 
feeds/ meals 
completely 
Missed 
> 2 feeds/meals 
completely or 
refuses most 
feeds/meals 
Requires 
emergency 
room visit3 or 
hospitalization 
1 Age at time of enrollment determines the scale to be used. 
2 Grading for Grade 4 events per investigator assessment (with exception of fever). 
3 Emergency room visit includes urgent care visit. 
Source: Guidance for industry – Toxicity Grading Scale for Healthy Adult and Adolescent Volunteers Enrolled in 
Preventative Vaccine Clinical Trials (DHHS 2007). 
Any solicited AR that meets any of the following criteria must be entered into the participant’s 
source document and must also be recorded by the study site staff on the solicited AR page of the 
participant’s eCRF: 
• Solicited local or systemic AR that results in a visit to a healthcare practitioner (HCP; 
otherwise meets the definition of an MAAE) 
• Solicited local or systemic AR leading to the participant withdrawing from the study or 
the participant being withdrawn from the study by the investigator (AE leading to 
withdrawal) 
• Solicited local or systemic AR lasting beyond 7 days after injection 
• Solicited local or systemic AR that leads to participant withdrawal from IP 

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• Solicited local or systemic AR that otherwise meets the definition of an SAE 
7.4.4 Medically Attended Adverse Events 
An MAAE is an AE that leads to an unscheduled visit to an HCP. This would include visits to a 
study site for unscheduled assessments (eg, abnormal laboratory test result follow-up, 
COVID-19 [Section 7.3.1]) and visits to HCPs external to the study site (eg, urgent care, primary 
care physician). Investigators will review unsolicited AEs for the occurrence of any MAAE. 
Unsolicited AEs will be captured on the AE page of the eCRF. 
While COVID-19 surveillance is ongoing, all confirmed symptomatic COVID-19 cases 
(Section 7.3.1) will be recorded as MAAEs. Any severe COVID-19 cases will be reported to the 
Sponsor or designee immediately and in all circumstances within 24 hours, using the SAE 
Mailbox, the SAE Hotline, or the SAE Fax line (Section 7.4.11). The investigator will submit 
any updated COVID-19 case data to the Sponsor within 24 hours of it being available. 
Once COVID-19 surveillance is discontinued, COVID-19 related AEs will be reported per 
standard AE reporting for the respective SoA. 
All suspected cases of anaphylaxis should be recorded as MAAEs and reported as an SAE, based 
on criteria for a medically important event, unless the event meets other serious criteria. As an 
SAE, the event should be reported to the Sponsor or designee immediately and in all 
circumstances within 24 hours as per Section 7.4.11. The investigator will submit any updated 
anaphylaxis case data to the Sponsor within 24 hours of it being available. For reporting 
purposes, a participant who displays signs/symptoms consistent with anaphylaxis as described 
below should be reported as a potential case of anaphylaxis. This is provided as general guidance 
for investigators and is based on the Brighton Collaboration case definition (Rüggeberg et al 
2007). 
Anaphylaxis is an acute hypersensitivity reaction with multi-organ-system involvement that can 
present as, or rapidly progress to, a severe life-threatening reaction. It may occur following 
exposure to allergens from a variety of sources. 
Anaphylaxis is a clinical syndrome characterized by: 
Sudden onset AND 
Rapid progression of signs and symptoms AND 
Involves 2 or more organ systems, as follows: 
− Skin/mucosal: urticaria (hives), generalized erythema, angioedema, generalized 
pruritus with skin rash, generalized prickle sensation, red and itchy eyes 

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− Cardiovascular: measured hypotension, clinical diagnosis of uncompensated shock, 
loss of consciousness or decreased level of consciousness, evidence of reduced 
peripheral circulation 
− Respiratory: bilateral wheeze (bronchospasm), difficulty breathing, stridor, upper 
airway swelling (lip, tongue, throat, uvula, or larynx), respiratory distress, persistent 
dry cough, hoarse voice, sensation of throat closure, sneezing, rhinorrhea 
− Gastrointestinal: diarrhea, abdominal pain, nausea, vomiting 
7.4.5 Adverse Events of Special Interest 
An AESI is an AE (serious or nonserious) of scientific and medical concern specific to the 
Sponsor’s product or program for which ongoing monitoring and immediate notification by the 
investigator to the Sponsor is required and documentation in the form of a case narrative. Such 
events may require further investigation to characterize and understand them. Refer to 
Section 10.4, Appendix 4 for a list of AESIs pertinent to this study. All AESIs will be collected 
through the entire study period and must be reported to the Sponsor or designee immediately and 
in all circumstances within 24 hours of becoming aware of the event via the EDC system. If a 
site receives a report of a new AESI from a study participant or receives updated data on a 
previously reported AESI and the eCRF has been taken offline, then the site can report this 
information on a paper AESI form using the SAE Mailbox, the SAE Hotline, or the SAE Fax 
line (Section 7.4.11). 
Acute Myocarditis and/or Pericarditis 
All suspected cases of probable and confirmed myocarditis, pericarditis, or myopericarditis 
should be recorded as an AESI and reported as an SAE, if the event meets seriousness criteria. 
As an SAE, the event should be reported to the Sponsor or designee immediately and in all 
circumstances within 24 hours as per Section 7.4.11. The investigator will submit any updated 
myocarditis, pericarditis or myopericarditis case data to the Sponsor within 24 hours of it being 
available. For reporting purposes, a participant who displays signs/symptoms consistent with the 
CDC case definition as described below (Gargano et al, 2021), should be reported as a potential 
case of confirmed or probable myocarditis, pericarditis, or myopericarditis. 
Acute Myocarditis Case Definition 
Presence of ≥ 1 new or worsening of the following clinical symptoms (persons who lack the 
listed symptoms but who meet other criteria may be classified as subclinical myocarditis 
[probable or confirmed]): 
• Chest pain/pressure/discomfort 

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• Dyspnea/shortness of breath/pain with breathing 
• Palpitations 
• Syncope 
OR 
Infants and children aged < 12 years might instead have ≥ 2 of the following symptoms: 
• Irritability 
• Vomiting 
• Poor feeding 
• Tachypnea 
• Lethargy 
AND 
For PROBABLE CASE: 
Presence of ≥ 1 new finding of the following: 
• Troponin level above upper limit of normal (any type of troponin) 
• Abnormal electrocardiogram (ECG or EKG) or rhythm monitoring findings consistent 
with myocarditis 
o To meet the ECG or rhythm monitoring criterion, a probable case must include at 
least one of the following: 
▪ ST segment or T-wave abnormalities 
▪ Paroxysmal or sustained atrial, supraventricular, or ventricular 
arrhythmias 
▪ AV nodal conduction delays or intraventricular conduction defects 
• Abnormal cardiac function or wall motion abnormalities on echocardiogram 
• cMRI finding consistent with myocarditis (Ferreira et al, 2018) 
AND 
• No other identifiable cause of the symptoms and findings 
For CONFIRMED CASE: 
• Histopathologic confirmation of myocarditis (using Dallas criteria [Aretz, 1987]) 

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OR 
• cMRI findings consistent with myocarditis in the presence of troponin level above upper 
limit of normal (any type of troponin) 
AND 
• No other identifiable cause of the symptoms and findings 
Acute Pericarditis Case Definition 
Presence of  ≥ 2 new or worsening of the following clinical features (Adler, et al 2015): 
• Acute chest pain (Typically described as pain made worse by lying down, deep 
inspiration, or cough; and relieved by sitting up or leaning forward, although other types 
of chest pain may occur) 
• Pericardial rub on examination 
• New ST-elevation or PR-depression on EKG 
• New or worsening pericardial effusion on echocardiogram or MRI 
Myopericarditis Case Definition 
Participants who meet criteria for both myocarditis and pericarditis may be described under 
myopericarditis. 
An independent Cardiac Event Adjudication Committee (CEAC) consisting of pediatric and 
adult cardiologists will review suspected cases of myocarditis, pericarditis, or myopericarditis to 
determine if they meet CDC criteria of “probable” or “confirmed” event, and to assess severity 
and enable the DSMB to make recommendations to the Sponsor to continue vaccine dosing. The 
CEAC will operate under the rules of an approved charter that will be written and reviewed at 
the organizational meeting of the CEAC. Details regarding the CEAC composition, 
responsibilities, procedures, and frequency of data review will be defined in its charter. 
MIS-C Case Definition 
Investigators will also be asked to report, as an AESI, clinical signs/symptoms consistent with 
the CDC case definition of MIS-C (CDC 2020d): 
• An individual aged < 21 years presenting with fever, laboratory evidence of 
inflammation, and evidence of clinically severe illness requiring hospitalization, with 
multisystem (> 2) organ involvement (cardiac, renal, respiratory, hematologic, 
gastrointestinal, dermatologic, or neurological) 
AND 

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• No alternative plausible diagnoses 
WITH OR WITHOUT 
• Positive for current or recent SARS-CoV-2 infection by RT-PCR, serology 
(non-S protein-based), or antigen test or COVID-19 exposure within the 4 weeks prior to 
the onset of symptoms: 
o Fever ≥ 38.0°C/≥ 100.4ºF for ≥ 24 hours, or report of subjective fever lasting 
≥ 24 hours 
o Including, but not limited to, one or more of the following: an elevated C-reactive 
protein, erythrocyte sedimentation rate, fibrinogen, procalcitonin, d-dimer, 
ferritin, lactic acid dehydrogenase, or interleukin 6; elevated neutrophils; reduced 
lymphocytes; or low albumin 
Some participants may fulfill full or partial criteria for Kawasaki disease but it should be 
reported if they meet the case definition for MIS-C. Consider MIS-C in any pediatric death with 
evidence of SARS-CoV-2 infection. 
7.4.6 Recording and Follow-up of Pregnancy 
Female participants who have a positive pregnancy test at Screening should not be enrolled; 
participants who have a positive pregnancy test any time during the study should receive no 
further dosing with IP but should be asked to remain in the study and be monitored for safety. 
Details of all pregnancies in female participants will be collected after the start of study 
treatment and until the end of their participation in the study. 
• If a pregnancy is reported, the investigator should inform the Sponsor within 24 hours of 
learning of the pregnancy and should follow the procedures outlined in this section. 
• Abnormal pregnancy outcomes (eg, spontaneous abortion, fetal death, stillbirth, 
congenital anomalies, ectopic pregnancy) are considered SAEs. 
Pregnancies occurring in participants after enrollment must be reported to the Sponsor or 
designee within 24 hours of the study site learning of its occurrence, using the SAE Mailbox, the 
SAE Hotline, or the SAE Fax line (Section 7.4.11). If the participant agrees to submit this 
information, the pregnancy must be followed to determine the outcome, including spontaneous 
or voluntary termination, details of the birth, and the presence or absence of any birth defects, 
congenital abnormalities, or maternal and/or newborn complications. This follow-up should 
occur even if the intended duration of the safety follow-up for the study has ended. Pregnancy 
report forms will be distributed to the study site to be used for this purpose. The investigator 

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must immediately (within 24 hours of awareness) report to the Sponsor any pregnancy resulting 
in an abnormal outcome according to the procedures described for SAEs. 
7.4.7 Eliciting and Documenting Adverse Events 
The investigator is responsible for ensuring that all AEs and SAEs are recorded in the eCRF and 
reported to the Sponsor. 
Solicited ARs will be collected from Day 1 through 7 days after each dose (ie, the day of 
injection and 6 subsequent days). Other (unsolicited) AEs will be collected from Day 1 through 
28 days after each dose. 
Both MAAEs and SAEs will be collected from participants as specified in the SoAs 
(Section 10.1) until the end of their participation in the study. Any AEs that occur before 
administration of IP will be analyzed separately from AEs that occur after vaccine 
administration. 
At every study site visit or telephone contact, participants or parent(s)/LAR(s) will be asked a 
standard question to elicit any medically related changes in the participant’s well-being 
(including COVID-19 symptoms). Participants or parent(s)/LAR(s) will also be asked if the 
participant has been hospitalized, had any accidents, used any new medications, changed 
concomitant medication regimens (both prescription and over-the-counter medications), or had 
any nonstudy vaccinations. 
In addition to participant observations, physical examination findings or data relevant to 
participant safety classified as an AE will be documented on the AE page of the eCRF. 
After the initial AE/SAE report, the investigator is required to proactively follow each participant 
at subsequent visits/contacts. All AEs and SAEs will be treated as medically appropriate and 
followed until resolution, stabilization, the event is otherwise explained, or the participant is 
LTFU (as defined in Section 6.5). 
7.4.8 Assessment of Intensity 
An event is defined as “serious” when it meets at least one of the predefined outcomes as 
described in the definition of an SAE (Section 7.4.2), NOT when it is rated as severe. 
The severity (or intensity) of an AR or AE refers to the extent to which it affects the participant’s 
daily activities. The Toxicity Grading Scale for Healthy Adult and Adolescent Volunteers 
Enrolled in Preventative Vaccine Clinical Trials (DHHS 2007), modified for use in children 
37 months to < 12 years of age (Table 8) and 6 months to ≤ 36 months of age (Table 9), will be 
used to categorize local and systemic reactogenicity events (solicited ARs) and body temperature 

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measurements observed during this study. Specific criteria for local and systemic reactogenicity 
events are presented in Section 7.4.3. 
The determination of severity for all unsolicited AEs should be made by the investigator based 
upon medical judgment and the definitions of severity, as follows: 
• Mild: These events do not interfere with the participant’s daily activities. 
• Moderate: These events cause some interference with the participant’s daily activities and 
require limited or no medical intervention. 
• Severe: These events prevent the participant’s daily activity and require intensive 
therapeutic intervention. 
Study staff should elicit from the participant or the parent(s)/LAR(s) the impact of AEs on the 
participant’s activities of daily living to assess severity and document it appropriately in the 
participant’s source documentation. Changes in the severity of an AE should be documented in 
the participant’s source documentation to allow an assessment of the duration of the event at 
each level of intensity to be performed. An AE characterized as intermittent requires 
documentation of onset and the duration of each episode. An AE that fluctuates in severity 
during the course of the event is reported once in the eCRF at the highest severity observed. 
7.4.9 Assessment of Causality 
The investigator’s assessment of an AE’s relationship to IP is part of the documentation process 
but is not a factor in determining what is or is not reported in the study. 
The investigator will assess causality (ie, whether there is a reasonable possibility that the IP 
caused the event) for all AEs and SAEs. The relationship will be characterized using the 
following classifications: 
Not related: There is not a reasonable possibility of a relationship to the IP. Participant did not 
receive the IP OR the temporal sequence of AE onset relative to administration of the IP is not 
reasonable OR the AE is more likely explained by a cause other than the IP. 
Related: There is a reasonable possibility of a relationship to the IP. There is evidence of 
exposure to the IP. The temporal sequence of AE onset relative to the administration of the IP is 
reasonable. The AE is more likely explained by the IP than by another cause. 
7.4.10 Reporting Adverse Events 
The investigator is responsible for reporting all AEs that are observed or reported at the times 
specified in the SoAs (Section 10.1), regardless of their relationship to IP or their clinical 
significance. If there is any doubt as to whether a clinical observation is an AE, the event should 
be reported. 

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All unsolicited AEs reported or observed during the study will be recorded on the AE page of the 
eCRF. Information to be collected includes type of event, time of onset, investigator-specified 
assessment of severity (impact on activities of daily living) and relationship to IP, time of 
resolution of the event, seriousness, any required treatments or evaluations, and outcome. The 
unsolicited AEs resulting from concurrent illnesses, reactions to concurrent illnesses, reactions to 
concurrent medications, or progression of disease states must also be reported. All AEs will be 
followed until they are resolved or stable or judged by the investigator to be not clinically 
significant, including ongoing SAEs after study completion. The Medical Dictionary for 
Regulatory Activities (MedDRA) will be used to code all unsolicited AEs. 
Any medical condition that is present at the time that the participant is screened but does not 
deteriorate should not be reported as an unsolicited AE. However, if it deteriorates at any time 
during the study, it should be recorded as an unsolicited AE. 
7.4.11 Reporting SAEs 
Prompt notification by the investigator to the Sponsor of an SAE is essential so that legal 
obligations and ethical responsibilities towards the safety of participants and the safety of a study 
intervention under clinical investigation are met. 
Any AE considered serious by the investigator or that meets SAE criteria (Section 7.4.2) must be 
reported to the Sponsor immediately (within 24 hours of becoming aware of the SAE) via the 
EDC system. The investigator will assess whether there is a reasonable possibility that the IP 
caused the SAE. The Sponsor will be responsible for notifying the relevant regulatory authorities 
of any SAE as outlined in the 21 US CFR Parts 312 and 320. The investigator is responsible for 
notifying the IRB directly. 
If the eCRF is unavailable at the time of the SAE, the following contact information is to be used 
for SAE reporting: 
• SAE Mailbox : Safety_Moderna@iqvia.com 
• SAE Hotline (United States and Canada): +1-866-599-1341 
• SAE Fax line (United States and Canada): +1-866-599-1342 
Regulatory reporting requirements for SAEs are described in Section 7.4.15. 
The investigator and any qualified designees are responsible for detecting, documenting, and 
recording events that meet the definition of an AE, including SAEs, and remain responsible for 
following up AEs that are serious, considered related to IP or study procedures, or that caused 
the participant to discontinue the study. 
 

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7.4.12 Time Period and Frequency for Collecting AE, AESI, and SAE Information 
Medical occurrences that begin before the start of IP dosing but after obtaining informed 
consent/assent will be recorded in the Medical History/Current Medical Conditions section of the 
eCRF and not in the AE section; however, if the condition worsens at any time during the study, 
it will be recorded and reported as an AE. 
Adverse events may be collected as follows: 
• Observing the participant 
• Receiving an unsolicited complaint from the participant or participant’s parent(s)/LAR(s) 
• Questioning the participant or participant’s parent(s)/LAR(s) in an unbiased and 
nonleading manner 
Solicited ARs will be collected from the day of injection through 6 days after each dose. Other 
(unsolicited) AEs will be collected from the day of injection through 28 days after each dose. 
Serious AEs (including AESIs) will be collected from the start of IP dosing until the last day of 
study participation. 
All SAEs and AESIs will be recorded and reported to the Sponsor or designee immediately and 
in all circumstances within 24 hours of becoming aware of the event via the EDC system. If a 
site receives a report of a new SAE or AESI from a study participant or receives updated data on 
a previously reported SAE or AESI and the eCRF has been taken offline, then the site can report 
this information on a paper SAE or AESI form using the SAE Mailbox, the SAE Hotline, or the 
SAE Fax line (Section 7.4.11). 
An abnormal value or result from a clinical or laboratory evaluation can also indicate an AE if it 
is determined by the investigator to be clinically significant (eg, leads to dose modification or 
study drug discontinuation, or meets any serious criteria). If this is the case, it must be recorded 
in the source document and as an AE on the appropriate AE form(s). The evaluation that 
produced the value or result should be repeated until that value or result returns to normal or is 
stabilized and the participant’s safety is not at risk. 
Investigators are not obligated to actively seek AEs or SAEs after end of the study participation. 
However, if the investigator learns of any SAE (including a death) at any time after a participant 
has withdrawn from or completed the study, and the investigator considers the event to be 
reasonably related to the IP or study participation, the investigator must promptly notify the 
Sponsor. 
 
 

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7.4.13 Method of Detecting AEs and SAEs 
Electronic diaries have specifically been designed for this study by the Sponsor. The diaries will 
include prelisted AEs (solicited ARs) and intensity scales; they will also include blank space for 
the recording of information on other AEs (unsolicited AEs) and concomitant 
medications/vaccinations. 
The investigator is responsible for the documentation of AEs regardless of treatment group or 
suspected causal relationship to IP. For all AEs, the investigator must pursue and obtain 
information adequate to determine the outcome of the AE and to assess whether the AE meets 
the criteria for classification as an SAE requiring immediate notification to the Sponsor or its 
designated representative. 
Care will be taken not to introduce bias when detecting AEs and/or SAEs. Open-ended and 
nonleading verbal questioning of the participant and participant’s parent(s)/LAR(s) is the 
preferred method to inquire about the occurrence of AE. 
7.4.14 Follow-up of AEs and SAEs 
After the initial AE/SAE report, the investigator is required to proactively follow each participant 
at subsequent visits and contacts. 
All AEs and SAEs will be treated as medically appropriate and followed until resolution, 
stabilization, the event is otherwise explained, or the participant is LTFU, as defined in 
Section 6.5. 
7.4.15 Regulatory Reporting Requirements for SAEs 
• Prompt notification by the investigator to the Sponsor of an SAE is essential so that legal 
obligations and ethical responsibilities towards the safety of participants and the safety of 
a study intervention under clinical investigation are met. 
• The Sponsor has a legal responsibility to notify both the local regulatory authority and 
other regulatory agencies about the safety of a study intervention under clinical 
investigation. The Sponsor will comply with country-specific regulatory requirements 
relating to safety reporting to the regulatory authority, IRBs, and investigators. 
• Investigator safety reports must be prepared for suspected unexpected serious adverse 
reactions according to local regulatory requirements and Sponsor policy and forwarded to 
investigators as necessary. 
• An investigator who receives an investigator safety report describing an SAE or other 
specific safety information (eg, summary or listing of SAEs) from the Sponsor will 

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review and then file it along with the IB and will notify the IRB, if appropriate according 
to local requirements. 
7.5 Safety Monitoring 
The CRO’s medical monitor, the Sponsor’s medical monitor, and the individual study site 
investigators will monitor safety throughout the study. 
7.5.1 Internal Safety Team 
An IST will review safety data throughout Part 1 of the study. For Part 1 dose-escalation and age 
de-escalation, based on the review of all available safety data through at least Day 8 (1 week 
after Dose 1 of mRNA-1273) for at least 75 participants at each dose level within the 6 years to 
< 12 years and 2 years to < 6 years age group, the IST will recommend whether dose-escalation 
and age de-escalation are appropriate. This process will then be repeated for all participants in 
the 25 and 50 µg dose levels within the lower age group of 6 months to < 2 years of age. An IST 
review of all available safety data through at least Day 36 (1 week after Dose 2 of mRNA-1273 
at each dose level) of at least 75 participants will be required prior to the administration of the 
second injection of the next higher dose. In addition, the IST will escalate any safety concerns to 
the DSMB. The frequency of IST meetings will be described in more detail in the IST charter. 
7.5.2 Data Safety Monitoring Board 
Safety oversight will be under the direction of a DSMB composed of external independent 
consultants with relevant expertise. Members of the DSMB will be independent from study 
conduct and free of conflict of interest. The DSMB will meet at pre-specified timepoints during 
the study to assess safety throughout study conduct. For the 6 years to < 12 years age group, the 
DSMB will review cumulative safety data for approximately 300 participants enrolled at the 
selected dose level in Part 1 before enrollment begins in Part 2. For both the middle age group 
(2 years to < 6 years) and the youngest age group (6 months to < 2 years) the DSMB will review 
cumulative safety data in both younger age groups (2 years to < 6 years; 6 months to < 2 years) 
combined and at all dose levels administered in Part 1 before start of Part 2 (blinded phase) for 
each age group. The DSMB will operate under the rules of an approved charter that will be 
written and reviewed at the organizational meeting of the DSMB. Details regarding the DSMB 
composition, responsibilities, procedures, and frequency of data review will be defined in its 
charter. 
If any of the study pause rules, described in Section 6.4, are met, the Sponsor will immediately 
suspend further enrollment and/or study dosing and the DSMB will convene on an ad hoc basis. 
The DSMB will review all available unblinded study data (as applicable) to help adjudicate any 
potential study pauses and make recommendations on further study conduct, including 

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requesting additional information, recommending stopping the study, recommending changes to 
study conduct and/or the protocol, or recommending additional operational considerations due to 
safety issues that arise during the study. 
The CEAC consisting of pediatric and adult cardiologists will review suspected cases of 
myocarditis, pericarditis, or myopericarditis to determine if they meet CDC criteria of “probable” 
or “confirmed” event, and to assess severity and enable the DSMB to make recommendations to 
the Sponsor to continue vaccine dosing. The CEAC will operate under the rules of an approved 
charter that will be written and reviewed at the organizational meeting of the CEAC. Details 
regarding the CEAC composition, responsibilities, procedures, and frequency of data review will 
be defined in its charter. 
In Part 2 (blinded phase), the Sponsor medical monitor may escalate to the DSMB chair if any 
safety concerns are identified, as described in the DSMB charter. 
7.6 Treatment of Overdose 
As the study treatment is to be administered by a healthcare professional, it is unlikely that an 
overdose will occur. Dose deviations will be tracked as protocol deviations (Section 10.2.8). 
7.7 Pharmacokinetics 
Pharmacokinetic parameters will not be evaluated in this study. 
7.8 Pharmacodynamics 
Pharmacodynamic parameters will not be evaluated in this study. 
7.9 Biomarkers 
Immunogenicity assessments are presented in Section 7.2. Biomarkers will not be evaluated in 
this study. 
7.10 Health Economics 
Health economics will not be evaluated in this study. 

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8 STATISTICAL ANALYSIS PLAN 
This section summarizes the planned statistical analysis strategy and procedures for the study. 
The details of statistical analysis will be provided in the statistical analysis plan (SAP), which 
will be finalized before the clinical database lock for the study. If changes are made to primary 
and/or key secondary objectives and hypotheses or the statistical methods related to those 
hypotheses after the study has begun but prior to any data unblinding, then the protocol will be 
amended (consistent with ICH Guideline E9). Changes to other secondary or exploratory 
analyses made after the protocol has been finalized, along with an explanation as to when and 
why they occurred, will be listed in the SAP or clinical study report (CSR) for the study. Ad hoc 
exploratory analyses, if any, will be clearly identified in the CSR. 
8.1 Blinding and Responsibility for Analyses 
Part 1 of this study will be open-label, blinding procedures will not be applicable. 
Part 2 of this study will be conducted in an observer-blind manner. The investigator, study staff, 
study participants, study site monitors, and Sponsor personnel (or its designees) will be blinded 
to the IP administered until study end, with the following exceptions: 
• Unblinded pharmacy personnel (of limited number) will be assigned to vaccine 
accountability procedures and will prepare and administer mRNA-1273 (or placebo) to 
all participants. These pharmacy personnel will have no study functions other than study 
vaccine management, documentation, accountability, preparation, and administration. 
They will not be involved in participant evaluations and will not reveal the identity of IP 
to either the participant or the blinded study site personnel involved in the conduct of the 
study unless this information is necessary in the case of an emergency. 
• Unblinded study site monitors, not involved in other aspects of monitoring, will be 
assigned as the IP accountability monitors. They will have responsibilities to ensure that 
study sites are following all proper IP accountability, preparation, and administration 
procedures. 
• An unblinded statistical and programming team will perform the primary analyses in 
Part 2 (Section 8.6.2). Sponsor team members will be pre-specified to be unblinded to the 
primary analysis results and will not communicate the results of primary analysis to the 
blinded investigators, study site staff, clinical monitors, or participants. 
The dosing assignment will be concealed by having the unblinded pharmacy personnel prepare 
the IP in a secure location that is not accessible or visible to other study staff. An opaque sleeve 
over the syringe used for injection will maintain the blind at the time of injection, as the doses 
containing mRNA-1273 will look different from those of placebo. Only delegated unblinded 

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study site staff will conduct the injection procedure. Once the injection is completed, only the 
blinded study staff will perform further assessments and interact with the participants. Access to 
the randomization code will be strictly controlled at the pharmacy. 
Part 3 is open label; however, if blinded administration is ongoing at the site, blinded procedure 
for Part 2 still applies. 
Blinded staff will be allowed to transport and administer vaccines if the site is no longer 
enrolling blinded participants in the study and if no second doses are pending for current blinded 
participants. This does not change the requirement for dose preparation by unblinded pharmacy 
staff. 
The planned study analyses are described in Section 8.6. 
8.1.1 Breaking the Blind 
A participant’s treatment assignment may be unblinded (Part 2 of the study) in the event of an 
SAE or other severe event, or if there is a medical emergency requiring the identity of the 
product to be known to properly treat a participant. If a participant becomes seriously ill or 
pregnant during the study, the blind will be broken if knowledge of the administered vaccine will 
affect that participant’s dosing options. In the event of a medical emergency requiring 
identification of the vaccine administered to an individual participant, the investigator will make 
every attempt to contact the Sponsor medical lead to explain the need for opening the code 
within 24 hours of opening the code. The investigator will be responsible for documenting the 
time, date, reason for the code break, and the names of the personnel involved. If a COVID-19 
vaccine is authorized or licensed for a specific age group before the end of the study, please refer 
to Section 3.3 for unblinding and/or cross-over plans. 
Participants under 6 years of age in Part 2 who have reached at least 6 months follow up after 
Dose 2 will be eligible for unblinding via a telephone call to learn which treatment they received. 
Participants who received placebo will be offered the option of cross-over vaccination with 
mRNA-1273 at that point. 
In addition to the aforementioned situations where the blind may be broken, the data will also be 
unblinded to a statistical team at specified time points for interim analyses as outlined in 
Section 8.6.1. 
Unblinding of still blinded participants based only on parental/LAR request and not related to a 
safety event or health concern before reaching at least 6 months follow up after Dose 2 will not 
be permitted to protect the data integrity of the blinded portion of the study. If a parent/LAR 
wishes to withdraw their child from the study, they may withdraw at any time but will only be 
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follow-up after Dose 2 or an unblinding trigger for the entire applicable age group is reached (eg, 
EUA granted for mRNA-1273 or a competitor vaccine. Participants who turn 5 years old will be 
eligible for unblinding and cross-over as of their 5th birthday given the availability of an 
authorized COVID-19 vaccine for 5-year-old children outside of the study since October 29, 
2021. 
8.2 Statistical Hypothesis 
If an accepted antibody threshold of protection against COVID-19 is established for the primary 
immunogenicity endpoint, the null hypothesis is that the percentage of participants on 
mRNA-1273 with serum antibody above the established threshold at Day 57 is ≤ 70% 
(ie, H0: percentage of participants on mRNA-1273 with serum antibody at Day 57 above the 
established threshold ≤ 70%). 
For each age group, the study will be considered to meet the immunogenicity endpoint if the 
95% confidence interval (CI) of percentage of participants on mRNA-1273 rules out 70% (lower 
bound of the 95% CI is > 70%). 
The null hypotheses may be updated when the information on an acceptable antibody threshold 
becomes available. In this case, the null hypothesis update will be provided in the SAP. 
If an accepted serum antibody threshold of protection against COVID-19 is not available for the 
primary immunogenicity endpoint, immune response as measured by GM value and SRR in each 
age group based on Day 57 antibody levels will be compared with Day 57 antibody levels from 
young adults (18 to 25 years of age) in Study P301. Noninferiority tests of 2 null hypotheses 
based on 2 coprimary endpoints will be performed, respectively. 
Part 1 or 2 Hypothesis Testing for Primary Series in Each Age Group 
Coprimary endpoint 1: antibody GM value at Day 57 
The null hypothesis H10: immunogenicity response to mRNA-1273, as measured by antibody 
GM value at Day 57, is inferior in children (in age groups 6 months to < 2 years, 2 years to 
< 6 years, and 6 years to < 12 years) compared with that in young adults (18 to 25 years of age) 
using mRNA-1273 Study P301 data. 
The noninferiority in antibody GM value in an age group in children compared with that in 
young adults (18 to 25 years of age) is demonstrated by meeting both success criteria: 
- 
The lower bound of the 95% CI of the geometric mean ratio (GMR) ruling out 0.67 
(lower bound ≥ 0.67) using a noninferiority margin of 1.5, AND 
- 
The GMR point estimate ≥ 0.8 (minimum threshold). 

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The GMR is the ratio of the GM value of SARS-CoV-2-specific antibody in children in an 
age group receiving mRNA-1273 in this Study P204 compared with the GM value of young 
adults (18 to 25 years of age) receiving mRNA-1273 in Study P301 at Day 57. 
Coprimary endpoint 2: antibody seroresponse rate at Day 57 
A definition of seroresponse will be provided in the SAP based on forthcoming information 
about assay performance. 
The null hypothesis H20: immunogenicity response to mRNA-1273 as measured by SRR at Day 
57 is inferior in children compared with that in young adults (18 to 25 years of age) in 
Study P301. 
The noninferiority in SRR in an age group in children compared with that in young adults (18 to 
25 years of age) is demonstrated by meeting both success criteria: 
- 
The lower bound of the 95% CI of the SRR difference ruling out -10% (ie, lower bound 
≥ -10%) using the noninferiority margin of 10%, AND 
- 
The SRR difference point estimate ≥ -5% (minimum threshold) 
The SRR difference is defined as the SRR in children receiving mRNA-1273 minus the SRR 
in young adults of 18 to 25 years of age receiving mRNA-1273 from Study P301. 
The study would be considered to meet the primary immunogenicity endpoint in an age group if 
the noninferiority in the age group compared with the young adults (18 to 25 years of age) is 
demonstrated based on both coprimary endpoints. 
Part 1 or Part 2 Hypothesis Testing for mRNA-1273 Booster Dose 
Booster dose coprimary endpoint 1: antibody GM at BD-Day 29 
The null hypothesis H10: immunogenicity response to mRNA-1273 booster dose as measured by 
Ab GM at BD-Day 29 in children in Study P204 is inferior compared with Ab GM that at Day 
57 (28 days after Dose 2) in the primary series of mRNA-1273 in adults (18 to 25 years of age) 
in Study P301. 
The noninferiority in Ab GM at BD-Day 29 in children receiving mRNA-1273 as a booster dose 
in Study P204 compared with Ab GM at Day 57 in the primary series in adults (18 to 25 years of 
age) in Study P301 will be demonstrated by the GMR 95% CI lower bound ≥ 0.67 using a 
noninferiority margin of 1.5. The GMR is defined as the ratio of GM value of Ab at BD-Day 29 
in Study P204 compared with Ab GM value at Day 57 (28 days after Dose 2) following the 
primary series of mRNA-1273 in Study P301. 

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Booster dose coprimary endpoint 2: antibody seroresponse rate at BD-Day 29 
The null hypothesis H20: immunogenicity response to mRNA-1273 booster dose as measured by 
SRR at BD-Day 29 in children in Study P204 is inferior compared with SRR at Day 57 (28 days 
after Dose 2) following the primary series of mRNA-1273 in adults (18 to 25 years of age) in 
Study P301. 
The noninferiority in SRR at BD-Day 29 in children receiving mRNA-1273 as a booster dose in 
Study P204 compared with SRR at Day 57 (28 days after Dose 2) following the primary series of 
mRNA-1273 will be demonstrated by the SRR 95% CI lower bound ≥ -10% using the 
noninferiority margin of 10%. The SRR difference is defined as the SRR at BD-Day 29 in Study 
P204 minus the rate at Day 57 (28 days after Dose 2) following the primary series of 
mRNA-1273 in adults in Study P301. The SRR is defined as a titer change from baseline (pre-
Dose 1) below the lower limit of quantification (LLOQ) to ≥ 4 × LLOQ, or at least a 4-fold rise 
if baseline is ≥ LLOQ. 
Booster dose primary immunogenicity objective for an age group in Part 2 will be considered to 
be met if the noninferiority in the age group compared with the adults (18 to 25 years of age) is 
demonstrated based on both coprimary endpoints. 
Part 3 Hypothesis Testing for Primary Series 
Primary series coprimary endpoint 1: antibody GM value at Day 57 
The null hypothesis H10: immunogenicity response to mRNA-1273, as measured by antibody 
GM value at Day 57, is inferior in children compared with that in adults (≥ 18 years of age) using 
mRNA-1273 Study P301 data. 
The noninferiority in antibody GM value in children in Part 3 compared with that in adults 
(≥ 18 years of age) is demonstrated by meeting the following success criterion: 
• The lower bound of the (1-alpha) CI of the GMR ruling out 0.67 (lower bound ≥ 0.67) 
using a noninferiority margin of 1.5. 
The 1-alpha can be 97.5% or 95% depending on the alpha level of 0.025 or 0.05 used for the 
hypothesis testing. The GMR is the ratio of the GM value of SARS-CoV-2-specific antibody in 
children receiving mRNA-1273 in this Study P204 compared with the GM value of adults 
(≥ 18 years of age) receiving mRNA-1273 in Study P301 at Day 57. 
Primary series coprimary endpoint 2: antibody seroresponse rate at Day 57 
The null hypothesis H20: immunogenicity response to mRNA-1273 as measured by SRR at Day 
57 is inferior in children compared with that in adults (≥ 18 years of age) in Study P301. 

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The noninferiority in SRR in children receiving mRNA-1273 in Part 3 compared with that in 
adults (≥ 18 years of age) is demonstrated by meeting the following success criterion: 
• The lower bound of the (1-alpha) CI of the SRR difference ruling out -10% (ie, lower 
bound ≥ -10%) using the noninferiority margin of 10%. 
The 1-alpha can be 97.5% or 95% depending on the alpha level of 0.025 or 0.05 used for the 
hypothesis testing. The SRR difference is defined as the SRR in children receiving mRNA-1273 
minus the SRR in adults of ≥ 18 years of age receiving mRNA-1273 from Study P301. 
Part 3 primary series primary immunogenicity objective will be considered to be met if the 
noninferiority in children compared with the adults (≥ 18 years of age) is demonstrated based on 
both coprimary endpoints. 
Part 3 Hypothesis Testing for Third Dose 
Third dose coprimary endpoint 1: antibody GM at BD-Day 29 
The null hypothesis H10: immunogenicity response to mRNA-1273 third dose as measured by Ab 
GM at BD-Day 29 in children in Study P204 is inferior compared with Ab GM that at Day 57 
(28 days after Dose 2) in the primary series of mRNA-1273 in adults (≥ 18 years of age) in Study 
P301. 
The noninferiority in Ab GM at BD-Day 29 in children receiving mRNA-1273 as a third dose in 
Study P204 compared with Ab GM at Day 57 in the primary series in adults (≥ 18 years of age) 
in Study P301 will be demonstrated by the GMR (1-alpha) CI lower bound ≥ 0.67 using a 
noninferiority margin of 1.5, where the 1-alpha can be 97.5% or 95% depending on the alpha 
level of 0.025 or 0.05 used for the hypothesis testing. The GMR is defined as the ratio of GM 
value of Ab at BD-Day 29 in Study P204 compared with Ab GM value at Day 57 (28 days after 
Dose 2) following the primary series of mRNA-1273 in Study P301. 
Third dose coprimary endpoint 2: antibody seroresponse rate at BD-Day 29 
The null hypothesis H20: immunogenicity response to mRNA-1273 third dose as measured by 
SRR at BD-Day 29 in children in Study P204 is inferior compared with SRR at Day 57 (28 days 
after Dose 2) following the primary series of mRNA-1273 in adults (≥ 18 years of age) in Study 
P301. 
The noninferiority in SRR at BD-D29 in children receiving mRNA-1273 as a third dose in Study 
P204 compared with SRR at Day 57 (28 days after Dose 2) following the primary series of 
mRNA-1273 will be demonstrated by the SRR (1-alpha) CI lower bound ≥ -10% using the 
noninferiority margin of 10%, where the 1-alpha can be 97.5% or 95% depending on the alpha 
level of 0.025 or 0.05 used for the hypothesis testing. The SRR difference is defined as the SRR 
at BD-Day 29 in Study P204 minus the rate at Day 57 (28 days after Dose 2) following the 

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primary series of mRNA-1273 in adults in Study P301. The SRR is defined as a titer change 
from baseline (pre-Dose 1) below the LLOQ to ≥ 4 × LLOQ, or at least a 4-fold rise if baseline is 
≥ LLOQ. 
Part 3 third dose primary immunogenicity objective will be considered to be met if the 
noninferiority in the age group compared with the adults (≥ 18 years of age) is demonstrated 
based on both coprimary endpoints. 
Justification of using Immunogenicity Subset of adults (≥ 18 years of age) from Study P301 as a 
comparator for hypothesis testing 
In Phase 3 pivotal Study P301 with more than 30,000 participants enrolled, VE against 
symptomatic COVID-19 based on adjudication committee assessment starting 14 days after 
second injection in the PP Set was demonstrated with VE estimate of 93.2% (95% CI: 91.0, 94.8) 
in adults ≥ 18 years in the final efficacy analysis (04 May 2021 database lock) in the blinded 
phase. In a random sample stratified by baseline SARS-CoV-2 status (negative vs. positive), age 
group (< 65 vs. ≥ 65 years) and race/ethnicity (minority vs. non-minority), there were n=1055 
participants ≥ 18 years of age in the PP Immunogenicity Subset who received mRNA-1273 
100 µg with baseline negative SARS-CoV-2 status. The observed pseudovirus neutralizing 
antibody (PsVNA) ID50 GMT at Day 57 was 1081.1 (95% CI: 1019.8, 1146.1) for adults 
≥ 18 years in Study P301. 
A separate random subset of young adults 18 to 25 years of age from Study P301 (n=305 in the 
PP Immunogenicity Subset receiving mRNA-1273 100 µg, of which n=296 have PsVNA assay 
results reported at Day 57) was selected for the purpose of immunobridging adolescents in Study 
P203 and children in Study P204 to young adults in Study P301. This subset of young adults 
with observed PsVNA ID50 GMT of 1301.3 (95% CI: 1172.3, 1444.5) at Day 57 was planned 
and used as a comparator in the primary immunogenicity analysis testing the noninferiority of 
immunogenicity in adolescents in Study P203 and children in Study P204. 
The observed Day 57 GMT of 1301.3 in young adults 18 to 25 years is approximately 1.2-fold 
higher compared with 1081.1 in adults ≥ 18 years of age with high VE established (VE estimate 
of 93.2% [95% CI: 91.0, 94.8]). The data suggest that adults ≥ 18 years of age may also be 
considered as a reference for immunobridging analyses. 
If a comparator age group of adults ≥ 18 years from Study P301 is used in a primary 
immunogenicity noninferiority hypothesis testing for children in Study P204, a sensitivity 
analysis may be performed by using different age group(s) (eg, 18 to 25 years, ≥ 65 years) from 
Study P301 as a comparator. 
 

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8.3 Power and Sample Size 
The initial age groups in Part 1 are for estimation purposes. With approximately 750 participants 
(approximately 375 participants at each dose level of mRNA-1273) in the initial 6 years to 
< 12 years age group, there is at least a 90% probability to observe at least 1 participant with an 
AE at a true AE rate of 1% for a given dose level. In each of the younger age groups (2 years to 
< 6 years and 6 months to < 2 years), the safety assessment will occur during the conduct of 
Part 2 after approximately 375 participants have been exposed to mRNA-1273 at the dose level 
selected for Part 2. For further details, please refer to Section 7.5.2. 
The sample size in the expansion (Part 2) is considered to be sufficient to support a safety 
database in the pediatric participants 6 months to < 12 years of age. With up to 3,000 participants 
each in the 6 years to < 12 years, 2 years to < 6 years, and 6 months to < 2 years of age groups 
exposed to mRNA-1273 at a given dose level in Part 2, the study has at least a 95% probability 
to observe at least 1 participant with an AE at a true 0.1% AE rate for a given dose level. 
The sample size in the lower dosing assessment (Part 3) is approximately 300 children 6 years to 
< 12 years of age receiving mRNA-1273 25 µg. There is at least a 90% probability to observe at 
least 1 participant with an AE at a true AE rate of 1% in this group. 
A subset of Full Analysis Set (FAS) participants (Immunogenicity Subset) in each age group will 
be selected for measuring immunogenicity data. The immunogenicity samples of the 
Immunogenicity Subset will be processed, and the analysis of primary immunogenicity endpoint 
will be based on the PP Immunogenicity Subset. 
If a threshold of protection is available, for the primary immunogenicity endpoint, with 
approximately 289 participants on mRNA-1273 in the PP Immunogenicity Subset of an age 
group, there will be at least 90% power to rule out 70% with a 2-sided 95% CI (lower bound of 
the 95% CI > 70%) for the percentage of mRNA-1273 participants exceeding the accepted 
threshold if the true rate of participants exceeding the threshold is 80%. 
If an acceptable antibody threshold of protection against COVID-19 is not available at the time 
of analysis for the primary immunogenicity endpoint, noninferiority tests of the 2 null 
hypotheses based on the 2 coprimary endpoints will be performed, respectively. The sample size 
calculation for each of the 2 noninferiority tests was performed, and the larger sample size was 
chosen for the study. 
• With approximately 289 participants receiving mRNA-1273 in the PP Immunogenicity 
Subset of each age group in Study P204 and young adults (18 to 25 years of age) in 
Study P301, there will be 90% power to demonstrate noninferiority of the immune 
response, as measured by the antibody GM value, in pediatric population at a 2‑sided 
alpha of 0.05, compared with that in young adults (18 to 25 years of age) in Study P301 

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receiving mRNA‑1273, assuming an underlying GMR value of 1, a noninferiority margin 
of 0.67 (or 1.5), and a point estimate minimum threshold of 0.8. The standard deviation 
of the natural log‑transformed levels is assumed to be 1.5. 
• With approximately 289 participants receiving mRNA-1273 in the PP Immunogenicity 
Subset of each age group in Study P204 and young adults (18 to 25 years of age) in 
Study P301, there will be at least 90% power to demonstrate noninferiority of the 
immune response as measured by SRR in children at a 2-sided alpha of 0.05, compared 
with that in young adults 18 to 25 years of age in Study P301 receiving mRNA-1273, 
assuming SRR of 85% in young adults of 18 to 25 years of age from Study P301, true 
SRR of 85% in children (or true rate difference is 0 compared with young adults from 
Study P301), a noninferiority margin of 10% and a point estimate minimum threshold of 
-5% in SRR difference. 
• In the 1273-P203 interim analysis (data snapshot on 08 May 2021), the observed SRRs at 
Day 57 were high in both 18 to 25 years of age group from Study P301 (98.6% with 95% 
CI: 96.6, 99.6) and 12 to17 years of age group (98.8% with 95% CI: 97.0, 99.7), based on 
pseudovirus nAb ID50 titers. For this Study P204, if the true SRRs were assumed to be 
95% or higher in both 18 to 25 years of age group from Study P301 and an age group in 
children, with between-group true difference within 4%, there will be a >90% power to 
demonstrate noninferiority by SRR in children compared with 18 to 25 years of age in 
Study P301, at a 2-sided alpha of 0.05. 
• 
Assuming approximately 25% of participants in the Immunogenicity Subset in Part 2 will 
not meet the criteria to be included in the PP Immunogenicity Subset, approximately 
528 participants in Part 2 (~396 receiving mRNA-1273 and ~132 receiving placebo) will 
be selected for the Immunogenicity Subset from which approximately 289 participants on 
mRNA-1273 will be suitable for the PP Immunogenicity Subset in Part 2. 
• In Part 2 for the booster dose primary immunogenicity analysis in an age group, with 
approximately 289 participants receiving mRNA-1273 booster dose in the PP 
Immunogenicity Subset with pre-booster negative SARS-CoV-2 in Study P204 and 
289 young adults (18 to 25 years of age) receiving mRNA-1273 100 µg primary series in 
Study P301, there will be a 90% power to demonstrate noninferiority of the immune 
response, as measured by the antibody GM value, in children receiving a booster dose 
compared with that in adults (18 to 25 years of age) receiving mRNA‑1273 primary 
series in Study P301, at a 2‑sided alpha of 0.05, assuming an underlying true GMR value 
of 1.0 and a noninferiority margin of 1.5. The standard deviation of the natural 
log‑transformed GMT levels is assumed to be 1.5. Also, if the true SRRs were assumed 
to be 95% or higher in children receiving mRNA-1273 booster dose in Study P204 and 

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adults receiving mRNA-1273 primary series in Study P301, with between-group true 
difference within 4%, there will be a > 90% power to demonstrate noninferiority by SRR 
in children receiving a booster dose compared with adults receiving primary series in 
Study P301, at a 2-sided alpha of 0.05. 
• In Part 3 for the primary series primary immunogenicity analysis, with approximately 
289 participants receiving mRNA-1273 25 µg primary series in the PP Immunogenicity 
Subset in Study P204 and 289 adults (≥ 18 years of age) receiving mRNA-1273 100 µg 
primary series in Study P301, there will be 84% power to demonstrate noninferiority of 
the immune response, as measured by the antibody GM value, in children compared with 
that in adults (≥ 18 years of age) receiving mRNA‑1273 in Study P301, at a 2‑sided alpha 
of 0.025, assuming a true GMR value of 1.0 and a noninferiority margin of 1.5. The 
standard deviation of the natural log‑transformed GMT levels is assumed to be 1.5. Also, 
if the true SRRs were assumed to be 95% or higher in children in Study P204 and adults 
from Study P301, with between-group true difference within 4%, there will be a > 90% 
power to demonstrate noninferiority by SRR in children compared with adults in Study 
P301, at a 2-sided alpha of 0.025. 
• In Part 3 for the third dose primary immunogenicity analysis, with approximately 
289 participants receiving a third dose of mRNA-1273 dose in the PP Immunogenicity 
Subset with pre-third dose negative SARS-CoV-2 in Study P204 and 289 adults 
(≥ 18 years of age) receiving mRNA-1273 100 µg primary series in Study P301, there 
will be a 84% power to demonstrate noninferiority of the immune response, as measured 
by the antibody GM value, in children receiving a third dose compared with that in adults 
(≥ 18 years of age) receiving mRNA‑1273 primary series in Study P301, at a 2‑sided 
alpha of 0.025, assuming an underlying true GMR value of 1.0 and a noninferiority 
margin of 1.5. The standard deviation of the natural log‑transformed GMT levels is 
assumed to be 1.5. Also, if the true SRRs were assumed to be 95% or higher in children 
receiving a third dose of mRNA-1273 dose in Study P204 and adults receiving mRNA-
1273 primary series in Study P301, with between-group true difference within 4%, there 
will be a > 90% power to demonstrate noninferiority by SRR in children receiving a third 
dose compared with adults receiving primary series in Study P301, at a 2-sided alpha of 
0.025. 
8.4 Analysis Sets 
The analysis sets are defined in Table 10. The analysis sets may be defined for Part 1 and Part 2 
separately. 

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Table 10: 
Analysis Sets 
Analysis Set 
Description 
Randomization Set 
Part 2: All participants who are randomly assigned, regardless of the 
participants’ treatment status in the study. 
Full Analysis Set (FAS) 
Part 1: All enrolled participants in Part 1 who receive at least 
1 injection of IP. 
Part 2: All randomly assigned participants who receive at least 
1 injection of IP. 
Part 3: All enrolled participants in Part 3 who receive at least 
1 injection of IP. 
Per Protocol (PP) Set 
All participants in the FAS who receive planned doses of IP per 
schedule, comply with the immunogenicity schedule, and have no 
major protocol deviations that impact key or critical data. Participants 
who are RT-PCR positive or seropositive at baseline will be excluded 
from the PP Set. The PP Set in Part 1 will be used for all analyses of 
immunogenicity in Part 1 unless specified otherwise. 
Immunogenicity Subset 
A subset of participants in the FAS will be selected for 
immunogenicity sampling and testing. 
Per Protocol Immunogenicity 
Subset 
A subset of participants in the FAS will be selected for 
immunogenicity testing. The PP Immunogenicity Subset includes 
participants selected for the Immunogenicity Subset who receive 
planned doses of IP per schedule, comply with immunogenicity 
testing schedule, and have no major protocol deviations that impact 
key or critical data. Participants who are RT-PCR positive or 
seropositive at baseline will be excluded from the PP 
Immunogenicity Subset, in addition to participants with HIV who are 
receiving highly active anti-retroviral therapy (HAART). The PP 
Immunogenicity Subset will be used for all analyses of 
immunogenicity unless specified otherwise. 
Safety Set 
All enrolled participants (in Part 1 and Part 3) and all randomly 
assigned participants (in Part 2) who receive at least 1 dose of IP. The 
Safety Set will be used for all analyses of safety except for solicited 
ARs. 
Safety Set for the booster/third dose phase will include all 
participants who receive a booster dose or third dose. 
Solicited Safety Set 
The Solicited Safety Set consists of participants in the Safety Set who 
contributed any solicited AR data. 
The Solicited Safety Set will be used for the analyses of solicited 
ARs. 
Modified Intent-to-Treat 
(mITT) Set 
All participants in the FAS who have no serologic or virologic 
evidence of prior SARS-CoV-2 infection before the first dose of IP 
(both negative RT-PCR test for SARS-CoV-2 and negative serology 
test based on bAb specific to SARS-CoV-2 nucleocapsid) at baseline. 

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Analysis Set 
Description 
Modified Intent-to-Treat-1 
(mITT1) Set 
All participants in the mITT Set excluding those who received the 
wrong treatment (ie, at least 1 dose received that is not as randomized 
or planned). 
Per Protocol Immunogenicity 
Subset for booster dose or 
third dose phase  
The PP Immunogenicity Subset for booster dose or third dose phase 
includes participants who received planned booster dose or third dose 
per schedule, complied with immunogenicity testing schedule, and 
have no major protocol deviations that impact key or critical data, 
with pre-booster or pre-third dose negative or positive SARS-CoV-2. 
The PP Immunogenicity Subset with pre-booster pre-third dose 
negative SARS-CoV-2 will be used for the primary immunogenicity 
analysis. 
Abbreviations: AR = adverse reaction; bAb = binding antibody; FAS = full analysis set; HAART = highly active 
anti-retroviral therapy; HIV = human immunodeficiency virus; IP = investigational product; mITT = modified 
intent-to-treat; mITT1 = modified intent-to-treat-1; PP = per protocol; RT-PCR = reverse transcriptase polymerase 
chain reaction; SARS-CoV-2 = severe acute respiratory syndrome coronavirus 2. 
8.5 Statistical Methods 
8.5.1 Baseline Characteristics and Demographics 
Demographic variables (eg, age, race, ethnicity) and baseline characteristics (eg, length/height, 
weight, and BMI) will be summarized by treatment group. Summary statistics (mean, standard 
deviation for continuous variables, and number and percentage for categorical variables) will be 
provided. 
8.5.2 Safety Analyses 
All safety analyses will be based on the Safety Set, except summaries of solicited ARs, which 
will be based on the Solicited Safety Set. All safety analyses will be provided by vaccination 
group (dose levels of mRNA-1273 and placebo) and by age group. Participants in Part 1 and 
Part 2 of the study and in different age groups who receive the same mRNA-1273 dose level may 
be combined for safety analysis. 
Safety and reactogenicity will be assessed by clinical review of all relevant parameters including 
solicited ARs (local and systemic events), unsolicited AEs, SAEs, MAAEs, AESIs, AEs leading 
to discontinuation, and physical examination findings. 
The number and percentage of participants with any solicited local AR, with any solicited 
systemic AR, and with any solicited AR during the 7-day follow-up period after each injection 
by toxicity grade will be provided. A 2-sided 95% exact CI using the Clopper-Pearson method 
will also be provided for the percentage of participants with any solicited AR. 

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The number and percentage of participants with unsolicited AEs, SAEs, MAAEs, severe AEs, 
and AEs leading to discontinuation from IP or withdrawal from the study will be summarized. 
Unsolicited AEs will be presented by MedDRA preferred term and system organ class. 
The number of events of solicited ARs, unsolicited AEs/SAEs, and MAAEs will be reported in 
summary tables accordingly. 
Solicited AR events (starting within 7 days after any injection) that are serious or lasting beyond 
Day 7 after any injection will also reported as unsolicited AEs. 
For all other safety parameters, descriptive summary statistics will be provided, and Table 11 
summarizes the analysis strategy for safety parameters. Further details will be described in the 
SAP. 
Table 11: 
Analysis Strategy for Safety Parameters 
Safety Endpoint 
Number and Percentage of 
Participants, Number of Events 
95% CI 
Any solicited AR (overall and by local, 
systemic) 
X 
X 
Any unsolicited AE 
X 
— 
Any SAE 
X 
— 
Any unsolicited MAAE 
X 
— 
Any unsolicited treatment-related AE 
X 
— 
Any treatment-related SAE 
X 
— 
Discontinuation due to AE 
X 
— 
Any severe AE 
X 
— 
Any treatment-related severe AE 
X 
— 
Abbreviations: AE = adverse event; AR = adverse reaction; CI = confidence interval; MAAE = medically attended 
adverse event; MedDRA = Medical Dictionary for Regulatory Activities; PT = preferred term; SAE = serious 
adverse event; SOC = system organ class. 
Note: 95% CI using the Clopper-Pearson method. X = results will be provided. Solicited ARs and unsolicited AEs 
will be summarized by SOC and PT coded by MedDRA. 
8.5.3 Immunogenicity Analyses 
The primary analysis population for immunogenicity will be the PP Immunogenicity Subset, 
unless specified otherwise. The primary objective of this study is to use the immunogenicity 
response to infer efficacy in participants aged 6 months to < 12 years at the dose level selected 
for expansion. For this objective, analyses of immunogenicity will be performed for each 
pediatric age group separately at the selected dose level based on the participants in the PP 
Immunogenicity Subset. For each pediatric age group, participants in the applicable study part in 
the PP Immunogenicity Subset may be used for immunogenicity primary analysis. Participants 

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from Part 1 and Part 2 who receive the same mRNA-1273 dose level selected for expansion may 
be combined for immunogenicity analyses. If the same dose level is selected for expansion for 
more than one age group, these age groups may be combined for immunogenicity analyses. 
An accepted antibody threshold of protection against COVID-19 may be available based on data 
from other mRNA-1273 studies or external data. If such a threshold of protection against 
COVID-19 is available, the number and percentage of participants with antibody greater than or 
equal to the threshold at Day 57 will be provided with a 2-sided 95% CI using the 
Clopper-Pearson method. For an age group, if the lower bound of the 95% CI on the 
mRNA-1273 group is > 70%, the primary immunogenicity endpoint of this study will be 
considered to be met for that age group. 
The number and percentage of participants with serum antibody greater than or equal to the 
threshold with 2-sided 95% CI will be provided at each postbaseline time point. The CI will be 
calculated using the Clopper-Pearson method. 
If an accepted serum antibody threshold of protection against COVID-19 is not established, 
immune response as measured by GM value and SRR in each age group based on Day 57 
antibody levels will be compared with that in young adults (18 to 25 years of age) using data 
from Study P301. An analysis of covariance model will be carried out with antibody at Day 57 as 
dependent variable and a group variable (a pediatric age group in Study P204 versus young 
adults [18 to 25 years of age] in Study P301) as the fixed variable for each pediatric age group. 
The GM values of the pediatric age group at Day 57 will be estimated by the geometric least 
square mean (GLSM) from the model. The GMR (ratio of GM values) will be estimated by the 
ratio of GLSM from the model. The corresponding 2-sided 95% CI will be provided to assess the 
difference in immune response between the pediatric age group (Study P204) compared with the 
young adults (18 to 25 years of age) in Study P301 at Day 57. For each pediatric age group, the 
noninferiority of GM value will be considered demonstrated if: 
- 
The lower bound of the 95% CI of the GMR is ≥ 0.67 based on the noninferiority margin 
of 1.5, AND 
- 
The GMR point estimate > 0.8 (minimum threshold). 
For Part 1 or Part 2 booster dose primary immunogenicity analysis of GM in children receiving 
mRNA-1273 booster dose, an analysis of covariance model will be performed to assess the 
difference in the immune response (Ab level) between BD-Day 29 in children receiving mRNA-
1273 booster dose (third dose) in Study P204 and Day 57 in young adults (≥18-25 years of age) 
receiving mRNA-1273 primary series in Study P301. In the analysis of covariance model, 
antibody titers at BD-Day 29 in P204 children and titers at Day 57 in P301 young adults will be a 
dependent variable, and a group variable (children in Study P204 and young adults in Study 

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P301) will be the fixed effect. The GMT will be estimated by the GLSM from the model, and its 
corresponding 95% CI will be provided for each group. The GMR (ratio of GMTs) for children 
in Study P204 with respect to young adults in Study P301 will be estimated by the ratio of 
GLSM from the model, and the corresponding 95% CIs will be provided. The 95% CI for GMR 
will be used to assess the between-group difference in immune response at BD-Day 29 in 
children in Study P204 compared with Day 57 after the primary vaccine series in young adults in 
Study P301. The noninferiority of post-booster GM in children will be considered demonstrated 
if the lower bound of the 95% CI of the GMR is ≥ 0.67 based on the noninferiority margin of 
1.5. 
For Part 3 primary series primary immunogenicity analysis of GM in children 6 years to 
< 12 years of age receiving mRNA-1273 25 µg which is half of the 50 µg dose level used in 
Part 2 for the same age group, the noninferiority hypothesis testing of GM in children compared 
with adults ≥ 18 years of age from Study P301 will be performed using an analysis of covariance 
model as described above. The noninferiority of GM in children in Part 3 will be considered 
demonstrated if the lower bound of the (1-alpha) CI of the GMR is ≥ 0.67 based on the 
noninferiority margin of 1.5, where the 1-alpha can be 97.5% or 95% depending on the alpha 
level of 0.025 or 0.05 used for the hypothesis testing. A sensitivity analysis may be conducted by 
using different age group(s) (eg, 18 to 25 years, ≥ 65 years) from Study P301 as a comparator. 
For Part 3 third dose primary immunogenicity analysis of GM in children receiving a third 
mRNA-1273 dose, an analysis of covariance model will be performed to assess the difference in 
the immune response at BD-Day 29 between children receiving mRNA-1273 third dose in Study 
P204 and adults (≥18 years of age) receiving mRNA-1273 booster dose (third dose) in Study 
P301. In the analysis of covariance model, antibody titers at BD-Day 29 in P204 children and 
titers at Day 57 in P301 young adults will be a dependent variable, and a group variable (children 
in Study P204 and adults in Study P301) will be the fixed effect. The GMT will be estimated by 
the GLSM from the model and its corresponding 95% will be provided for each group. The 
GMR for children in Study P204 with respect to adults in Study P301 will be estimated by the 
ratio of GLSM from the model and the corresponding 95% CIs will be provided. The 95% CI for 
GMR will be used to assess the between-group difference in immune response at BD-Day 29 in 
children in Study P204 compared with Day 57 following the primary vaccine series in adults in 
Study P301. The noninferiority of post-third dose GM in children will be considered 
demonstrated if the lower bound of the (1-alpha) CI of the GMR is ≥ 0.67 based on the 
noninferiority margin of 1.5. 
The number and percentage of participants with seroresponse due to vaccination will be provided 
with 2-sided 95% CI using the Clopper-Pearson method at each postbaseline time point with 
Day 57 being of the primary interest in the analyses for the mRNA-1273 primary series in Part 1 

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or Part 2. The SRR difference with 95% CI (using Miettinen-Nurminen score method) at Day 57 
will be provided between children receiving mRNA-1273 primary series in Study P204 Part 1 or 
Part 2 and young adults of 18 to 25 years of age receiving mRNA-1273 primary series in Study 
P301. For each pediatric age group in Part 1 or Part 2, the noninferiority of SRR will be 
considered demonstrated if: 
- 
The lower bound of the 95% CI of the SRR difference is ≥ -10% based on the 
noninferiority margin of 10%, AND 
- 
The SRR difference point estimate ≥ -5% (minimum threshold). 
For Part 1 or Part 2 booster dose primary immunogenicity analysis of seroresponse in children 
receiving mRNA-1273 booster dose (as applicable), the SRR with 95% CI (using Clopper-
Pearson method) will be summarized. The SRR difference with 95% CI (using Miettinen-
Nurminen score method) to compare post-booster SRR at BD-Day 29 in children in Study P204 
with the primary series SRR at Day 57 (28 days after Dose 2) in adults (18 to 25 years of age) in 
Study P301 will be computed. The SRR is defined as a titer change from baseline (pre-Dose 1) 
below the LLOQ to ≥ 4 × LLOQ, or at least a 4-fold rise if baseline is ≥ LLOQ. The 
noninferiority of SRR in children receiving mRNA-1273 booster dose will be considered 
demonstrated if the lower bound of the 95% CI of the SRR difference is ≥ -10% based on the 
noninferiority margin of 10%. 
For Part 3 primary series primary immunogenicity analysis of seroresponse in children 6 to 
< 12 years of age receiving mRNA-1273 25 µg which is half of the 50 µg dose level used in 
Part 2 for the same age group, the noninferiority hypothesis testing of SRR in children compared 
with adults ≥ 18 years of age from Study P301 will be performed using the analysis of SRR as 
described above. The SRR difference with (1-alpha) CI at Day 57 will be provided between 
children receiving mRNA-1273 primary series in Study P204 Part 3 and adults of ≥ 18 years of 
age receiving mRNA-1273 primary series in Study P301. The 1-alpha can be 97.5% or 95% 
depending on the alpha level of 0.025 or 0.05 used for the hypothesis testing. The noninferiority 
of SRR in children receiving mRNA-1273 25 µg primary series in Part 3 will be considered 
demonstrated if the lower bound of the (1-alpha) CI of the SRR difference is ≥ -10% based on 
the noninferiority margin of 10%. A sensitivity analysis may be conducted by using different age 
group(s) (eg, 18 to 25 years, ≥ 65 years) from Study P301 as a comparator. 
For Part 3 third dose primary immunogenicity analysis of seroresponse in children receiving a 
third dose of mRNA-1273, the SRR with (1-alpha) CI (using Clopper-Pearson method) will be 
summarized, where the 1-alpha can be 97.5% or 95% depending on the alpha level of 0.025 or 
0.05 used for the hypothesis testing. The SRR difference with (1-alpha)% CI (using Miettinen-
Nurminen score method) to compare post-third dose SRR at BD-Day 29 in children in 
Study P204 with the primary series SRR at Day 57 (28 days after Dose 2) in adults (≥ 18 years of 

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age) in Study P301 will be computed. The SRR is defined as a titer change from baseline (pre-
Dose 1) below the LLOQ to ≥ 4 × LLOQ, or at least a 4-fold rise if baseline is ≥ LLOQ. The 
noninferiority of SRR in children receiving a third dose of mRNA-1273 in Part 3 will be 
considered demonstrated if the lower bound of the (1-alpha) CI of the SRR difference is ≥ -10% 
based on the noninferiority margin of 10%. 
In addition, the GM value of anti-SARS-CoV-2-specific antibody with corresponding 95% CI 
will be provided at each time point. The 95% CIs will be calculated based on the t-distribution of 
the log-transformed values then back transformed to the original scale. For each age group, the 
geometric mean fold‑rise (GMFR) of specific nAb and bAb with corresponding 95% CI at each 
postbaseline time point over preinjection baseline at Day 1 and an earlier time point if applicable 
will be provided. Descriptive summary statistics including median, minimum, and maximum will 
also be provided. 
Multiplicity Adjustment Between Age Groups: 
A hierarchical sequential hypothesis testing (fixed-sequence method) will be used to adjust 
multiplicity to preserve the family-wise Type I error rate (alpha = 0.05), starting with the oldest 
age group, followed by the middle age group, and then followed by the youngest age group. The 
primary series immunogenicity coprimary endpoint hypotheses for the oldest age group (6 years 
to < 12 years of age) will be tested first at alpha level of 0.05 in Part 1 expansion or Part 2. If the 
testing in the oldest age group is statistically significant (meeting the noninferiority success 
criteria of the coprimary endpoints), the alpha level of 0.05 will be passed to the testing of the 
primary series coprimary endpoint hypotheses in the middle age group (2 years to < 6 years of 
age) in Part 2. If the testing in the middle age group is statistically significant at alpha level of 
0.05, then the alpha 0.05 is preserved for testing the primary series coprimary endpoint 
hypotheses in the youngest age group (6 months to < 2 years of age) in Part 2. 
If the hypothesis testing is statistically significant for all the primary series primary 
immunogenicity endpoints in Part 2, the alpha 0.05 is preserved for the hypothesis testing for the 
booster dose primary immunogenicity endpoint in Part 1 or Part 2, starting in the oldest age 
group (6 years to < 12 years of age), then the middle age group (2 years to < 6 years of age), 
followed by the youngest age group (6 months to < 2 years of age) for booster dose in applicable 
age groups in Part 1 or Part 2. The testing will continue through the sequence only until an 
endpoint is not statistically significant (did not meet specified noninferiority success criteria of 
any primary endpoint) in Part 1 or Part 2, in which case the testing will stop. If the hypothesis 
testing for all the booster dose primary endpoints in Part 2 is statistically significant (meeting the 
noninferiority success criteria of the primary endpoints), the alpha level of 0.05 will be passed to 
the hypothesis testing in Part 3. 

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In Part 3, half of the type I error rate 0.05 by alpha-splitting will be initially allocated to the 
hypothesis testing for the primary series immunogenicity coprimary endpoints, which will be 
tested initially at alpha level of 0.025. The second 0.025 will be reserved for Part 3 third dose 
hypothesis testing, and a fallback method will be used if applicable. 
• If the testing of the primary series coprimary endpoints in Part 3 is statistically significant at 
alpha level of 0.025 (meeting the noninferiority success criteria of the coprimary endpoints), 
a total of alpha 0.05 will be preserved for the hypothesis testing of the Part 3 third dose 
immunogenicity coprimary endpoints. 
• If the hypothesis testing of the primary series coprimary endpoints in Part 3 is not statistically 
significant at alpha level of 0.025 (not meeting any of the specific noninferiority success 
criteria of the coprimary endpoints), the remaining alpha level of 0.025 reserved will be used 
for the hypothesis testing of the Part 3 third dose immunogenicity coprimary endpoints. 
Further, if the hypothesis testing of the third dose coprimary endpoints in Part 3 is 
statistically significant at alpha level of 0.025, the unused alpha 0.025 will be passed back to 
re-testing of primary series coprimary endpoint hypothesis in Part 3 at alpha level of 
0.025+0.025=0.05 (a fallback method). 
8.5.4 Efficacy Analysis 
To evaluate the incidence of COVID-19 after vaccination with mRNA-1273 or placebo, the 
incidence rate will be provided by vaccination group, dose level, and age group, calculated as the 
number of cases divided by the total person-time. Participants in Part 1 and Part 2 of the study 
and in different age groups who receive the same mRNA-1273 dose level (if applicable) may be 
combined in the analysis. 
For serologically confirmed SARS-CoV-2 infection or COVID-19, regardless of 
symptomatology or severity, infection rate will be provided by vaccination group, dose level, and 
age group. The same analysis will be conducted for asymptomatic SARS-CoV-2 infection. 
The secondary efficacy analyses will be performed on the PP Set, with sensitivity analyses in 
FAS, modified Intent-to-Treat (mITT) Set, and modified Intent-to-Treat-1 (mITT1) Set. 
Analyses of the efficacy endpoints in Part 2 will be performed for the randomized blinded phase. 
Additional exploratory analyses will be conducted in the blinded and unblinded phases for 
participants randomized to mRNA-1273 in Part 2, and in the unblinded phase for participants 
who are originally randomized to the placebo arm and cross-over to mRNA-1273 after use of 
any COVID-19 vaccine is authorized or licensed for the participant’s age group. 
8.5.5 Exploratory Analyses 
Exploratory analyses will be described in the SAP before database lock. 

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8.5.6 Subgroup Analyses 
Subgroup analyses will be performed as described in the SAP. 
8.6 Study Analyses 
8.6.1 Interim Analyses 
Part 1: Interim analyses may be performed after all or a subset of participants (with 
immunogenicity samples collected for D1 and D57) have completed Day 57 within an age group 
in Part 1 (one optional interim analysis for each age group, 3 interim analyses total for the 3 age 
groups in Part 1). Analyses of safety and immunogenicity may be conducted at each interim 
analysis. 
Part 2: An interim analysis of immunogenicity and safety will be performed after all or a subset 
of participants have completed Day 57 (1 month after the second dose) in Part 1 or Part 2 within 
an age group. This interim analysis will be considered the primary analysis of immunogenicity 
for a given age group. Another interim analysis on safety may be performed after a different 
subset or all participants have completed Day 57 in an age group. Additional interim analysis of 
immunogenicity and safety may be performed after all or subset of participants who receive 
booster dose have completed BD-Day 29 after the booster dose in an age group. 
Part 3: An interim analysis of immunogenicity and safety will be performed after all or a subset 
of participants have completed Day 57 (1 month after the second dose) in Part 3 within an age 
group. This interim analysis will be considered the primary analysis of immunogenicity for the 
primary series in a given age group. A second interim analysis of immunogenicity and safety will 
be performed after all or a subset of participants have completed Day 177/BD-Day 29 (1 month 
after third dose). 
An interim analysis of safety for mRNA-1273.214 booster may be performed after all or subset 
of mRNA-1273.214 recipients have completed 6 months of follow-up after the booster dose. 
8.6.2 Final Analysis 
The final analysis of all endpoints will be performed after participants have completed all 
planned study procedures. Results of this analysis will be presented in a final CSR, including 
individual listings. 
Additional information about all study analyses may be provided in the SAP. 

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9 REFERENCES 
Adler Y, Charron P, Imazio M, Badano L, Barón-Esquivias G, Bogaert J, et al. 2015 ESC 
guidelines for the diagnosis and management of pericardial diseases: the task force for the 
diagnosis and management of pericardial diseases of the European society of cardiology (ESC) 
endorsed by: The European Association for Cardio-Thoracic Surgery (EACTS). Eur Heart J. 
2015 Nov 7;36(42):2921-64. 
Anderson EJ, Rouphael NG, Widge AT, Jackson LA, Roberts PC, Makhene M, et al; mRNA-
1273 Study Group. Safety and immunogenicity of SARS-CoV-2 mRNA-1273 vaccine in older 
adults. N Engl J Med. 2020;383(25):2427-38. 
Aretz HT. Myocarditis: the Dallas criteria. Hum Pathol. 1987 Jun;18(6):619-24. 
Baden LR, El Sahly HM, Essink B, Kotloff K, Frey S, Novak R, et al; COVE Study Group. 
Efficacy and safety of the mRNA-1273 SARS-CoV-2 vaccine. N Engl J Med. 
2021;384(5):403-16. 
Belhadjer Z, Méot M, Bajolle F, Khraiche D, Legendre A, Abakka S, et al. Acute heart failure in 
multisystem inflammatory syndrome in children in the context of global SARS-CoV-2 
pandemic. Circulation. 2020;142(5):429-36. 
Boehmer TK, DeVies J, Caruso E, van Santen KL, Tang S, Black CL, et al. Changing age 
distribution of the COVID-19 pandemic — United States, May–August 2020. MMWR Morb 
Mortal Wkly Rep. 2020;69(39):1404-9. 
Centers for Disease Control and Prevention (CDC). COVID data tracker: United States COVID-
19 cases and deaths by state [Internet]. 2020a [updated 2021 Jan 29; cited 2021 Jan 29]. 
Available from: https://covid.cdc.gov/covid-data-tracker/#cases. 
Centers for Disease Control and Prevention (CDC). COVID data tracker: demographic trends of 
COVID-19 cases and deaths in the US reported to CDC [Internet]. 2020b [updated 2021 Jan 29; 
cited 2021 Jan 29]. Available from: https://covid.cdc.gov/covid-data-tracker/#demographics. 
Centers for Disease Control and Prevention (CDC). COVID-19: symptoms of coronavirus 
[Internet]. 2020c [updated 2020 Dec 22; cited 2021 Jan 29]. Available from: 
https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/symptoms.html. 
Centers for Disease Control and Prevention (CDC). Multisystem inflammatory syndrome in 
children (MIS-C) associated with coronavirus disease 2019 (COVID-19) [Internet]. 2020d 
[updated 2020 Mar 27; cited 2021 Feb 16]. Available from: 
https://emergency.cdc.gov/han/2020/han00432.asp 

ModernaTX, Inc. 
mRNA-1273-P204 Protocol Amendment 9 
mRNA-1273 
Confidential 
Page 151 
Centers for Disease Control and Prevention (CDC). Coronavirus Disease 2019 Case Surveillance 
– United States, January 22 – May 30, 2020 [Internet]. 2020d [updated 2020 June 19; cited 2020 
Jun 20]. Available from: 
https://www.cdc.gov/mmwr/volumes/69/wr/mm6924e2.htm?s_cid=mm6924e2_w. 
Chen Y, Lu S, Jia H, Deng Y, Zhou J, Huang B, et al. A novel neutralizing monoclonal antibody 
targeting the N-terminal domain of the MERS-CoV spike protein. Emerg Microbes Infect. 
2017;6(5) :e37. 
Chen N, Zhou M, Dong X, Qu J, Gong F, Han Y, et al. Epidemiological and clinical 
characteristics of 99 cases of 2019 novel coronavirus pneumonia in Wuhan, China: a descriptive 
study. Lancet. 2020;395(10223) :507-13. 
Chin J, Magoffin RL, Shearer LA, Schieble JH, Lennette EH. Field evaluation of a respiratory 
syncytial virus vaccine and a trivalent parainfluenza virus vaccine in a pediatric population. Am 
J Epidemiol. 1969;89(4):449-63. 
ClinicalTrials.gov [Internet]. Bethesda (MD): National Library of Medicine (US). Identifier 
NCT03076385: Safety, tolerability, and immunogenicity of VAL-506440 in healthy adult 
subjects. [cited 2020 Jun 01]. Available from: 
https://clinicaltrials.gov/ct2/keydates/NCT03076385. 
ClinicalTrials.gov [Internet]. Bethesda (MD): National Library of Medicine (US). Identifier 
NCT03345043: Safety, tolerability, and immunogenicity of VAL-339851 in healthy adult 
subjects. [cited 2020 Jun 01]. Available from: 
https://clinicaltrials.gov/ct2/keydates/NCT03345043. 
ClinicalTrials.gov [Internet]. Bethesda (MD): National Library of Medicine (US). Identifier 
NCT03382405: Safety, reactogenicity, and immunogenicity of cytomegalovirus vaccines 
mRNA-1647 and mRNA-1443 in healthy adults. [cited 2020 Jun 01]. Available from: 
https://clinicaltrials.gov/ct2/keydates/NCT03382405. 
ClinicalTrials.gov [Internet]. Bethesda (MD): National Library of Medicine (US). Identifier 
NCT03392389: Safety, reactogenicity, and immunogenicity of mRNA-1653 in healthy adults. 
[cited 2020 Jun 01]. Available from: https://clinicaltrials.gov/ct2/keydates/NCT03392389. 
ClinicalTrials.gov [Internet]. Bethesda (MD): National Library of Medicine (US). Identifier 
NCT04283461: Safety and immunogenicity study of 2019-nCoV vaccine (mRNA-1273) for 
prophylaxis of SARS-CoV-2 infection (COVID-19). [cited 2020 Jun 01]. Available from: 
https://clinicaltrials.gov/ct2/keydates/NCT04283461. 

ModernaTX, Inc. 
mRNA-1273-P204 Protocol Amendment 9 
mRNA-1273 
Confidential 
Page 152 
ClinicalTrials.gov [Internet]. Bethesda (MD): National Library of Medicine (US). Identifier 
NCT04405076: Dose-confirmation study to evaluate the safety, reactogenicity, and 
immunogenicity of mRNA-1273 COVID-19 vaccine in adults aged 18 years and older. [cited 
2020 Aug 24]. Available from: https://clinicaltrials.gov/ct2/keydates/NCT04405076. 
ClinicalTrials.gov [Internet]. Bethesda (MD): National Library of Medicine (US). Identifier 
NCT04470427: A study to evaluate efficacy, safety, and immunogenicity of mRNA-1273 
vaccine in adults aged 18 years and older to prevent COVID-19; 2020 Jul 14. [cited 
2020 Aug 24]. Available from: https://clinicaltrials.gov/ct2/keydates/NCT04470427. 
Corbett KS, Edwards DK, Leist SR, Abiona OM, Boyoglu-Barnum S, Gillespie RA, et al. 
SARS-CoV-2 mRNA vaccine design enabled by prototype pathogen preparedness. Nature. 
2020a;586(7830):567-71. 
Corbett KS, Flynn B, Foulds KE, Francica JR, Boyoglu-Barnum S, Werner AP, et al. Evaluation 
of the mRNA-1273 vaccine against SARS-CoV-2 in nonhuman primates. N Engl J Med. 
2020b;383(16):1544-55. 
Corti D, Zhao J, Pedotti M, Simonelli L, Agnihothram S, Fett C, et al. Prophylactic and 
postexposure efficacy of a potent human monoclonal antibody against MERS coronavirus. Proc 
Natl Acad Sci U S A. 2015;112(33):10473-8. 
Cruz AT, Zeichner SL. COVID-19 in children: initial characterization of the pediatric disease. 
Pediatrics. 2020;145(6):e20200834. 
Department of Health and Human Services (DHHS), Food and Drug Administration, Center for 
Biologics Evaluation and Research (US). Guidance for industry: Toxicity grading scale for 
healthy adult and adolescent volunteers enrolled in preventative vaccine clinical trials. 
September 2007 [cited 2019 Apr 10] [10 screens]. Available from: m: 
https://www.fda.gov/downloads/BiologicsBloodVaccines/GuidanceComplianceRegulatoryInfor
mation/Guidances/Vaccines/ucm091977.pdf. 
Department of Health and Human Services (DHHS), Food and Drug Administration (US). 
Guidance for Industry, Investigators, and Institutional Review Boards. Guidance for industry, 
investigators, and institutional review boards: Conduct of clinical trials of medical products 
during the COVID-19 public health emergency. March 2020 [updated 2021 Jan 27; cited 2021 
Jan 29] [38 screens]. Available from: https://www.fda.gov/media/136238/download. 
Dufort EM, Koumans EH, Chow EJ, Rosenthal EM, Muse A, Rowlands J, et al; New York State 
and Centers for Disease Control and Prevention Multisystem Inflammatory Syndrome in 
Children Investigation Team. Multisystem inflammatory syndrome in children in New York 
State. N Engl J Med 2020;383(4):347-58. 

ModernaTX, Inc. 
mRNA-1273-P204 Protocol Amendment 9 
mRNA-1273 
Confidential 
Page 153 
Feldstein LR, Rose EB, Horwitz SM, Collins JP, Newhams MM, Son MB, et al; Overcoming 
COVID-19 Investigators; CDC COVID-19 Response Team. Multisystem inflammatory 
syndrome in U.S. children and adolescents. N Engl J Med 2020;383(4):334-46. 
Ferreira VM, Schulz-Menger J, Holmvang G, Kramer CM, Carbone I, Sechtem U, et al. 
Cardiovascular magnetic resonance in nonischemic myocardial inflammation: expert 
recommendations. J Am Coll Cardiol. 2018 Dec 18;72(24):3158-76. 
Fontanet A, Grant R, Tondeur L, Madec Y, Grzelak L, Cailleau I, et al. SARS-CoV-2 infection 
in primary schools in northern France: a retrospective cohort study in an area of high 
transmission. medRxiv. 2020;2020.06.25.20140178. Epub 2020 Jun 29. 
Fulginiti VA, Eller JJ, Downie AW, Kempe CH. Altered reactivity to measles virus: atypical 
measles in children previously immunized with inactivated measles virus vaccines. JAMA. 
1967;202(12):1075-80. 
Gargano JW, Wallace M, Hadler SC, Langley G, Su JR, Oster ME, et al. Use of mRNA 
COVID-19 vaccine after reports of myocarditis among vaccine recipients: update from the 
advisory committee on immunization practices – United States, June 2021. MMWR Morb 
Mortal Wkly Rep. 2021 Jul 9;70(27):977-82. 
Goldstein B, Giroir B, Randolph A; Members of the International Consensus Conference on 
Pediatric Sepsis. International pediatric sepsis consensus conference: definitions for sepsis and 
organ dysfunction in pediatrics. Pediatr Crit Care Med. 2005;6(1):2-8. 
Graham BS. Rapid COVID-19 vaccine development. Science. 2020;368(6494):945-6. 
Jackson LA, Anderson EJ, Rouphael NG, Roberts PC, Makhene M, Coler RN, et al; mRNA-
1273 Study Group. An mRNA vaccine against SARS-CoV-2 — preliminary report. N Engl J 
Med. 2020;383(20):1920-31. 
Johnson AG, Amin AB, Ali AR, Hoots B, Cadwell BL, Arora S, Avoundjian T, Awofeso AO, 
Barnes J, Bayoumi NS, Busen K, Chang C, Cima M, Crockett M, Cronquist A, Davidson S, 
Davis E, Delgadillo J, Dorabawila V, Drenzek C, Eisenstein L, Fast HE, Gent A, Hand J, Hoefer 
D, Holtzman C, Jara A, Jones A, Kamal-Ahmed I, Kangas S, Kanishka F, Kaur R, Khan S, King 
J, Kirkendall S, Klioueva A, Kocharian A, Kwon FY, Logan J, Lyons BC, Lyons S, May A, 
McCormick D; MSHI, Mendoza E, Milroy L, O'Donnell A, Pike M, Pogosjans S, Saupe A, Sell 
J, Smith E, Sosin DM, Stanislawski E, Steele MK, Stephenson M, Stout A, Strand K, Tilakaratne 
BP, Turner K, Vest H, Warner S, Wiedeman C, Zaldivar A, Silk BJ, Scobie HM. COVID-19 
Incidence and Death Rates Among Unvaccinated and Fully Vaccinated Adults with and Without 
Booster Doses During Periods of Delta and Omicron Variant Emergence - 25 U.S. Jurisdictions, 
April 4-December 25, 2021. MMWR Morb Mortal Wkly Rep. 2022 Jan 28;71(4):132-138. 

ModernaTX, Inc. 
mRNA-1273-P204 Protocol Amendment 9 
mRNA-1273 
Confidential 
Page 154 
Johnson RF, Bagci U, Keith L, Tang X, Mollura DJ, Zeitlin L, et al. 3B11-N, a monoclonal 
antibody against MERS-CoV, reduces lung pathology in rhesus monkeys following intratracheal 
inoculation of MERS-CoV Jordan-n3/2012. Virology. 2016;490 :49-58. 
Ju B, Zhang Q, Ge J, Wang R, Sun J, Ge X, et al. Human neutralizing antibodies elicited by 
SARS-CoV-2 infection. Nature. 2020;584(7819)115-9. 
Kim Y, Lee H, Park K, Park S, Lim JH, So MK, et al. Selection and characterization of 
monoclonal antibodies targeting Middle East respiratory syndrome coronavirus through a human 
synthetic Fab phage display library panning. Antibodies (Basel). 2019;8(3):42. 
Kim L, Whitaker M, O’Halloran A, Kambhampati A, Chai SJ, Reingold A, et al. Hospitalization 
rates and characteristics of children aged <18 years hospitalized with laboratory-confirmed 
COVID-19 — COVID-NET, 14 states, March 1–July 25, 2020. MMWR Morb Mortal Wkly Rep 
2020;69(32):1081-8. 
LaRovere KL, Riggs BJ, Poussaint TY, Young CC, Newhams MM, Maamari M, et al. 
Neurologic involvement in children and adolescents hospitalized in the United States for 
COVID-19 or multisystem inflammatory syndrome. JAMA Neurol. 2021;e210504. 
Leeb RT, Price S, Sliwa S, Kimball A, Szucs L, Caruso E, et al. COVID-19 trends among 
school-aged children — United States, March 1–September 19 2020. MMWR Morb Mortal 
Wkly Rep. 2020;69(39):1410-5. 
Licciardi F, Giani T, Baldini L, Favalli EG, Caporali R, Cimaz R. COVID-19 and what pediatric 
rheumatologists should know: a review from a highly affected country. Pediatr Rheumatol 
Online J. 2020;18:35. 
Link-Gelles R, DellaGrotta AL, Molina C, Clyne A, Campagna K, Lanzieri TM, et al. Limited 
secondary transmission of SARS-CoV-2 in child care programs — Rhode Island, June 1–
July 31, 2020. MMWR Morb Mortal Wkly Rep. 2020;69(34):1170-2. 
Paediatric Intensive Care Society (PICS). PICS statement: Increased number of reported cases of 
novel presentation of multi-system inflammatory disease [Internet]. 27 April 2020 [cited 2021 
Feb 01] [2 screens] Available from: https://pccsociety.uk/wp-content/uploads/2020/08/PICS-
statement-re-novel-KD-C19-presentation-v2-27042020.pdf. 
Robbiani DF, Gaebler C, Muecksch F, Lorenzi JC, Wang Z, Cho A, et al. Convergent antibody 
responses to SARS-CoV-2 in convalescent individuals. Nature. 2020;584(7821):437-42. 
Rothan HA, Byrareddy SN. The epidemiology and pathogenesis of coronavirus disease 
(COVID-19) outbreak. J Autoimmun. 2020;109:102433. 

ModernaTX, Inc. 
mRNA-1273-P204 Protocol Amendment 9 
mRNA-1273 
Confidential 
Page 155 
Rüggeberg JU, Gold MS, Bayas JM, Blum MD, Bonhoeffer J, Friedlander S, et al. Anaphylaxis: 
case definition and guidelines for data collection, analysis, and presentation of immunization 
safety data. Vaccine. 2007;25(31):5675-84. 
Schwartz NG, Moorman AC, Makaretz A, Chang KT, Chu VT, Szablewski CM, et al. 
Adolescent with COVID-19 as the source of an outbreak at a 3-week family gathering — four 
states, June‒July 2020. MMWR Morb Mortal Wkly Rep. 2020;69(40):1457-9. 
Shen KL, Yang YH, Jiang RM, Wang TY, Zhao DC, Jiang Y, Lu XX, et al. Updated diagnosis, 
treatment and prevention of COVID‑19 in children: experts’ consensus statement (condensed 
version of the second edition). World J Pediatr. 2020:16(3)232-9. 
Szablewski CM, Chang KT, Brown MM, Chu VT, Yousaf AR, Anyalechi N, et al. SARS-CoV-2 
transmission and infection among attendees of an overnight camp — Georgia, June 2020. 
MMWR Morb Mortal Wkly Rep 2020;69(31):1023-5. 
Thomas SJ, Yoon IK. A review of Dengvaxia®: development to deployment. Hum Vaccin 
Immunother. 2019;15(10):2295-314. 
Topjian AA, Raymond TT, Atkins D, Chan M, Duff JP, Joyner BL Jr, et al. Part 4: Pediatric 
basic and advanced life support: 2020 American Heart Association Guidelines for 
cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 
2020;142(suppl 2):S469-S523. 
Verdoni L, Mazza A, Gervasoni A, Martelli L, Ruggeri M, Ciuffreda M, et al. An outbreak of 
severe Kawasaki-like disease at the Italian epicentre of the SARS-CoV-2 epidemic: an 
observational cohort study. Lancet 2020;395(10239):1771-8. 
Vogel TP, Top KA, Karatzios C, Hilmers DC, Tapia LI, Moceri P, et al. Multisystem 
inflammatory syndrome in children and adults (MIS-C/A): case definition and guidelines for data 
collection, analysis, and presentation of immunization safety data. Vaccine. Submitted 2020. 
Available from: https://brightoncollaboration.us/wp-content/uploads/2020/12/submitted-pdf-
build.pdf. 
Wang L, Shi W, Joyce MG, Modjarrad K, Zhang Y, Leung K, et al. Evaluation of candidate 
vaccine approaches for MERS-CoV. Nat Commun. 2015;6:7712. 
Wang L, Shi W, Chappell JD, Joyce MG, Zhang Y, Kanekiyo M, et al. Importance of 
neutralizing monoclonal antibodies targeting multiple antigenic sites on the Middle East 
respiratory syndrome coronavirus spike glycoprotein to avoid neutralization escape. J Virol. 
2018;92(10):e02002-17. 
Widge AT, Rouphael NG, Jackson LA, Anderson EJ, Roberts PC, Makhene M, et al. Durability 
of responses after SARS-CoV-2 mRNA-1273 vaccination. N Engl J Med. 2021;384(1):80-2. 

ModernaTX, Inc. 
mRNA-1273-P204 Protocol Amendment 9 
mRNA-1273 
Confidential 
Page 156 
Widjaja I, Wang C, van Haperen R, Gutiérrez-Álvarez J, van Dieren B, Okba NM, et al. 
Towards a solution to MERS: protective human monoclonal antibodies targeting different 
domains and functions of the MERS-coronavirus spike glycoprotein. Emerg Microbes Infect. 
2019;8(1):516-30. 
World Health Organization (WHO). Dengue vaccine: WHO position paper, September 2018 – 
recommendations. Vaccine. 2019;37(35):4848-9. 
World Health Organization (WHO). Coronavirus disease 2019 (COVID-19): situation report – 
157. 2020a June 25 (cited 2020 Jun 26). Available from: https://www.who.int/docs/default-
source/coronaviruse/situation-reports/20200625-covid-19-sitrep-157.pdf?sfvrsn=423f4a82_2. 
World Health Organization (WHO). WHO coronavirus disease (COVID-19) dashboard. 
2020b Sep 28 (cited 2021 Jan 30). Retrieved from: https://covid19.who.int/. 
Wrapp D, Wang N, Corbett KS, Goldsmith JA, Hseih CL, Abiona O, et al. Cryo-EM structure of 
the 2019-nCoV spike in the prefusion conformation. Science. 2020;367(6483) :1260-3. 
Yu X, Zhang S, Jiang L, Cui Y, Li D, Wang D, et al. Structural basis for the neutralization of 
MERS-CoV by a human monoclonal antibody MERS-27. Sci Rep. 2015;5:13133. 
Zambrano LD, Newhams MM, Olson SM, Halasa NB, Price AM, Boom JA, Sahni LC, 
Kamidani S, Tarquinio KM, Maddux AB, Heidemann SM, Bhumbra SS, Bline KE, Nofziger 
RA, Hobbs CV, Bradford TT, Cvijanovich NZ, Irby K, Mack EH, Cullimore ML, Pannaraj PS, 
Kong M, Walker TC, Gertz SJ, Michelson KN, Cameron MA, Chiotos K, Maamari M, Schuster 
JE, Orzel AO, Patel MM, Campbell AP, Randolph AG; Overcoming COVID-19 Investigators. 
Effectiveness of BNT162b2 (Pfizer-BioNTech) mRNA Vaccination Against Multisystem 
Inflammatory Syndrome in Children Among Persons Aged 12-18 Years - United States, July-
December 2021. MMWR Morb Mortal Wkly Rep. 2022 Jan 14;71(2):52-58. 
Zent O, Arras-Reiter C, Broeker M, Hennig R. Immediate allergic reactions after vaccinations – 
a post-marketing surveillance review. Eur J Pediatr. 2002;161:21-5. 

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10 SUPPORTING DOCUMENTATION AND OPERATIONAL 
CONSIDERATIONS 
10.1 APPENDIX 1: Schedule of Assessments 
The SoA for Study Arms 1 through 13 is presented in Table 12. The SoA for participants who 
received an optional booster dose (for Parts 1 and 2) with mRNA-1273 under Protocol 
Amendment 7 is presented in Table 15. For participants who choose to receive a booster dose 
with mRNA-1273.214 under Protocol Amendment 9, please see Table 19 for the 
mRNA-1273.214 booster dose SoA. The SoA for Study Arm 14 is presented in Table 17. The 
SoA for placebo recipient cross-over vaccination with mRNA-1273 if any COVID-19 vaccine is 
authorized or licensed for participant’s age group or another unblinding trigger is reached 
(Section 3.3) is presented in Table 13. 
If a participant cannot attend a study site visit (scheduled or unscheduled), with the exception of 
Screening, Day 1, and Day 29, a home visit is acceptable if performed by appropriately delegated 
study site staff or a home healthcare service provided by the Sponsor (Section 7). If neither a 
participant visit to the study site nor a home visit to the participant is possible (with the 
aforementioned exceptions), a safety telephone call should be performed that includes the 
assessments scheduled for the safety telephone calls. 
The blood sampling schedule for exploratory serology and CMI in Part 2 of the study is 
presented in Table 14. For participants who received a booster dose under protocol Amendment 
7, see Table 16 for the booster dose phlebotomy schedule. The blood sampling schedule for 
participants opting for booster dose in Parts 1 and 2 is presented in Table 16. The blood sampling 
for Part 3 of the study is presented in Table 18. 
 

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Table 12: Schedule of Assessments for Parts 1 and 2, Study Arms 1 Through 13 
For participants who received a booster dose with mRNA-1273 under Protocol Amendment 7, please see Table 15 for the 
mRNA-1273 booster dose SoA. 
For participants who choose to receive a booster dose with mRNA-1273.214 under Protocol Amendment 9, please see Table 19 
for the mRNA-1273.214 booster dose SoA. 
Visit Number 
0 
1 
2 
3 
3A 
4 
 4S 
5 
 
6 
 
7 
Type of Visit 
C 
C 
TMV 
C 
C 
TMV 
C 
C 
SFU 
C 
SFU 
C 
Month Time Point 
 
M0 
 
M1 
 
 
 
M2 
eDiary 
SC 
M7 
eDiary 
SC 
M13 
Study Visit Day 
D-28 to D-1 
(Screening)1 
D1 (Baseline) 
D8 
D292 
D30 
D362 
D432,3 
D572, 4 
Every 4 weeks  
D71 – D1832, 5 
Every 4 weeks  
D85– D1972, 6 
D2092, 4 
Every 4 weeks 
D223– D3632, 5 
Every 4 weeks 
D237– D3772, 6 
D3942, 4 
Window Allowance (Days) 
- 
- 
+ 3 
+ 7 
+3 
+ 3 
± 2 
+ 7 
± 3 
± 3 
± 14 
± 3 
± 3 
± 14 
Days Since Most Recent Injection 
- 
0 
7 
28 
1 
7 
14 
28 
-  
- 
180 
- 
- 
365 
Informed consent/assent form, 
demographics, concomitant 
medications, medical history  
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
Review of inclusion and exclusion 
criteria 
X 
X 
 
 
 
 
 
 
 
 
 
 
 
 
Physical examination including body 
temperature, length/height, weight, and 
BMI7 
X 
X 
 
X 
 
 
 
X 
X 
 
 
X 
 
 
X 
Pregnancy test8 
X 
X 
 
X 
 
 
 
 
 
 
 
 
 
 
Randomization 
 
X 
 
 
 
 
 
 
 
 
 
 
 
 
Study injection (including 30-minute 
post-dose observation period) 
 
X 
 
X 
 
 
 
 
 
 
 
 
 
 
Blood sample for vaccine 
immunogenicity (Part 1)9 
 
X 
 
 
 
 
 
X19 
 
 
X19 
 
 
X19 
Blood sample for vaccine 
immunogenicity (Part 2)10 
 
X 
 
X 
 
 
 
X 
 
 
X 
 
 
X 

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Visit Number 
0 
1 
2 
3 
3A 
4 
 4S 
5 
 
6 
 
7 
Type of Visit 
C 
C 
TMV 
C 
C 
TMV 
C 
C 
SFU 
C 
SFU 
C 
Month Time Point 
 
M0 
 
M1 
 
 
 
M2 
eDiary 
SC 
M7 
eDiary 
SC 
M13 
Study Visit Day 
D-28 to D-1 
(Screening)1 
D1 (Baseline) 
D8 
D292 
D30 
D362 
D432,3 
D572, 4 
Every 4 weeks  
D71 – D1832, 5 
Every 4 weeks  
D85– D1972, 6 
D2092, 4 
Every 4 weeks 
D223– D3632, 5 
Every 4 weeks 
D237– D3772, 6 
D3942, 4 
Window Allowance (Days) 
- 
- 
+ 3 
+ 7 
+3 
+ 3 
± 2 
+ 7 
± 3 
± 3 
± 14 
± 3 
± 3 
± 14 
Days Since Most Recent Injection 
- 
0 
7 
28 
1 
7 
14 
28 
-  
- 
180 
- 
- 
365 
Blood sample for exploratory serology 
and cell-mediated immunity (Part 2)3,10 
 
X 
 
 
 
 
X 
 
 
 
X 
 
 
X 
Blood sample for potential biomarker 
analysis (Part 2)10,11 
 
 
 
 
X11 
 
 
 
 
 
 
 
 
 
Nasal swab sample for SARS-CoV-212 
 
X 
 
X 
 
 
X 
X 
 
 
X 
 
 
X 
Unscheduled visit13 
 
 
X 
X 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
eDiary activation for recording 
solicited ARs (7 days)15 
 
X 
 
X 
 
 
 
 
 
 
 
 
 
 
Review of eDiary data 
 
 
X 
 
 
X 
 
 
 
 
 
 
 
 
Follow-up safety telephone calls16 
 
 
 
 
 
 
 
 
 
X 
 
 
X 
 
Recording of unsolicited AEs 
 
X 
X 
X 
X 
X 
X 
X 
 
 
 
 
 
 
Recording of MAAEs and concomitant 
medications relevant to or for the 
treatment of the MAAE17 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Recording of SAEs and concomitant 
medications relevant to or for the 
treatment of the SAE17,18 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Recording of AESIs (eg, MIS-C, 
myocarditis/pericarditis)18 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Recording of concomitant medications 
and nonstudy vaccinations17 
 
X 
X 
X 
X 
X 
X 
X 
 
 
 
 
 
 
Study completion 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
Abbreviations: AE = adverse event; AESI = adverse event of special interest; AR = adverse reaction; BMI = body mass index; C = clinic visit; CMI = cell-
mediated immunity; COVID-19 = coronavirus disease 2019; D = day; eCRF = electronic case report form; EDC = electronic data capture; eDiary = electronic 

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diary; FDA = Food and Drug Administration; IP = investigational product; IRB = institutional review board; LAR = legally authorized representative; 
M = month; MAAE = medically attended adverse event; MIS-C = multisystem inflammatory syndrome in children; RT-PCR = reverse transcriptase 
polymerase chain reaction; S = spike; SAE = serious adverse event; SARS-CoV-2 = severe acute respiratory syndrome coronavirus 2; SC = safety (telephone) 
call; SFU = safety follow-up; TMV = telemedicine visit; VTEU = Vaccine and Treatment Evaluation Units. 
Note: In accordance with FDA Guidance on Conduct of Clinical Trials of Medical Products during COVID-19 Public Health Emergency (FDA March 2020), 
investigators may convert study site visits to home visits or telemedicine visits (with the exception of Screening, Day 1, and Day 29) with the approval of the 
Sponsor. 
1. 
Screening Visit and Day 1 may be combined on the same day. Additionally, the Screening Visit may be performed over multiple visits if performed 
within the 28-day screening window. 
2. 
If the visit for the second dose (Day 29) is disrupted and cannot be completed at Day 29 (+7 days) as a result of the COVID-19 pandemic (self-
quarantine or disruption of study site activities following business continuity plans and/or local government mandates for “stay at home” or “shelter in 
place”), the visit window may be extended to Day 29 + 21 days. When the extended visit window is used, the remaining study visits should be 
rescheduled to follow the intervisit interval from the actual date of the second dose. Refer to Section 6.1.1 for individual participant criteria for delay of 
study vaccination. 
3. 
To be conducted during Part 2 of the study in a cohort of participants at selected VTEU sites only. 
4. 
All scheduled study visits should be completed within the respective visit windows. If the participant is not able to attend a study site visit as a result of 
the COVID-19 pandemic (self-quarantine or disruption of study site activities following business continuity plans and/or local government mandates for 
“stay at home” or “shelter in place”), a telemedicine visit should be conducted in place of the study site visit. The telemedicine visit should encompass 
all scheduled visit assessments that can be completed remotely, such as assessment for AEs and concomitant medications (eg, as defined in scheduled 
safety telephone calls). Home visits will be permitted for all nondosing visits, with the exception of Screening, if a participant cannot visit the study site 
as a result of the COVID-19 pandemic. Home visits must be permitted by the study site IRB and the participant’s parent(s)/LAR(s) via informed consent 
and have prior approval from the Sponsor (or its designee). 
5. 
Safety follow-up via an eDiary questionnaire will be performed every 4 weeks from Day 71 to Day 183 and again from Day 223 to Day 363. 
6. 
Safety follow-up via a safety telephone call will be performed every 4 weeks from Day 85 to Day 197 and again from Day 237 to Day 377. 
7. 
A full physical examination, including body temperature (oral [for participants > 4 years of age] or tympanic [for participants ≤ 4 years of age]), 
length/height, and weight, will be performed at the Screening Visit or on Day 1. Symptom-directed physical examination will be performed on Day 1, 
Day 29, Day 43 (if the visit is applicable), Day 57, Day 209, and Day 394 and may be performed at other time points at the discretion of the 
investigator. Body mass index will be calculated only at Screening Visit. Body temperature (oral/tympanic) should be measured on each injection day 
prior to injection. On each injection day before injection and again 7 days after injection, the injection site should be examined. Any clinically 
significant finding identified during a study visit should be reported as an MAAE. Participants who are febrile (body temperature ≥ 38.0°C/≥ 100.4°F) 
before injection on Day 1 or Day 29 must have the visit rescheduled within the relevant visit window to receive the injection. Afebrile participants with 
minor illnesses may be injected at the discretion of the investigator. 
8. 
Pregnancy test at Screening and Day 1 and before the second study injection will be a point-of-care urine test and will be performed if deemed 
appropriate by the investigator. At the discretion of the investigator, a pregnancy test either via blood or point-of-care urine test can be performed at any 
time during the study. 
9. 
On Day 1, sample must be collected prior to randomization and dosing. If a Day 1 (baseline) blood sample cannot be obtained in Part 1, the participant 
will be considered either a screen failure due to inability to satisfy inclusion criterion 3 or could be scheduled for rescreening. Participants may be 
rescreened 1 time, either within the same screening period for Part 1 or for a new screening period for Part 2 later in the study. If the participant is 
rescreened and a blood sample still cannot be obtained, then he/she will be considered a screen failure due to inability to satisfy inclusion criterion 3. 

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10. On Day 1, sample must be collected prior to randomization and dosing. On Day 29, sample must be collected prior to dosing. In Part 2, participants in 
each age group will be assigned to 1 of 5 phlebotomy cohorts (Table 14). Participants in 3 of these 5 cohorts will provide blood specimens for 
immunogenicity at the following time points: Day 1, Day 57, and one of Day 29, Day 209, or Day 394 (such that each participant provides a total of 3 
blood samples only). Participants in the Cohort D (remainder of the age group) will provide a blood sample at Day 1 (prior to randomization and the 
first dose) and within 4 days of receiving Dose 2 at Day 30 (+3 days) for storage and potential future biomarker testing. A fifth cohort of participants 
(selected VTEU sites only) will provide blood samples for assessment of exploratory serology and CMI (S protein-specific T-cell responses) on Day 1, 
Day 43, Day 209, and D394. Table 14 provides the blood sampling schedule in Part 2 of the study. If a Day 1 (baseline) blood sample cannot be 
obtained in either Part 1 or Part 2, the participant will be considered either a screen failure due to inability to satisfy inclusion criterion 3 or could be 
rescheduled for rescreening. Participants may be rescreened 1 time, either within the same screening period for Part 1 or Part 2 or in a new screening 
period of Part 2 if the initial screening was in Part 1. If the participant is rescreened and a blood sample still cannot be obtained, then he/she will be 
considered a screen failure due to inability to satisfy inclusion criterion 3. 
11. Part 2, Cohort D participants only, one ~4 mL blood draw. For participants already enrolled in Cohort D prior to Protocol Amendment 4, this blood 
draw will be optional and confirmed at time of re-consenting; for all participants newly enrolled into Cohort D under Amendment 4, it is mandatory. 
12. The nasal swab sample (collected before dosing on injection day) will be used to ascertain the presence of SARS-CoV-2 via RT-PCR. 
13. An unscheduled visit may be prompted by reactogenicity issues or new or ongoing AEs. 
14. At each injection visit, participants’ parent(s)/LAR(s) will record data into the eDiary starting approximately 30 minutes after injection under the 
supervision of the study site staff to ensure successful entry of assessment. Participants’ parent(s)/LAR(s) will continue to record entries in the eDiary 
after they leave the study site, preferably in the evening and at the same time each day, on the day of injection and for 6 days following injection. If a 
solicited local or systemic AR continues beyond Day 7 after vaccination, the participant’s parent(s)/LAR(s) will be prompted to capture details of the 
solicited local or systemic AR in the eDiary until the AR is resolved or the next IP injection occurs, whichever occurs first. Capturing details of ARs in 
the eDiary should not exceed 28 days after each vaccination. Adverse reactions recorded in eDiaries beyond Day 7 should be reviewed by the study site 
staff either during the next scheduled telephone call or at the next study site visit. 
15. Trained study site personnel will call all participants to collect information relating to any MAAEs, SAEs, AEs leading to study withdrawal and 
information on concomitant medications associated with those events and any nonstudy vaccinations. In addition, study personnel will collect 
information on known participant exposure to someone with known COVID-19 or SARS-CoV-2 infection and on any COVID-19 symptoms the 
participant may experience. 
16. All concomitant medications and nonstudy vaccinations will be recorded through 28 days after each injection; all concomitant medications relevant to or 
for the treatment of an SAE or MAAE will be recorded from Day 1 through the final visit (Day 394). Non-Study COVID-19 vaccines should be 
reported through EOS. 
17. In addition to MIS-C and myocarditis and/or pericarditis, a list of AESIs pertinent to this study may be referenced in the list of AESIs that is maintained 
by the Sponsor and provided to each investigator. All SAEs and AESIs will be reported to the Sponsor or designee immediately and in all circumstances 
within 24 hours of becoming aware of the event via the EDC system. If a site receives a report of a new SAE or AESI from a study participant or 
receives updated data on a previously reported SAE or AESI and the eCRF has been taken offline, then the site can report this information on a paper 
SAE or AESI form using the SAE Mailbox, the SAE Hotline, or the SAE Fax line (Section 7.4.11). 
18. For Part 1, only the first approximately 75 participants in Study Arm 1 and Study Arm 2 will have postbaseline scheduled blood draws; the 300 
participants in each of the expansion part of Study Arm 1 and Study Arm 2 may have an optional blood draw on Day 57. All participants in Study Arms 
3, 4, 5, 6 and 7 will have postbaseline blood draws on Day 57, Day 209 and Day 394. 
 
 

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Table 13: Schedule of Assessments for Placebo Recipient Cross-Over Vaccination with mRNA-1273 if any COVID-19 Vaccine 
is Authorized or Licensed for Participant’s Age Group1 
Abbreviations: AE = adverse event; AESI = adverse event of special interest; COVID-19 = coronavirus disease 2019; D = day; MAAE = medically attended 
adverse event; MIS-C = multisystem inflammatory syndrome in children; SAE = serious adverse event. 
1. Authorized or licensed in participant’s age group. 
2. Refer to Section 6.1.1 for individual participant criteria for delay of study vaccination. 
3. Pregnancy test prior to study injections on D1 and D29 will be a point-of-care urine test and will be performed if deemed appropriate by the investigator. At 
the discretion of the investigator, a pregnancy test either via blood or point-of-care urine test can be performed at any time during the study. 
Note: When a COVID-19 vaccine becomes available or another unblinding trigger is reached (Section 3.3) and a participant 
(parent/LAR) requests to unblind the following visits are expected: 
• Participant unblinds and has received mRNA-1273: 
− Participant remains in the study and continues with study visits as per SoA Table 12. 
− Cohort D participants: 
1. If they cross-over after Day 30, they will have already had this blood draw. 
2. If they cross-over between Dose 1 and Dose 2, they will NOT need to have the Day 30 blood draw. 
• Participant unblinds and has received placebo: 
− Participant will have 2 options: 
Schedule of Assessments for Placebo Recipient Cross-Over Vaccination 
Cross-
Over D1 
D29 
(+ 7)2 
D36 
(+ 3) 
D57 
(+ 7) 
Remainder 
of Study 
Visits 
Days Since Most Recent Injection  
 
28 
7 
28 
 
Study injection (including 30-minute post-dose observation period) 
X 
X 
 
 
 
Safety follow-up call 
 
 
X 
X 
 
Pregnancy test3 
X 
X 
 
 
 
Recording of unsolicited AEs 
X 
X 
X 
X 
 
Recording of MAAEs and concomitant medications relevant to or for the treatment 
of the MAAE 
X 
X 
X 
X 
X 
Recording of SAEs and concomitant medications relevant to or for the treatment of 
the SAE 
X 
X 
X 
X 
X 
Recording of AESIs (eg, MIS-C and myocarditis and/or pericarditis) 
X 
X 
X 
X 
X 

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1. Discontinue participating in the KidCOVE study 
2. Cross-over to mRNA-1273 (following Table 13- through Day 57 safety follow-up call) 
• A pregnancy test should be done for participants that are post-menarche prior to Dose 1 and Dose 2. 
• For the remainder of the study visits, as noted in Table 13, the participants will be followed for MAAEs, SAEs, 
and AESIs and concomitant medication relevant to, or for the treatment of MAAEs and SAEs. 
• Participants will continue being followed for safety, which includes COVID-19 surveillance, using electronic 
eDiaries and safety follow-up calls that will continue to trigger from the participant’s original (placebo) 
administration date. 
• Participants will have a clinic visit at study Day 209 from the original (placebo) administration date. At this visit, 
they will have a symptom-directed physical exam, if necessary, illness visit or convalescent visit work-up, if 
applicable, and a nasal swab. No blood samples will be required for this visit. 
• Participants will have a clinic visit at study Day 394 from the original (placebo) administration date. At this visit, 
they will have a symptom-directed physical exam, if necessary, illness visit or convalescent visit work-up, if 
applicable, and a nasal swab. 
In summary: No immunogenicity or serology samples will be required for cross-over participants unless they are part of a 
convalescent visit work-up or if they choose to receive a booster dose (as per Table 15, they will require a BD-Day1 baseline blood 
draw.) 
 
 

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Table 14: Phlebotomy Schedule for Serology, Biomarker Sample, and Cell-Mediated Immunity for Part 2 (Expansion) of the 
Study 
For participants that chose to receive a booster dose under protocol Amendment 7, please see Table 16 for the booster dose 
phlebotomy schedule. 
If Day 209/Day 394 blood draw is within 30 days of planned BD-Day 1, BD-Day 1 blood draw can be used for Day 209/Day 
394. 
Cohort 
Number of Subjects 
 
Study Visit Day 
D11,2 
D291 
D30 (+3)3 
D43 
D57 
D209 (+30 
days)4 
D394 (+30 
days)4 
 
Phlebotomy Schedule for Serology: To be Executed Within Age Group 
A 
First 176 (132 mRNA-1273: 44 
placebo) 
X 
X 
 
 
X 
 
 
B 
Next 176 (132 mRNA-1273: 44 
placebo) 
X 
 
 
 
X 
X 
 
C 
Next 176 (132 mRNA-1273: 44 
placebo) 
X 
 
 
 
X 
 
X 
D 
Remainder of the age group 
X 
 
X3 
 
 
 
 
 
Phlebotomy Schedule for Cell-Mediated Immunity: To be Executed Within Each Age Group at Selected VTEU Sites only 
E (CMI with 
exploratory 
serology) 
24 (18 mRNA-1273: 6 placebo) 
X 
 
 
X 
 
X 
X 
Abbreviations: BD = booster dose; CMI = cell-mediated immunity; D = day; mRNA = messenger RNA; VTEU = Vaccine and Treatment Evaluation Units. 
1. 
On Day 1, sample must be collected prior to randomization and dosing. On Day 29, sample must be collected prior to dosing. 
2. 
If a Day 1 (baseline) blood sample cannot be obtained in either Part 1 or Part 2, the participant will be considered either a screen failure due to inability 
to satisfy inclusion criterion 3 or could be scheduled for rescreening. Participants may be rescreened 1 time, either within same screening period for Part 
1 or Part 2 or in a new screening period for Part 2 if the initial screening was in Part 1. If the participant is rescreened and a blood sample still cannot be 
obtained, then he/she will be considered a screen failure due to inability to satisfy inclusion criterion 3. 
3. 
Serum sample from ~4 ml of blood only, to be stored for potential future use for biomarker assessment. 
4. 
If the participant decides to receive a booster dose, the BD1 blood draw (Table 15) can be used for Day 209 or Day 394 (Table 14). 
 
 

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Table 15: Schedule of Assessments for Optional Booster Doses with mRNA-1273 for Parts 1 and 2, Study Arms 1 Through 9 
under Protocol Amendment 7 
Visit Number 
BD-1 
BD-2 
BD-2A 
BD-3 
 
BD-4 
BD-5 
BD-6 
Type of Visit 
C 
SC 
C 
C 
SFU 
C 
SC 
C 
 
 
 
 
 
eDiary 
SC 
 
 
 
Study Visit Day 
BD-D11 
7 days 
after BD-
D1 (BD-
D8) 
14 days 
after BD-
D1 (Sub-
Cohort E 
only and 
optional) 
BD-D15 
BD-D29 
Every 4 weeks BD-
D43 – BD-D155 
Every 4 weeks BD-
D57– BD-D169 
BD-
D181 
 
270 days 
after BD-1 
(BD-D271) 
BD-
D366 
Window Allowance (Days) 
0  
+ 3 
+ 3 
-3/+14 
± 3 
± 3 
-3/+14 
+ 3 
-3/+14 
Days Since Most Recent Vaccination  
0 
7 
14 
28 
 
 
180 
270 
365 
Confirm informed consent /assent form 
booster addendum signing 
X 
 
 
 
 
 
 
 
 
Physical examination2 
X 
 
 
X 
 
 
X 
 
X 
Pregnancy testing3 
X 
 
 
 
 
 
 
 
 
Immunogenicity Assessment 
 
 
 
 
 
 
 
 
 
Pre-booster blood for immunologic 
analysis4 (or CMI with exploratory 
serology, as applicable) 5 
X 
 
 
 
 
 
 
 
 
Post-booster blood for immunologic 
analysis (or CMI with exploratory 
serology, as applicable) 5 
 
 
X 
X 
 
 
X 
 
X 
Dosing 
 
 
 
 
 
 
 
 
 
Study injection (including 30-minute 
post-dosing observation period6) 
X 
 
 
 
 
 
 
 
 
Unscheduled Visits7 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Nasal swab8 
X 
 
 
X 
 
 
X 
 
 
Safety Assessments 
 
 
 
 
 
 
 
 
 
Follow-up safety call9 
 
X 
 
 
 
 
 
X 
 

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Visit Number 
BD-1 
BD-2 
BD-2A 
BD-3 
 
BD-4 
BD-5 
BD-6 
Type of Visit 
C 
SC 
C 
C 
SFU 
C 
SC 
C 
 
 
 
 
 
eDiary 
SC 
 
 
 
Study Visit Day 
BD-D11 
7 days 
after BD-
D1 (BD-
D8) 
14 days 
after BD-
D1 (Sub-
Cohort E 
only and 
optional) 
BD-D15 
BD-D29 
Every 4 weeks BD-
D43 – BD-D155 
Every 4 weeks BD-
D57– BD-D169 
BD-
D181 
 
270 days 
after BD-1 
(BD-D271) 
BD-
D366 
Window Allowance (Days) 
0  
+ 3 
+ 3 
-3/+14 
± 3 
± 3 
-3/+14 
+ 3 
-3/+14 
Days Since Most Recent Vaccination  
0 
7 
14 
28 
 
 
180 
270 
365 
eDiary activation for recording solicited 
ARs (7 days)10 
X 
 
 
 
 
 
 
 
 
Review of eDiary data10 
 
X 
 
X 
 
 
 
 
 
Recording of unsolicited AEs, 
concomitant medications and nonstudy 
vaccinations 
X 
X 
X 
X 
 
 
 
 
 
Recording of AE leading to withdrawal 
and concomitant medications relevant for 
AE leading to withdrawal  
X 
X 
X 
X 
X 
X 
X 
X 
X 
Recording of SAEs, AESI and MAAEs 
and concomitant medications relevant to 
or for the treatment of the SAE, AESI or 
MAAE11 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Abbreviations: AE = adverse event; AESI = adverse event of special interest; AR = adverse reaction; BD = booster dose; C = clinic visit; CMI = cell-mediated 
immunity; COVID-19 = coronavirus disease 2019; D = day; eDiary = electronic diary; FDA = Food and Drug Administration; MAAE = medically attended 
AE; mRNA = messenger RNA; RT-PCR = reverse transcriptase polymerase chain reaction; SAE = serious adverse event; SARS-CoV-2 = severe acute 
respiratory syndrome coronavirus 2; SC = safety (phone) call; SFU = safety follow up. 
Note: In accordance with FDA Guidance on Conduct of Clinical Trials of Medical Products during COVID-19 Public Health Emergency (DHHS 2020), 
investigators may convert study site visits to home visits or telemedicine visits with the approval of the Sponsor. 
1. 
A BD may be administered to Part 1 participants (all ages) and 6 to < 12 year old Part 2 participants provided there are no current contraindications for 
further dosing. A participant who is currently in the Convalescent Period may come in for a BD-1 visit and receive a BD as long they are at least 
90 days from initial diagnosis of COVID-19. Applicable participants will be offered a booster at least 6 months (Participants in part 1 and participants 6 
to < 12 year old in Part 2) after Dose 2. 

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2. 
Symptom-directed physical examination will be performed at the BD-D1. On dosing day before injection, the arm receiving the injection should be 
examined and the associated lymph nodes should be evaluated. At visits BD-3 (BD-D29), BD-4 (BD-D181) and BD-6 (BD-D366), a symptom-directed 
physical examination may be performed at the discretion of the investigator. Any clinically significant finding identified during a study visit should be 
reported as a MAAE. An oral or tympanic temperature should be taken on the day of injection (BD-D1). Participants who are febrile (body temperature 
≥ 38.0°C/100.4°F) before dosing (BD-D1) must be rescheduled to receive the injection. Afebrile participants with minor illnesses can be vaccinated at 
the discretion of the investigator. 
3. 
Pregnancy test at BD-D1 before the booster dose injection will be a point-of-care urine test and will be performed if deemed appropriate by the 
investigator. At the discretion of the investigator, a pregnancy test either via blood or point-of-care urine test can be performed at any time during the 
study. 
4. 
Sample should be collected prior to dosing on BD-D1. 
5. 
Selected subgroups only; for details, see Table 16. Participants in sub-Cohort E original mRNA-1273 will have a blood sample for CMI and exploratory 
serology. 
6. 
Post-dosing, participants will have a 30-minute observation period. If any concerning symptoms occur, investigator may check vital signs during this 
period (however, no routine vital signs necessary after vaccination, except temperature as per 30-minute eDiary, if no concerning symptoms). 
7. 
An unscheduled visit may be prompted by reactogenicity issues or new or ongoing AEs. 
8. 
The nasal swab sample must be collected prior to injection at the BD-1 visit. 
9. 
Trained study personnel will call all participants to collect information relating to any unsolicited AEs, MAAEs (including any signs and symptoms of 
COVID-19), AESI, AEs leading to withdrawal, SAEs, information on concomitant medications associated with those events, and any nonstudy 
vaccinations. 
10. Age at time of enrollment determines which eDiary the participant will use. Diary entries will be recorded by the participant at approximately 
30 minutes after injection while at the study site with instruction provided by study staff. Study participants will continue to record entries in the eDiary 
each day after they leave the study site, preferably in the evening, on the day of injection and for 6 days following injection. If a solicited local or 
systemic AR continues beyond Day 7 after vaccination, the participant will be prompted to capture details of the solicited local or systemic AR in the 
eDiary until the AR resolves; capture of details of ARs in the eDiary should not exceed 28 days after vaccination. Adverse reactions recorded in 
eDiaries beyond Day 7 should be reviewed either via telephone call or at the following study visit. Review of eDiary will occur on BD-D8 and BD-D29. 
11. All concomitant medications relevant to or for the treatment of an SAE, AESI, or MAAE will be recorded from screening through the final visit. Non-
study COVID-19 vaccines will be recorded through EOS. 
 
 

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Table 16: Phlebotomy Schedule for Participants Opting for Booster Dose with mRNA-1273 under Amendment 7 by Part and 
Age Group 
BD-Day 1 
Post-booster Blood Samples 
Part 1 participants 
6 - < 12 years1 
Study Arm 1 
X 
BD-Day 29 for immunogenicity 
Study Arm 2 
X 
None 
2 to < 6 years1 
Study Arm 3 
X 
None 
Study Arm 4 
X 
None 
Study Arm 7 
X 
BD-Day 29 for immunogenicity 
6 months to < 2 years1 
Study Arm 5 
 
X 
BD-Day 29 for immunogenicity 
Part 2 participants 
Part 2, 6 to <12 years1,2 
 
Sub-Cohort A 
X 
None 
 
Sub-Cohort B 
X 
None 
 
Sub-Cohort C 
X 
BD-Day 29 for immunogenicity 
 
Sub-Cohort D 
X 
Enrolled 8/11/21-8/13/21 (~ 600) - BD-Day 29 
Enrolled 8/14/21 -8/17/21 (~600) - BD-Day 181 
Enrolled August 8/18-8/21 (~600) - BD-Day 366 
Enrolled after 8/21/21: None 
 
Sub-Cohort E3,5 
X 
(Optional BD-Day 154), BD-Day 181 
Abbreviations: BD = booster dose. 
1 Age at time of enrollment 
2 Participants who were 5 years old at enrollment but turned 6 years old prior to booster dose will only require a BD-Day1 blood draw. 
3 Participants who originally received placebo will not require any post-booster dose blood draws and will only have one blood draw on BD-Day 1 
for immunogenicity. 
4 BD-Day 15 is optional for participants in Sub-Cohort E. 
5 CMI samples and exploratory serology for participants originally receiving mRNA-1273.  
 
 

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Table 17: Schedule of Assessments for Part 3, Study Arm 14 
Visit Number 
0 
1 
2 
3 
4 
5 
 
6 
6A 
6B 
 
7 
8 
Type of Visit 
C 
C 
TMV 
C 
TMV 
C 
SFU 
C 
TMV 
C 
SFU 
C 
C 
Month Time Point 
 
M0 
 
M1 
 
M2 eDiary SC 
M5 
 
M6 
eDiary 
SC 
M11 M17 
Study Visit Day 
D-28 to D-1 
(Screening)1 
D1 (Baseline) 
D8 
D292 
D362 
D572, 3 
Every 4 weeks  
D71 – D1832, 4 
Every 4 weeks  
D85– D1972,5 
D149 (BD-D1) 
D156 (BD-D8) 
D177 (BD-D29) 
Every 4 weeks D191 
(BD-D43)– D303 
(BD-155)2,4 
Every 4 weeks D205 
(BD-D57)– D317 
BD-D169)2,5 
D329 (BD -D181)2, 5 
D514 (BD-D366) 
Window Allowance (Days) 
- 
- 
+ 3 
+ 7 
+ 3 
+ 7 
± 3 
± 3 
± 28 
+ 3 
+7 
± 3 
± 3 
± 14 ± 14 
Days Since Most Recent Injection 
- 
0 
7 
28 
7 
28 
- 
- 
120/0 127/7 148/28 
- 
- 
305/
180 
485/
365 
Informed consent/assent form, 
demographics, concomitant medications, 
medical history  
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Review of inclusion and exclusion 
criteria 
X 
X 
 
 
 
 
 
 
X 
 
 
 
 
 
 
Physical examination including body 
temperature, length/height, weight, and 
BMI6 
X 
X 
 
X 
 
X 
 
 
X 
 
 
 
 
X 
X 
Pregnancy test7 
X 
X 
 
X 
 
 
 
 
X 
 
 
 
 
 
 
Randomization  
 
X 
 
 
 
 
 
 
 
 
 
 
 
 
 
Study injection (including 30-minute 
post-dose observation period) 
 
X 
 
X 
 
 
 
 
X 
 
 
 
 
 
 
Blood sample for vaccine 
immunogenicity (Part 3)8,9 
 
X 
 
 
 
X 
 
 
X9 
 
X 
 
 
X10 
X11 
Nasal swab sample for SARS-CoV-212 
 
X 
 
X 
 
X 
 
 
X 
 
X 
 
 
X 
X 
Unscheduled visit13 
 
 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
eDiary activation for recording solicited 
ARs (7 days)15 
 
X 
 
X 
 
 
 
 
X 
 
 
 
 
 
 
Review of eDiary data 
 
 
X 
 
X 
 
 
 
 
X 
 
 
 
 
 
Follow-up safety telephone calls16 
 
 
 
 
 
 
 
X 
 
 
 
 
X 
 
 
Recording of unsolicited AEs 
 
X 
X 
X 
X 
X 
 
 
X 
X 
X 
 
 
 
 

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Visit Number 
0 
1 
2 
3 
4 
5 
 
6 
6A 
6B 
 
7 
8 
Type of Visit 
C 
C 
TMV 
C 
TMV 
C 
SFU 
C 
TMV 
C 
SFU 
C 
C 
Month Time Point 
 
M0 
 
M1 
 
M2 eDiary SC 
M5 
 
M6 
eDiary 
SC 
M11 M17 
Study Visit Day 
D-28 to D-1 
(Screening)1 
D1 (Baseline) 
D8 
D292 
D362 
D572, 3 
Every 4 weeks  
D71 – D1832, 4 
Every 4 weeks  
D85– D1972,5 
D149 (BD-D1) 
D156 (BD-D8) 
D177 (BD-D29) 
Every 4 weeks D191 
(BD-D43)– D303 
(BD-155)2,4 
Every 4 weeks D205 
(BD-D57)– D317 
BD-D169)2,5 
D329 (BD -D181)2, 5 
D514 (BD-D366) 
Window Allowance (Days) 
- 
- 
+ 3 
+ 7 
+ 3 
+ 7 
± 3 
± 3 
± 28 
+ 3 
+7 
± 3 
± 3 
± 14 ± 14 
Days Since Most Recent Injection 
- 
0 
7 
28 
7 
28 
- 
- 
120/0 127/7 148/28 
- 
- 
305/
180 
485/
365 
Recording of MAAEs, SAEs, and AESIs 
(eg, MIS-C, myocarditis/pericarditis) and 
concomitant medications and procedures 
relevant to or for the treatment of the 
MAAE, AESI and SAE17 
 
X 
X 
X 
X 
X 
X 
 
X 
X 
X 
X 
 
X 
X 
Recording of concomitant medications 
and procedures and nonstudy 
vaccinations18 
 
X 
X 
X 
X 
X 
 
 
X 
X 
X 
 
 
 
 
Study completion 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
X 
Abbreviations: AE = adverse event; AESI = adverse event of special interest; AR = adverse reaction; BD = booster (third) dose; BMI = body mass index; 
C = clinic visit; COVID-19 = coronavirus disease 2019; D = day; eCRF = electronic case report form; EDC = electronic data capture; eDiary = electronic diary; 
FDA = Food and Drug Administration; IP = investigational product; IRB = institutional review board; LAR = legally authorized representative; M = month; 
MAAE = medically attended adverse event; MIS-C = multisystem inflammatory syndrome in children; RT-PCR = reverse transcriptase polymerase chain 
reaction; SAE = serious adverse event; SARS-CoV-2 = severe acute respiratory syndrome coronavirus 2; SC = safety (telephone) call; SFU = safety follow-up; 
TMV = telemedicine visit. 
Note: In accordance with FDA Guidance on Conduct of Clinical Trials of Medical Products during COVID-19 Public Health Emergency (FDA March 2020), 
investigators may convert study site visits to home visits or telemedicine visits (with the exception of Screening, Day 1, Day 29, and Day 149) with the 
approval of the Sponsor. 
1. 
Screening Visit and Day 1 may be combined on the same day. Additionally, the Screening Visit may be performed over multiple visits if performed 
within the 28-day screening window. 
2. 
If the visit for the second dose (Day 29) is disrupted and cannot be completed at Day 29 (+7 days) as a result of the COVID-19 pandemic (self-
quarantine or disruption of study site activities following business continuity plans and/or local government mandates for “stay at home” or “shelter in 
place”), the visit window may be extended to Day 29 + 21 days. When the extended visit window is used, the remaining study visits should be 

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rescheduled to follow the intervisit interval from the actual date of the second dose. Refer to Section 6.1.1 for individual participant criteria for delay of 
study vaccination. 
3. 
All scheduled study visits should be completed within the respective visit windows. If the participant is not able to attend a study site visit as a result of 
the COVID-19 pandemic (self-quarantine or disruption of study site activities following business continuity plans and/or local government mandates for 
“stay at home” or “shelter in place”), a telemedicine visit should be conducted in place of the study site visit. The telemedicine visit should encompass 
all scheduled visit assessments that can be completed remotely, such as assessment for AEs and concomitant medications (eg, as defined in scheduled 
safety telephone calls). Home visits will be permitted for all nondosing visits, with the exception of Screening, if a participant cannot visit the study site 
as a result of the COVID-19 pandemic. Home visits must be permitted by the study site IRB and the participant’s parent(s)/LAR(s) via informed consent 
and have prior approval from the Sponsor (or its designee). 
4. 
Safety follow-up via an eDiary questionnaire will be performed every 4 weeks from Day 71 to Day 183 and again from Day 191 to Day 303. 
5. 
Safety follow-up via a safety telephone call will be performed every 4 weeks from Day 85 to Day 197 and again from Day 205 to Day 317. 
6. 
A full physical examination, including body temperature (oral [for participants > 4 years of age] or tympanic [for participants ≤ 4 years of age]), 
length/height, and weight, will be performed at the Screening Visit or on Day 1. Symptom-directed physical examination will be performed on Day 1, 
Day 29, Day 57, Day 149, Day 329, and Day 514 and may be performed at other time points at the discretion of the investigator. Body mass index will 
be calculated only at Screening Visit. Body temperature (oral/tympanic) should be measured on each injection day prior to injection. On each injection 
day before injection and again 7 days after injection, the injection site should be examined. Any clinically significant finding identified during a study 
visit should be reported as an MAAE. Participants who are febrile (body temperature ≥ 38.0°C/≥ 100.4°F) before injection on Day 1 Day 29, or Day 149 
must have the visit rescheduled within the relevant visit window to receive the injection. Afebrile participants with minor illnesses may be injected at 
the discretion of the investigator. 
7. 
Pregnancy test at Screening and Day 1 and before the second and third study injection will be a point-of-care urine test and will be performed if deemed 
appropriate by the investigator. At the discretion of the investigator, a pregnancy test either via blood or point-of-care urine test can be performed at any 
time during the study. 
8. 
On Day 1, sample must be collected prior to randomization and dosing. If a Day 1 (baseline) blood sample cannot be obtained in Part 3, the participant 
will be considered either a screen failure due to inability to satisfy inclusion criterion 3 or could be scheduled for rescreening. Participants may be 
rescreened 1 time. If the participant is rescreened and a blood sample still cannot be obtained, then he/she will be considered a screen failure due to 
inability to satisfy inclusion criterion 3. 
9. 
On Day 149, sample must be collected prior to dosing. 
10. Sub-Cohort F only, see Table 18 for details. 
11. Sub-Cohort G only, see Table 18 for details. 
12. The nasal swab sample (collected before dosing on injection day) will be used to ascertain the presence of SARS-CoV-2 via RT-PCR. 
13. An unscheduled visit may be prompted by reactogenicity issues, or new or ongoing AEs. 
14. A convalescent visit may be scheduled approximately 28 days (+7 days) after diagnosis of COVID-19 if there are any doubts about initial diagnosis (at 
investigator’s discretion). At this visit, a blood sample for potential immunologic assessment of SARS-CoV-2 infection will be collected. 
15. At each injection visit, participants’ parent(s)/LAR(s) will record data into the eDiary starting approximately 30 minutes after injection under the 
supervision of the study site staff to ensure successful entry of assessment. Participants’ parent(s)/LAR(s) will continue to record entries in the eDiary 
after they leave the study site, preferably in the evening and at the same time each day, on the day of injection and for 6 days following injection. If a 
solicited local or systemic AR continues beyond Day 7 after vaccination, the participant’s parent(s)/LAR(s) will be prompted to capture details of the 
solicited local or systemic AR in the eDiary until the AR is resolved or the next IP injection occurs, whichever occurs first. Capturing details of ARs in 
the eDiary should not exceed 28 days after each vaccination. Adverse reactions recorded in eDiaries beyond Day 7 should be reviewed by the study site 
staff either during the next scheduled telephone call or at the next study site visit. 

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16. Trained study site personnel will call all participants to collect information relating to any MAAEs, SAEs, AEs leading to study withdrawal and 
information on concomitant medications associated with those events and any nonstudy vaccinations. In addition, study personnel will collect 
information on known participant exposure to someone with known COVID-19 or SARS-CoV-2 infection and on any COVID-19 symptoms the 
participant may experience. 
17. All concomitant medications and procedures and nonstudy vaccinations will be recorded through 28 days after each injection; all concomitant 
medications relevant to or for the treatment of an SAE, AESI or MAAE will be recorded from Day 1 through the final visit (Day 514). 
18. In addition to MIS-C and myocarditis and/or pericarditis, a list of AESIs pertinent to this study may be referenced in the list of AESIs that is maintained 
by the Sponsor and provided to each investigator. All SAEs and AESIs will be reported to the Sponsor or designee immediately and in all circumstances 
within 24 hours of becoming aware of the event via the EDC system. If a site receives a report of a new SAE or AESI from a study participant or 
receives updated data on a previously reported SAE or AESI and the eCRF has been taken offline, then the site can report this information on a paper 
SAE or AESI form using the SAE Mailbox, the SAE Hotline, or the SAE Fax line (Section 7.4.11). 

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Table 18: Phlebotomy Schedule for Serology for Part 3 
Sub-Cohort  
Number of Subjects 
Study Visit Day 
D11,2 
D57 
D1491 
D177 
D329 
D514 
F 
First 150 participants 
X 
X 
X 
X 
X 
 
G 
Next 150 participants 
X 
X 
X 
X 
 
X 
Abbreviations: D = day. 
1. On Day 1, sample must be collected prior to randomization and dosing. On Day 149, sample must be collected prior to dosing. 
Note: If a Day 1 (baseline) blood sample cannot be obtained in Part 3, the participant will be considered either a screen failure due to inability to satisfy inclusion 
criterion 3 or could be scheduled for rescreening. Participants may be rescreened 1 time. If the participant is rescreened and a blood sample still cannot be 
obtained, then he/she will be considered a screen failure due to inability to satisfy inclusion criterion 3. 
Table 19: Schedule of Assessments for Optional Booster Doses with mRNA-1273.214 for Previously Unboosted Participants 
from Part 1 and Part 2 under Protocol Amendment 9 
Visit Number 
BD-1 
BD-2 
BD-3 
SFU 
BD-4 
Type of Visit 
C 
SC 
C 
 
C 
 
 
 
 
SC 
 
Study Visit Day 
BD-D11 
7 days after BD-D1 
(BD-D8) 
BD-D29 
Every 4 
weeks BD-
D57– BD-
D169 
BD-D181 (EOS) 
Window Allowance (Days) 
0  
+ 3 
-3/+14 
± 3 
-3/+14 
Days Since Most Recent Vaccination  
0 
7 
28 
 
180 
Confirm informed consent /assent form booster 
addendum signing 
X 
 
 
 
 
Physical examination2 
X 
 
X 
 
X 
Pregnancy testing3 
X 
 
 
 
 
Immunogenicity Assessment 
 
 
 
 
 
Pre-booster blood for immunologic analysis4  
X 
 
 
 
 
Dosing 
 
 
 
 
 

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Visit Number 
BD-1 
BD-2 
BD-3 
SFU 
BD-4 
Type of Visit 
C 
SC 
C 
 
C 
 
 
 
 
SC 
 
Study Visit Day 
BD-D11 
7 days after BD-D1 
(BD-D8) 
BD-D29 
Every 4 
weeks BD-
D57– BD-
D169 
BD-D181 (EOS) 
Window Allowance (Days) 
0  
+ 3 
-3/+14 
± 3 
-3/+14 
Days Since Most Recent Vaccination  
0 
7 
28 
 
180 
Study injection (including 30-minute post-dosing 
observation period5) 
X 
 
 
 
 
Unscheduled visits6 
X 
X 
X 
X 
X 
Nasal swab7 
X 
 
X 
 
X 
Safety Assessments 
 
 
 
 
 
Follow-up safety call8 
 
X 
 
 
 
Recording of AE leading to withdrawal and 
concomitant medications relevant for AE leading to 
withdrawal  
X 
X 
X 
X 
X 
Recording of SAEs, AESI and MAAEs and 
concomitant medications relevant to or for the 
treatment of the SAE, AESI or MAAE9 
X 
X 
X 
X 
X 
 
Abbreviations: AE = adverse event; AESI = adverse event of special interest; AR = adverse reaction; BD = booster dose; C = clinic visit; CMI = cell-
mediated immunity; COVID-19 = coronavirus disease 2019; D = day; eDiary = electronic diary; FDA = Food and Drug Administration; MAAE = medically 
attended AE; mRNA = messenger RNA; RT-PCR = reverse transcriptase polymerase chain reaction; SAE = serious adverse event; SARS-CoV-2 = severe 
acute respiratory syndrome coronavirus 2; SC = safety (phone) call; SFU = safety follow up. 
Note: In accordance with FDA Guidance on Conduct of Clinical Trials of Medical Products during COVID-19 Public Health Emergency (DHHS 2020), 
investigators may convert study site visits to home visits or telemedicine visits with the approval of the Sponsor. 
1. 
A BD may be administered to all Part 2 participants provided there are no current contraindications for further dosing and have not received any booster 
doses outside of the trial. A participant who is currently in the Convalescent Period may come in for a BD-1 visit and receive a BD as long they are at 
least 90 days from initial diagnosis of COVID-19. Applicable participants will be offered a booster at least 3 months after Dose 2. 
2. 
Symptom-directed physical examination will be performed at the BD-D1. On dosing day before injection, the arm receiving the injection should be 
examined and the associated lymph nodes should be evaluated. At visits BD-3 (BD-D29), BD-4 (BD-D181) and BD-6 (BD-D366), a symptom-directed 

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physical examination may be performed at the discretion of the investigator. Any clinically significant finding identified during a study visit should be 
reported as a MAAE. An oral or tympanic temperature should be taken on the day of injection (BD-D1) prior to dosing. Participants who are febrile 
(body temperature ≥ 38.0°C/100.4°F) before dosing (BD-D1) must be rescheduled to receive the injection. Afebrile participants with minor illnesses can 
be vaccinated at the discretion of the investigator. 
3. 
Pregnancy test at BD-D1 before the booster dose injection will be a point-of-care urine test and will be performed if deemed appropriate by the 
investigator. At the discretion of the investigator, a pregnancy test either via blood or point-of-care urine test can be performed at any time during the 
study. 
4. 
Sample should be collected prior to dosing on BD-D1. 
5. 
Post-dosing, participants will have a 30-minute observation period. If any concerning symptoms occur, investigator may check vital signs during this 
period (however, no routine vital signs necessary after vaccination if no concerning symptoms). 
6. 
An unscheduled visit may be prompted by reactogenicity issues, or new or ongoing AEs. 
7. 
The nasal swab sample must be collected prior to injection at the BD-1 visit. 
8. 
Trained study personnel will call all participants to collect information relating to any MAAEs (including any signs and symptoms of COVID-19), 
AESI, AEs leading to withdrawal, SAEs, information on concomitant medications associated with those events, and any non-study vaccinations. Any 
solicited AR or AE that meets any of the following criteria must be entered into the participant’s eCRF:1) An Event, including local or systemic AR, 
that results in a visit to a healthcare practitioner (HCP) (MAAE). 2) An Event, including local or systemic AR, leading to the participant withdrawing 
from the study or the participant being withdrawn from the study by the Investigator (AE leading to withdrawal) 3) An Event, including local or 
systemic AR, that otherwise meets the definition of an SAE. 4) Any AESI. 
9. 
All concomitant medications relevant to or for the treatment of an SAE, AESI, or MAAE will be recorded from screening through the final visit. Non-
study COVID-19 vaccines will be recorded through EOS. 
 
 

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10.2 APPENDIX 2: Study Governance Considerations 
10.2.1 Regulatory and Ethical Considerations 
This study will be conducted in accordance with the protocol and with the following: 
Consensus ethical principles derived from international guidelines, including the Declaration of 
Helsinki and Council for International Organizations of Medical Sciences International Ethical 
Guidelines. 
Applicable ICH GCP guidelines. 
Applicable laws and regulatory requirements. 
The protocol, protocol amendments, ICF, IB, and other relevant documents (eg, advertisements) 
must be submitted to an IRB by the investigator and reviewed and approved by the IRB before 
the study is initiated. 
Any amendments to the protocol will require IRB approval before implementation of changes 
made to the study design, except for changes necessary to eliminate an immediate hazard to 
study participants. 
The investigator will be responsible for the following: 
Providing written summaries of the status of the study to the IRB annually or more frequently in 
accordance with the requirements, policies, and procedures established by the IRB 
Notifying the IRB of SAEs or other significant safety findings as required by IRB procedures 
Providing oversight of the conduct of the study at the site and adherence to requirements of 21 
CFR, ICH guidelines, the IRB, European regulation 536/2014 for clinical studies (if applicable), 
and all other applicable local regulations. 
10.2.2 Study Monitoring 
Before an investigational site can enter a participant into the study, a representative of the 
Sponsor or its representatives will visit the investigational study site to do the following: 
Determine the adequacy of the facilities. 
Discuss with the investigator(s) and other personnel their responsibilities with regard to protocol 
adherence, and the responsibilities of the Sponsor or its representatives. This will be documented 
in a clinical study agreement between the Sponsor, the designated CRO, and the investigator. 
According to ICH GCP guidelines, the Sponsor of the study is responsible for ensuring the 
proper conduct of the study with regard to protocol adherence and validity of data recorded on 
the eCRFs. The study monitor’s duties are to aid the investigator and the Sponsor in the 

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maintenance of complete, accurate, legible, well-organized, and easily retrievable data. The 
study monitor will advise the investigator of the regulatory necessity for study-related 
monitoring, audits, IRB review, and inspection by providing direct access to the source 
data/documents. In addition, the study monitor will explain to and interpret for the investigator 
all regulations applicable to the clinical evaluation of an IP as documented in ICH guidelines. 
It is the study monitor’s responsibility to inspect the eCRFs and source documentation 
throughout the study to protect the rights of the participants; to verify adherence to the protocol; 
to verify the completeness, accuracy, and consistency of the data; and to confirm adherence of 
study conduct to any local regulations. Details will be outlined in the Clinical Monitoring Plan. 
During the study, a monitor from the Sponsor or a representative will have regular contacts with 
the investigational site, for the following purposes: 
Provide information and support to the investigator(s). 
Confirm that facilities remain acceptable. 
Confirm that the investigational team is adhering to the protocol, that the data are being 
accurately recorded in the eCRFs, and that IP accountability checks are being performed. 
Perform source data verification. This includes a comparison of the data in the eCRFs with the 
participant’s medical records at the hospital or practice and other records relevant to the study. 
This will require direct access to all original records for each participant (eg, clinical charts or 
electronic medical record system). 
Record and report any protocol deviations not previously sent. 
Confirm that AEs and SAEs have been properly documented on eCRFs, that any SAEs have 
been forwarded to the SAE Hotline, and that those SAEs that meet criteria for reporting have 
been forwarded to the IRB. 
The monitor will be available between visits if the investigator(s) or other staff need information 
or advice. 
10.2.3 Audits and Inspections 
The Sponsor, their designee(s), the IRB, or regulatory authorities will be allowed to conduct 
study site visits to the investigational facilities for the purpose of monitoring or inspecting any 
aspect of the study. The investigator agrees to allow the Sponsor, their designee(s), the IRB, or 
regulatory authorities to inspect the IP storage area, IP stocks, IP records, participant charts and 
study source documents, and other records relative to study conduct. 
Authorized representatives of the Sponsor, a regulatory authority, and any IRB may visit the 
study site to perform audits or inspections, including source data verification. The purpose of a 

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Sponsor audit or inspection is to systematically and independently examine all study-related 
activities and documents to determine whether these activities were conducted and data were 
recorded, analyzed, and accurately reported according to the protocol, ICH E6(R2) GCP, and any 
applicable regulatory requirements. The investigator should contact the Sponsor immediately if 
contacted by a regulatory agency about an inspection. 
The principal investigator must obtain IRB approval for the investigation. Initial IRB approval, 
and all materials approved by the IRB for this study, including the informed consent/assent 
forms and recruitment materials, must be maintained by the investigator and made available for 
inspection. 
10.2.4 Financial Disclosure 
The investigator is required to provide financial disclosure information to allow the Sponsor to 
submit the complete and accurate certification or disclosure statements required under 21 CFR 54. 
In addition, the investigator must provide the Sponsor with a commitment to promptly update 
this information if any relevant changes occur during the course of the investigation and for 
1 year following the completion of the study. 
The Sponsor, the CRO, and the study site are not financially responsible for further testing or 
treatment of any medical condition that may be detected during the screening process. In addition, 
in the absence of specific arrangements, the Sponsor, the CRO, and the study site are not 
financially responsible for further treatment of the disease under study. 
10.2.5 Recruitment Procedures 
Advertisements to be used for the recruitment of study participants and any other written 
information regarding this study to be provided to the participant’s parent(s)/LAR(s) should be 
submitted to the Sponsor for approval. All documents must be approved by the IRB. 
10.2.6 Informed Consent/Assent Process 
The informed consent and assent document(s) must meet the requirements of 21 CFR 50, local 
regulations, ICH guidelines, the Health Insurance Portability and Accountability Act, where 
applicable, and the IRB or study site. All consent/assent documents will be approved by the 
appropriate IRB. The actual ICF used at each study site may differ, depending on local 
regulations and IRB requirements. However, all versions of the ICF must contain the standard 
information found in the sample ICF provided by the Sponsor. Any change to the content of the 
ICF must be approved by the Sponsor and the IRB prior to the ICF being used. 
If new information becomes available that may be relevant to the participant’s willingness to 
continue participation in the study, this will be communicated to them in a timely manner. Such 
information will be provided via a revised ICF or an addendum to the original ICF. 

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The investigator or his/her representative will explain the nature of the study to the participant’s 
parent(s)/LAR(s) and answer all questions regarding the study. 
The investigator is responsible for ensuring that the participant’s parent(s)/LAR(s) fully 
understands the nature and purpose of the study. Information should be given in both oral and 
written form whenever possible. 
No participant should be obliged to participate in the study. The participant’s parent(s)/LAR(s) 
must be informed that participation is voluntary. The participant’s relatives, guardians, or (if 
applicable) LARs must be given ample opportunity to inquire about details of the study. The 
information must make clear that refusal to participate in the study or withdrawal from the study 
at any stage is without any prejudice to the participant’s subsequent care. 
The participant’s parent(s)/LAR(s) must be allowed sufficient time to decide whether they wish 
to let their child participate in the study. 
The participant’s parent(s)/LAR(s) must be made aware of, and give consent to, direct access to 
participant’s source medical records by study monitors, auditors, the IRB, and regulatory 
authorities. The participant’s parent(s)/LAR(s) should be informed that such access will not 
violate participant confidentiality or any applicable regulations. The participant’s 
parent(s)/LAR(s) should also be informed that he/she is authorizing such access by signing the 
ICF. 
A copy of the ICF(s) must be provided to the participants’ parent(s)/LAR(s). 
Parent(s)/LAR(s) of a participant who is rescreened (allowed once) are not required to sign 
another ICF if the rescreening occurs within 28 days from the previous ICF signature date 
(within the initial screening period). 
The ICF will also explain that excess serum from immunogenicity testing may be used for future 
research, which may be performed at the discretion of the Sponsor to further characterize the 
immune response to SARS-CoV-2, additional assay development, and the immune response 
across CoVs. 
10.2.7 Protocol Amendments 
No change or amendment to this protocol may be made by the investigator or the Sponsor after 
the protocol has been agreed to and signed by all parties unless such change(s) or amendment(s) 
has (have) been agreed upon by the investigator or the Sponsor. Any change agreed upon will be 
recorded in writing, and the written amendment will be signed by the investigator and the 
Sponsor. Approval of the IRB is required prior to the implementation of an amendment, unless 
overriding safety reasons warrant immediate action, in which case the IRB(s) will be promptly 
notified. 

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Any modifications to the protocol or the ICF that may impact the conduct of the study or 
potential benefit of the study or may affect participant safety, including changes of study 
objectives, study design, participant population, sample sizes, study procedures, or significant 
administrative aspects, will require a formal amendment to the protocol. Such an amendment 
will be released by the Sponsor, agreed to by the investigator(s), and approved by the relevant 
IRB(s) prior to implementation. A signed and dated statement that the protocol, any subsequent 
relevant amended documents, and the ICF have been approved by relevant IRB(s) must be 
provided to the Sponsor before the study is initiated. 
Administrative changes of the protocol are minor corrections and/or clarifications that have no 
effect on the way the study is to be conducted. These administrative changes will be released by 
the Sponsor, agreed to by the investigators, and notified to the IRB(s). 
10.2.8 Protocol Deviations 
The noncompliance may be on the part of the participant, the investigator, or the study site staff. 
As a result of protocol deviations, corrective actions are to be developed by the study site and 
implemented promptly. 
It is the responsibility of the study site investigator to use continuous vigilance to identify and 
report protocol deviations to the Sponsor or its designee. All protocol deviations must be 
addressed in study source documents and reported to study monitor. Protocol deviations must be 
sent to the reviewing IRB per their policies. The study site investigator is responsible for 
knowing and adhering to the reviewing IRB requirements. 
10.2.9 Data Protection 
Participants will be assigned a unique identifier by the Sponsor. Any participant records or 
datasets that are transferred to the Sponsor will contain the identifier only; participant names or 
any information that would make the participant identifiable will not be transferred. 
The participant’s parent(s)/LAR(s) must be informed that the participant’s personal study-related 
data will be used by the Sponsor in accordance with local data protection law. The level of 
disclosure must also be explained to the participant’s parent(s)/LAR(s). 
The participant’s parent(s)/LAR(s) must be informed that the participant’s medical records may 
be examined by clinical quality assurance (QA) auditors or other authorized personnel appointed 
by the Sponsor, by appropriate IRB members, and by inspectors from regulatory authorities. 
Individual participant medical information obtained as a result of this study is considered 
confidential, and disclosure to third parties is prohibited. Information will be accessible to 
authorized parties or personnel only. Medical information may be given to the participant’s 
physician or to other appropriate medical personnel responsible for the participant’s well-being. 

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Each participant’s parent(s)/LAR(s) will be asked to complete a form allowing the investigator to 
notify the participant’s primary health care provider of his/her participation in this study. 
All laboratory specimens, evaluation forms, reports, and other records will be identified in a 
manner designed to maintain participant confidentiality. All records will be kept in a secure 
storage area with limited access. Clinical information will not be released without the written 
permission of the participant’s parent(s)/LAR(s), except as necessary for monitoring and 
auditing by the Sponsor, its designee, the relevant regulatory authority, or the IRB. 
The investigator and all employees and coworkers involved with this study may not disclose or 
use for any purpose other than performance of the study, any data, record, or other unpublished 
confidential information disclosed to those individuals for the purpose of the study. Prior written 
agreement from the Sponsor or its designee must be obtained for the disclosure of any 
confidential information to other parties. 
10.2.10 Sample Retention and Future Biomedical Research 
The retention period of laboratory samples will be 20 years, or as permitted by local regulations, 
to address further scientific questions related to mRNA-1273 or anti-respiratory virus immune 
response. In addition, identifiable samples can be destroyed at any time at the request of the 
participant. During the study, or during the retention period, in addition to the analysis outlined 
in the study endpoints, exploratory analysis may be conducted using other Ab-based 
methodologies on any remaining blood or serum samples, including samples from participants 
who are screened but are not subsequently enrolled and samples collected and stored from 
Cohort D in Part 2. These analyses will extend the search for other potentially relevant 
biomarkers to investigate the effect of mRNA-1273, as well as to determine how changes in 
biomarkers may relate to exposure and clinical outcomes. A decision to perform such 
exploratory research may arise from new scientific findings related to the drug class or disease, 
as well as reagent and assay availability. 
 
 
 
 
 
 
 
 

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10.2.11 Dissemination of Clinical Study Data 
The Sponsor shares information about clinical trials and results on publicly accessible websites, 
based on international and local legal and regulatory requirements and other clinical trial 
disclosure commitments established by pharmaceutical industry associations. These websites 
include clinicaltrials.gov, EU clinical trial register (eu.ctr), and some national registries. 
In addition, results from clinical trials are required to be submitted to peer-reviewed journals 
following internal company review for accuracy, fair balance, and intellectual property. For 
those journals that request sharing of the analyzable data sets that are reported in the publication, 
interested researchers are directed to submit their request to clinicalstudydatarequest.com. 
Individual participant data and supporting clinical documents are available for request at 
clinicalstudydatarequest.com. While making information available, the privacy of participants in 
clinical studies sponsored by the Sponsor is ensured. Details on data sharing criteria and the 
process for requesting access can be found at this web address: clinicalstudydatarequest.com. 
10.2.12 Data Quality Assurance and Quality Control 
Data collection is the responsibility of the clinical study staff at the study site under the 
supervision of the study site investigator. The investigator is responsible for ensuring the 
accuracy, completeness, legibility, and timeliness of the data reported. 
• All participant data relating to the study will be recorded in the eCRF unless transmitted 
to the Sponsor or designee electronically (eg, laboratory data). The investigator is 
responsible for verifying that data entries are accurate and correct by physically or 
electronically signing the eCRF. 
• The investigator must maintain accurate documentation (source data) that supports the 
information entered in the eCRF. 
• The investigator must permit study-related monitoring, audits, IRB review, and 
regulatory agency inspections and provide direct access to source data documents. 
• Monitoring details describing strategy (eg, risk-based initiatives in operations and quality 
such as Risk Management and Mitigation Strategies and Analytical Risk-Based 
Monitoring), methods, responsibilities and requirements, including handling of 
noncompliance issues and monitoring techniques (central, remote, or onsite monitoring) 
are provided in the Clinical Monitoring Plan. 
• The Sponsor or designee is responsible for the data management of this study, including 
quality checks of the data. 
• The Sponsor assumes accountability for actions delegated to other individuals (eg, CRO). 

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• Study monitors will perform ongoing source data verification to confirm that data entered 
into the CRF by authorized study site personnel are accurate, complete, and verifiable 
from source documents; that the safety and rights of participants are being protected; and 
that the study is being conducted in accordance with the currently approved protocol and 
any other study agreements, ICH GCP, and all applicable regulatory requirements. 
• Records and documents, including signed ICFs, pertaining to the conduct of this study 
must be retained by the investigator for a period of at least 2 years after the last marketing 
application approval or, if not approved, 2 years following the discontinuance of the test 
article for investigation. If this requirement differs from any local regulations, the local 
regulations will take precedence unless the local retention policy is less than 2 years. No 
records may be destroyed during the retention period without the written approval of the 
Sponsor. No records may be transferred to another location or party without written 
notification to the Sponsor. 
Quality assurance includes all the planned and systematic actions that are established to ensure 
that the clinical study is performed and the data are generated, documented (recorded), and 
reported according to ICH GCP and local/regional regulatory standards. 
A QA representative from the Sponsor or a qualified designee, who is independent of and 
separated from routine monitoring, may periodically arrange inspections/audits of the clinical 
study by reviewing the data obtained and procedural aspects. These inspections may include 
on-site inspections/audits and source data checks. Direct access to source documents is required 
for the purpose of these periodic inspections/audits. 
10.2.13 Data Collection and Management 
This study will be conducted in compliance with ICH CGP guidelines. This study will also be 
conducted in accordance with the most recent version of the Declaration of Helsinki. 
This study will use electronic data collection to collect data directly from the study site using 
eCRFs. The investigator is responsible for ensuring that all sections of each eCRF are completed 
promptly and correctly and that entries can be verified against any source data. 
Study monitors will perform source document verification to identify inconsistencies between 
the eCRFs and source documents. Discrepancies will be resolved in accordance with the 
principles of GCP. Detailed study monitoring procedures are provided in the Clinical Monitoring 
Plan. 
Adverse events will be coded with MedDRA. Concomitant medications will be coded using 
WHO - Drug Dictionary. 
 

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10.2.14 Source Documents 
Source documents are original documents or certified copies, and include, but are not limited to, 
eDiaries, medical and hospital records, screening logs, ICFs, telephone contact logs, and 
worksheets. Source documents provide evidence for the existence of the participant and 
substantiate the integrity of the data collected. Source documents are filed at the investigator’s 
study site. 
Data reported on the CRF or entered in the eCRF that are transcribed from source documents 
must be consistent with the source documents or the discrepancies must be explained. The 
investigator may need to request previous medical records or transfer records, depending on the 
study. Also, current medical records must be available. 
The Sponsor or its designee requires that the investigator prepare and maintain adequate and 
accurate records for each participant treated with the IP. Source documents such as any hospital, 
clinic, or office charts, and the signed ICFs are to be included in the investigator’s files with the 
participant’s study records. 
10.2.15 Retention of Records 
The principal investigator must maintain all documentation relating to the study for a period of at 
least 2 years after the last marketing application approval or, if not approved, 2 years following 
the discontinuance of the test article for investigation. If this requirement differs from any local 
regulations, the local regulations will take precedence unless the local retention policy is 
> 2 years. 
If it becomes necessary for the Sponsor or the regulatory authority to review any documentation 
relating to the study, the investigator must permit access to such records. No records will be 
destroyed without the written consent of the Sponsor, if applicable. It is the responsibility of the 
Sponsor to inform the investigator when these documents no longer need to be retained. 
10.2.16 Study and Site Closure 
If the study is prematurely terminated or suspended, the Sponsor shall promptly inform the 
investigators, the IRBs, the regulatory authorities, and any CRO(s) used in the study of the 
reason for termination or suspension, as specified by the applicable regulatory requirements. The 
investigator shall promptly inform the participants and should ensure appropriate participant 
therapy and/or follow-up. 
The Sponsor or designee reserves the right to close the study site or terminate the study at any 
time for any reason at the sole discretion of the Sponsor. 
The investigator may initiate study site closure at any time, provided there is reasonable cause 
and sufficient notice is given in advance of the intended termination. 

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Reasons for the early closure of a study site by the Sponsor or investigator may include but are 
not limited to the following: 
• Continuation of the study represents a significant medical risk to participants 
• Failure of the investigator to comply with the protocol, the requirements of the IRB or 
local health authorities, the Sponsor’s procedures, or GCP guidelines 
• Inadequate recruitment of participants by the investigator 
• Discontinuation of further mRNA-1273 development 
Study sites will be closed upon study completion. A study site is considered closed when all 
required documents and study supplies have been collected and a study site closure visit has been 
performed. 
10.2.17 Publication Policy 
The results of this study may be published or presented at scientific meetings. If this is foreseen, 
the investigator agrees to submit all manuscripts or abstracts to the Sponsor before submission. 
This allows the Sponsor to protect proprietary information and to provide comments. 
The Sponsor will comply with the requirements for publication of study results. In accordance 
with standard editorial and ethical practice, the Sponsor will generally support publication of 
multicenter studies only in their entirety and not as individual study site data. In this case, a 
coordinating investigator will be designated by mutual agreement. 
Authorship will be determined by mutual agreement and in line with International Committee of 
Medical Journal Editors authorship requirements. 
The clinical study plan and the results of the study will be published on www.ClinicalTrials.gov 
in accordance with 21 CFR 50.25(c). The results and data from this study belong to the Sponsor.

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10.2.18 Body Mass Index Charts for Boys and Girls 
For boys from birth to 5 years: 
 

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For boys aged 5 through 19 years: 
 

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For girls from birth to 5 years: 
 

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For girls aged 5 through 19 years: 

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For boys from 6 months to 2 years: 
 

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For girls from 6 months to 2 years 
 
 
 

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10.3 APPENDIX 3: Contraceptive Guidance 
Woman of Childbearing Potential (WOCBP) 
Females of childbearing potential are those who are considered fertile following menarche and 
unless permanently sterile (see below). If fertility is unclear (eg, amenorrhea in adolescents or 
athletes) and a menstrual cycle cannot be confirmed before first dose of IP, additional evaluation 
should be considered. 
Women in the following categories are not considered WOCBP: 
1. Premenarchal 
2. Surgically sterile female with one of the following: 
a. Documented complete hysterectomy 
b. Documented surgical sterilization 
For individuals with permanent infertility due to an alternate medical cause other than the 
above (eg, Mullerian agenesis, androgen insensitivity), investigator discretion should be 
applied in determining study entry. 
Note: Documentation can come from the study site personnel’s review of the 
participant’s medical records, medical examination, or medical history interview. 
Contraception Guidance: 
Adequate female contraception is defined as consistent and correct use of an FDA-approved 
contraceptive method in accordance with the product label, for example: 
Barrier method (such as condoms, diaphragm, or cervical cap) used in conjunction with 
spermicide 
Intrauterine device 
Prescription hormonal contraceptive taken or administered via the oral (pill), transdermal 
(patch), subdermal, or IM route 
Note: While complete abstinence is accepted as adequate female contraception in this age 
group, periodic abstinence (eg, calendar, ovulation, symptothermal, postovulation methods) and 
withdrawal are not acceptable methods of contraception.

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10.4 APPENDIX 4: Adverse Event of Special Interest Terms 
Investigators should report all events which fall into the following categories as an AESI per the 
reporting processes specified in Section 7.4.5. The following AESIs are medical concepts that 
may be related to COVID-19 or are of interest in COVID-19 vaccine safety surveillance. Even if 
the events below occur in the setting of a COVID infection, the event should still be reported as 
an AESI if it is one of the medical concepts below. 
Please note: COVID-19 itself is not an AESI. 
Medical Concept 
Additional Notes 
Anosmia, Ageusia 
 
• 
New onset of anosmia or ageusia associated with COVID-19 
or idiopathic etiology 
• 
DOES NOT INCLUDE anosmia or ageusia associated with 
sinus/nasal congestion, congenital, or traumatic etiologies 
Subacute thyroiditis 
 
• 
Acute inflammatory disease of the thyroid (immune-
mediated or idiopathic) 
• 
DOES NOT INCLUDE new onset of chronic thyroiditis 
Acute pancreatitis 
 
• 
New onset of pancreatitis in the absence of a clear, alternate 
etiology, such as alcohol, gallstones, trauma, recent invasive 
procedure, etc. 
Appendicitis  
• 
Any event of appendicitis  
Rhabdomyolysis 
 
• 
New onset of rhabdomyolysis in the absence of a clear, 
alternate etiology, such as drug/alcohol abuse, excessive 
exercise, trauma, etc. 
Acute respiratory distress 
syndrome (ARDS) 
• 
New onset of ARDS/respiratory failure due to acute 
inflammatory lung injury 
• 
DOES NOT INCLUDE non-specific symptoms of shortness 
of breath or dyspnea, nor events with underlying etiologies 
of heart failure or fluid overload 
Coagulation disorders 
• 
New onset of thrombosis, thromboembolic event, or non-
traumatic hemorrhage/bleeding disorder (ex. stroke, DVT, 
pulmonary embolism, disseminated intravascular coagulation 
(DIC), etc.) 
Acute cardiovascular injury 
• 
New onset of clinically confirmed, acute cardiovascular 
injury, such as myocarditis, pericarditis, arrhythmia 
confirmed by ECG (ex. atrial fibrillation, atrial flutter, 
supraventricular tachycardia), stress cardiomyopathy, heart 
failure, acute coronary syndrome, myocardial infarction, etc. 
• 
DOES NOT INCLUDE transient sinus 
tachycardia/bradycardia, non-specific symptoms such as 
palpitations, racing heart, heart fluttering or pounding, 
irregular heartbeats, shortness of breath, chest 
pain/discomfort, etc. 

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Medical Concept 
Additional Notes 
Acute kidney injury 
• 
New onset of acute kidney injury or acute renal failure in the 
absence of a clear, alternate etiology, such as urinary tract 
infection/urosepsis, trauma, tumor, nephrotoxic 
medications/substances, etc; 
• 
Increase in serum creatinine by ≥ 0.3 mg/dl (or 
≥26.5 µmol/L) within 48 hours; OR 
• 
Increase in serum creatinine to ≥ 1.5 times baseline, known 
or presumed to have occurred within prior 7 days 
Acute liver injury 
• 
New onset in the absence of a clear, alternate etiology, such 
as trauma, tumor, hepatotoxic medications/substances, etc.: 
• 
>3-fold elevation above the upper normal limit for ALT or 
AST; OR 
• 
>2-fold elevation above the upper normal limit for total 
serum bilirubin or GGT or ALP 
Dermatologic findings  
• 
Chilblain-like lesions 
• 
Single organ cutaneous vasculitis 
• 
Erythema multiforme 
• 
Bullous rashes 
• 
Severe cutaneous adverse reactions, such as Stevens-Johnson 
Syndrome, Toxic Epidermal Necrolysis, Drug Reaction with 
Eosinophilia and Systemic Symptoms (DRESS), fixed drug 
eruptions, and necrotic or exfoliative reactions 
Multisystem inflammatory 
disorders  
• 
Multisystem inflammatory syndrome in adults (MIS-A) or 
children (MIS-C) 
• 
Kawasaki’s disease 
• 
Hemophagocytic lymphohistiocytosis (HLH) 
Thrombocytopenia 
• 
Platelet count < 150 × 109/L (thrombocytopenia) 
• 
New clinical diagnosis, or worsening, of thrombocytopenic 
condition, such as immune thrombocytopenia, 
thrombocytopenic purpura, or HELLP syndrome 
Acute aseptic arthritis 
 
• 
Clinical syndrome characterized by acute onset of signs and 
symptoms of joint inflammation without recent trauma for a 
period of no longer than 6 weeks, synovial increased 
leukocyte count and the absence of microorganisms on Gram 
stain, routine culture and/or PCR. 
• 
DOES NOT INCLUDE new onset of chronic arthritic 
conditions 
New onset of or worsening of 
neurologic disease 
• 
Immune-mediated neurological disorders 
• 
Guillain-Barre Syndrome 
• 
Acute disseminated encephalomyelitis (ADEM) 
• 
Peripheral facial nerve palsy (Bell’s palsy) 
• 
Transverse myelitis 
• 
Encephalitis/Encephalomyelitis 

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Additional Notes 
• 
Aseptic meningitis 
• 
Seizures/convulsions/epilepsy 
• 
Narcolepsy/hypersomnia 
Anaphylaxis  
• 
Anaphylaxis associated with study drug administration  
Other syndromes 
 
• 
Fibromyalgia 
• 
Postural Orthostatic Tachycardia Syndrome 
• 
Chronic Fatigue Syndrome 
• 
Myalgic encephalomyelitis 
• 
Post viral fatigue syndrome 
• 
Myasthenia gravis 
 
 

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10.5 APPENDIX 5: Protocol Amendment History 
10.5.1 Amendment 8, 23 May 2022 
Main Rationale for the Amendment: 
The main purpose of this amendment is to unblind recipients receiving placebo who are under 
6 years of age 6 months following their second vaccine dose so that they could be provided the 
option of receiving the crossover vaccine. Given the positive interim analysis data for this age 
group, and the pending regulatory review, at least 6 months of blinded follow up is deemed 
appropriate, and milestone unblinding will be implemented at this point. 
The summary of changes table provided below describes the major changes made to Amendment 
8 relative to Amendment 7, including the sections modified and their corresponding rationales. 
The synopsis of Amendment 8 has been modified to correspond to changes in the body of the 
protocol. Minor copy edits and administrative updates were made throughout the protocol to 
align with new content as well as for clarity and/or accuracy. 
Summary of Major Changes in Protocol Amendment 8: 
Section # and Name 
Description of Change 
Brief Rationale 
1.2.3 (Overall Benefit/Risk 
Conclusion [Table 1]) 
Added “Primary Series” to the 
title 
To differentiate between the 
primary vaccine series and the 
boosters. 
3.1 (General Design) 
Specified that a third dose or a 
booster dose (BD) will be 
assessed. 
To clarify that both the BD and 
third doses will be assessed. 
3.1 (General Design [Table 3]) 
Specified the upper time limit on 
when the third dose will be 
administered in Part 3. 
To clarify that third doses will be 
administered at least 3 months 
and up to 5 months after Dose 2. 
3.1.1 (Study Periods) 
Specified that the duration of the 
study will be up to 24 months 
from enrollment.  
To correct an administrative 
omission. 
3.1.1.2 (Treatment and Follow-
up Period) 
Adapted the language around the 
timepoints of the nasal swabs for 
coronavirus disease (COVID)-19 
testing. 
To clarify the verbiage. 
3.3 (Justification for Dose, 
Control Product, and Choice of 
Study Population) and 8.1.1 
(Breaking the Blind) 
Added that participants under 
6 years of age in Part 2 who have 
reached at least 6 months follow 
up after Dose 2 will be eligible 
for unblinding. 
To allow participants who 
received placebo in the primary 
series to receive mRNA-1273. 

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Section # and Name 
Description of Change 
Brief Rationale 
5.3.1 (Preparation of Study 
Vaccine for Injection) 
Changed the volume of the 
booster for participants under 
6 years from 0.2 to 0.5 mL. 
To correct an administrative 
error (incorporates memo #17, 
from 01 Apr 2022). 
6.3 (Participant 
Discontinuation/Withdrawal 
From the Study) 
Specified that unblinding for 
reasons other than safety or 
health concerns after 6 months 
after Dose 2 will be allowed. 
To allow participants who 
received placebo in the primary 
series to receive mRNA-1273. 
6.4 (Study Pause Rules [Table 
5]) 
Added a footnote to specify that 
the events in participants 
receiving boosters will be 
considered separately from the 
events during the primary 
vaccination series. 
To clarify how pause rule events 
will be analyzed. 
7.1.1 (Use of Electronic Diaries) 
Added that symptom-directed 
physical examination will be 
performed on BD-Day 1 for 
participants who receive 
boosters. 
To clarify when participants 
receiving boosters will have 
physical examination.  
7.1.4 (Physical Examinations) 
Added that eDiaries will be used 
for from BD-Day 43 through 
BD-Day 155 for participants 
who receive boosters. 
To clarify how participants 
receiving boosters will have 
eDiary safety telephone call 
triggered. 
8.1 (Blinding and Responsibility 
for Analyses) 
Clarified procedures for sites 
that have blinded and unblinded 
participants. 
To clarify when the blind should 
be maintained. 
8.1.1 (Breaking the Blind) 
Clarified that participants who 
turn 5 years old during the study 
will be eligible for unblinding. 
Because of the availability of an 
authorized COVID-19 vaccine 
for 5-year-old children. 
8.2 (Statistical Hypothesis) 
Added the description of 
hypothesis testing for BD for the 
participants in Part 1. 
To specify that participants in 
Part 1 who receive a booster will 
be analyzed the same way as 
participants in Part 2 participants 
who receive a booster. 
8.5.3 (Immunogenicity 
Analyses) 
Adapted the description of the 
statistical methods for 
participants in Part 1 and Part 2 
receiving the booster and 
participants in Part 3 receiving 
the third dose. 
To provide more information on 
the statistical methods. 
10.1 (APPENDIX 1: Schedule 
of Assessments, Table 15 and 
footnote) 
• 
Specified that the blood 
draw on Day 209/Day 394 
may be used as the BD-Day 
• 
To minimize the number of 
blood draws. 
 

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Section # and Name 
Description of Change 
Brief Rationale 
1 blood draw if the 2 are 
within 30 days of each 
other. 
 
• 
Added a visit and an 
optional blood draft on BD-
Day 15 for Sub-Cohort E. 
 
 
• 
Changed allowed time 
window for Day 209 and 
Day 394 blood draws from 
±30 days to +30 days. 
 
• 
Added that pre and 
postbooster blood samples 
may be used for analyses of 
cell-mediated immunity 
with exploratory serology. 
• 
To specify that if there are 
no concerning symptoms 
after vaccination, no routine 
vital sign examination is 
needed, except temperature 
at 30 min.  
 
 
 
• 
To allow for an optional 
blood draw for Sub-Cohort 
E on BD-Day 15 
(incorporates memo #17, 
from 01 Apr 2022). 
• 
To correct an 
administrative error 
(incorporates memo #17, 
from 01 Apr 2022). 
 
• 
To specify the purpose of 
the blood sample draws. 
 
 
 
 
• 
To align with the eDiary. 
10.1 (APPENDIX 1: Schedule 
of Assessments, Table 16 and 
footnote) 
• 
Specified that blood draw at 
BD-Day 15 is optional and 
removed the blood draw at 
BD-Day 366 for Sub-
Cohort E. 
• 
Clarified how blood draws 
in participants who were 5 
years old at enrollment but 
turn 6 years old prior to BD 
will be scheduled. 
• 
To minimize the number of 
blood draws in young 
participants. 
 
 
 
• 
To clarify how blood draws 
in participants who were 5 
years old at enrollment but 
turn 6 years old prior to the 
BD will be scheduled. 
10.4 (APPENDIX 4: Adverse 
Event of Special Interest Terms) 
• 
Updated the definitions of 
adverse events of special 
interest. 
• 
To align with updated 
guidance. 
10.5.2 Amendment 7, 18 Feb 2022 
Main Rationale for the Amendment: 

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The main purpose of this amendment is to introduce an optional booster dose for all participants 
in Part 1 (all age groups) and for 6 to < 12 year old participants in Part 2 of the study. While this 
study is primarily designed to assess a 2-dose primary series of mRNA-1273 in children 6 
months to < 12 years, the emergence of the recent SARS-CoV-2 variant of concern ‘Omicron’ 
has shown in adults that protection from infection after 2 doses is less than after booster doses, 
although 2 doses still protect well against severe disease, hospitalization, and death. The optimal 
time after Dose 2 for a booster dose is not known, and recommendations currently range between 
3 to 6 months post Dose 2 around the world for adults who have received the mRNA-1273 
primary series. This amendment will allow participants (Part 1 [all age groups] and for 6 
to < 12 year old participants in Part 2 of the study) to be offered a booster dose 6 months after 
Dose 2 or cross-over Dose 2, depending on whether they received mRNA-1273 at the time of 
enrollment or whether they received placebo followed by cross over vaccination with 
mRNA-1273. Given the staggered enrollment in Part 1 and Part 2, as well as timing of cross-
over, this will allow for the collection of data across a range of boost intervals. 
The dosage level of the booster dose will be based on age at time of booster and will be a lower 
dose than the primary series. Per the experience in adults (for whom the booster dosage level is 
currently half of the primary series), giving a lower booster dose allows for a robust response in 
neutralizing antibodies while reducing reactogenicity and allows for dose sparing, without 
compromising efficacy. 
Summary of Major Changes in Protocol Amendment 7: 
Section # and Name 
Description of Change 
Brief Rationale 
Protocol Synopsis 
Protocol synopsis updated for 
subsequent changes to the body of 
the protocol. 
This was done to reflect all 
changes made during Amendment 
7 and prior. 
Section 1.1 (Study 
Rationale), Section 1.3.3 
(Overall Benefit/Risk 
Conclusions), Section 3.1 
(Study Design), Section 
3.1.1 (Study Periods), 
3.1.1.2 (Treatment and 
Follow-up Period), Section 
3.2 (Scientific Rationale for 
Study Design), Section 3.3 
(Justification for Dose, 
Control Product, and Choice 
of Study Population), 
Section 5.3.1 (Preparation of 
Study Vaccine for Injection), 
Section 5.3.2 
An optional booster dose for all 
participants in Part 1(all age 
groups) and 6 to < 12 year olds in 
Part 2 of the study (10 or 25 µg, 
depending on age at time of 
booster) was added. 
The emergence of the recent 
SARS-CoV-2 variant of concern 
‘Omicron’ has shown in adults 
that protection from infection after 
2 doses is less than after booster 
doses, although 2 doses still 
protect well against severe 
disease, hospitalization, and death. 

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Section # and Name 
Description of Change 
Brief Rationale 
(Administration of Study 
Vaccine), Section 7.2 (Blood 
Collections for 
Immunogenicity 
Assessments and Biomarker 
Samples), Section 7.3.2 
(Surveillance for COVID-19 
Symptoms), Section 8.2 
(Statistical Hypothesis), 
Section 8.3 (Power and 
Sample Size), Section 8.4 
(Analysis Sets), Section 
8.5.3 (Immunogenicity 
Analyses), Section 8.6.1 
(Interim Analyses), Section 
10.1 (Schedule of 
Assessments) 
Section 1.2.2 (Clinical 
Studies), Section 3.1 
(General Design), Section 
3.1.1.2 (Treatment and 
Follow-up Period) 
Added that participants opting to 
receive a booster dose in Parts 1 
and 2 will be followed for 12 
months after last dose. 
This clarifies that if a participant 
receives a booster, they will be 
followed for 12 months after the 
booster and not Dose 2 (ie, the last 
dose). 
Section 2 (Objectives and 
Endpoints), Section 8.2 
(Statistical Hypothesis), 
Section 8.3 (Power and 
Sample Size), Section 8.5.3 
(Immunogenicity Analyses) 
To infer effectiveness of the 
mRNA-1273 booster by 
establishing noninferiority of Ab 
response after the booster dose 
compared with primary series from 
adults 18 to 25 years of age in Part 
2.  
Provided the statistical hypothesis, 
power and sample size, and 
analysis methods for the booster 
dose phase analyses in Part 2.  
Section 3.1.1 (Study 
Periods) 
Study period updated to include an 
approximate duration of 24 months 
if a participant decides to receive a 
booster dose. 
Study duration was updated given 
changes to study design. 
Section 3.1.1.2 (Treatment 
and Follow-up Period), 
Section 7.1.5 (Assessment 
for SARS-CoV-2 Infection), 
Section 7.3.2 (Surveillance 
for COVID-19 Symptoms), 
Section 7.3.3 
(Follow-up/Convalescent 
Period After Diagnosis with 
COVID-19), Section 10.1 
(Schedule of Assessments) 
Convalescent visits are not 
required, and may be scheduled at 
the discretion of the investigator. 
These visits, originally described 
to be scheduled approximately 28 
days after diagnosis of COVID-
19, were determined not to be 
required any more, but may be 
scheduled at the discretion of the 
investigator. 

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Section # and Name 
Description of Change 
Brief Rationale 
Section 7.1.5 (Assessment 
for SARS-CoV-2 Infection) 
SARS-Cov-2 assessment updated. 
This section was updated to 
clarify the follow-up actions 
needed for asymptomatic children 
and allow for local diagnostic 
screenings in lieu of a study visit, 
as applicable. 
Section 7.4.4 (Medically 
Attended Adverse Events) 
Only severe COVID-19 cases will 
need to be reported to the Sponsor 
or designee immediately and in all 
circumstances within 24 hours, 
using the SAE reporting structure.  
The original wording was an error 
and this edit was made to clarify 
that only severe COVID-19 cases 
need to be reported as indicated.  
Global 
Terminology change: The “booster 
dose” for Part 3 was changed to 
“third dose.” 
This was done to differentiate 
between the third dose design in 
Part 3 versus the booster dose 
being offered to select participants 
in Parts 1 and 2. 
Global 
Editorial changes were made 
throughout for Amendment 7. 
Editorial changes were made to 
update and harmonize 
Amendment 7 changes throughout 
the protocol and align with other 
Sponsor studies, as needed. 
 
10.5.3 Amendment 6, 07 Jan 2022 
Main Rationale for the Amendment: 
The main purpose of this Amendment is to add an additional part to the study (Part 3) aimed at 
studying the safety, tolerability, reactogenicity, and immunogenicity of a lower dose level and 
regimen for 6 years to < 12 year old children that could be implemented. The addition of an 
Open-Label Study Arm 14 for this age group with a sample size of approximately 
300 participants who will receive two doses of 25 µg one month apart followed by a booster at 
least 3 months after the second dose will allow for assessment of reactogenicity and 
immunogenicity of this lower dose in 6 years to < 12 years old. 
The summary of changes table provided below describes the major changes made to Amendment 
6 relative to Amendment 5, including the sections modified and corresponding rationales. The 
synopsis of Amendment 6 has been modified to correspond to changes in the body of the 
protocol. Minor copy edits and administrative updates were made throughout the protocol to 
align with new content as well as for clarity, readability, and/or accuracy. 

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Summary of Major Changes in Protocol Amendment 6: 
Section # and Name 
Description of Change 
Brief Rationale 
Section 1.1. (Study 
Rationale)  
Made updates to add that an 
mRNA-based vaccine has been 
granted Emergency Use 
Authorization for children aged 5 
to 11 years old  
Updated to reflect the current 
regulatory landscape of 
coronavirus disease 2019 
(COVID-19) vaccines 
Section 1.3.3. (Overall 
Benefit/Risk Conclusion), 
Section 3.1. (General 
Design), Section 3.2. 
(Scientific Rationale for 
Study Design), Section 
5.3.2. (Administration of 
Study Vaccine), Section 
7.1.4. (Physical 
Examinations), Section 7.2. 
(Blood Collections for 
Immunogenicity 
Assessments and Biomarker 
Samples), Section 10.1 
(APPENDIX 1: Schedule of 
Assessments; Tables 13 and 
14) 
Added Part 3 (Study Arm 14) 
which is the 25-µg dose to be 
evaluated as an alternative (lower 
dosing) dosing regimen with a 
primary series (2 doses) followed 
by a booster dose (1 dose) 
 
Changes made to test an 
alternative (lower dosing) dosing 
regimen to test safety and efficacy 
in a lower dose 
Section 2. (Objectives and 
Endpoints) 
Added endpoints for the added 
booster dose in Part 3 
Added to account for the addition 
of the booster dose in Part 3  
Section 4.1. (Inclusion 
Criteria) 
Added language to inclusion 
criterion #6 about contraceptive 
use with the booster dose 
Added to account for the addition 
of the booster dose in Part 3 
Section 6.3.1. (End-of-Study 
Visit [Prior to Day 394 or 
Day 514/BD-Day 366])  
Added this section  
Added to incorporate Protocol 
Clarification Memo #9 
Section 7.1.5. (Assessment 
for SARS-CoV-2 Infection) 
Added information about the use of 
home tests during a surge in 
SARS-CoV-2 cases 
Added to incorporate Clarification 
Memo #11 
Section 7.1.5. (Assessment 
for SARS-CoV-2 Infection) 
Added information about visits 
within 90 days of a positive 
COVID-19 test 
Added to align with US Centers 
for Disease Control and 
Prevention guidance  
Section 8.2. (Statistical 
Hypothesis), Section 8.3. 
(Power and Sample Size), 
Section 8.4. (Analysis Sets), 
Section 8.5.3. 
Added statistical methods for Part 
3 (Study Arm 14) 
Added to account for the addition 
of the booster dose in Part 3  

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Section # and Name 
Description of Change 
Brief Rationale 
(Immunogenicity Analyses), 
Section 8.6.1 (Interim 
Analyses) 
Section 10.1. (APPENDIX 
1: Schedule of Assessments; 
Table 11) 
Added 2 rows in Table 11 for the 
days since most recent injection 
and pregnancy test 
 
Added information about when a 
COVID-19 vaccine becomes 
available and a participant requests 
to unblind 
Added to incorporate Protocol 
Clarification Memo #9 and 10 
10.5.4 Amendment 5, 29 Sep 221 
Main Rationale for the Amendment: 
This amendment is considered to be non-substantial based on the criteria set forth in Article 
10(a) of Directive 2001/20/European Commission (EC) of the European Parliament and the 
Council of the European Union. 
The main rationale for this amendment is to simplify the process for potential cross-over 
vaccination given the increased sample size of the study and to ensure retention in the study for 
safety follow-up, incorporate Clarification Memo #8, align with the Cardiac Event Adjudication 
Committee (CEAC) charter, and clarify the Data Safety Monitoring Board (DSMB) safety data 
review process for the younger age groups (2 to < 6 years; 6 months to < 2 years) to match the 
process in the older age group (6 to < 12 years) and allow DSMB review of Part 1 (open-label 
phase) data before start of Part 2 (blinded phase) for the younger age groups. Additional updates 
were made to clarify the statistical analysis plan, including the inferred efficacy analysis and 
interim analyses. 
The summary of changes table provided below describes the major changes made to Amendment 
5 relative to Amendment 4, including the sections modified and corresponding rationales. The 
synopsis of Amendment 5 has been modified to correspond to changes in the body of the 
protocol. Minor copy edits and administrative updates were made throughout the protocol to 
align with new content as well as for clarity, readability, and/or accuracy. 
Section # and Name 
Description of Change 
Brief Rationale 
Section 3.1 (General Design; 
Figure 1), Section 3.1.1.2 
(Treatment and Follow-up 
Period), Section 7.2 (Blood 
Collections for 
Immunogenicity 
Made updates to explain that blood 
sample collection for participants 
in Cohort D will be prior to 
randomization and the first dose at 
Day 1 and within 4 days of 
For clarification. 

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Section # and Name 
Description of Change 
Brief Rationale 
Assessments and Biomarker 
Samples), Appendix 1 
(Schedule of Assessments; 
Table 10) 
receiving Dose 2 at Day 30 (+ 3 
days). 
Section 3.3 (Justification for 
Dose, Control Product, and 
Choice of Study Population), 
Appendix 1 (Schedule of 
Assessments) 
Made updates to Section 3.3 to 
clarify the justification for the 
choice of study population, 
including unblinding of eligible 
study participants, placebo 
recipient cross-over vaccination, 
booster dose eligibility for 
participants who received a lower 
dose in Part 1 than was ultimately 
approved for their respective age 
group in Part 2, and study 
discontinuation for participants 
receiving an EUA vaccine outside 
the protocol. 
 
In accordance with changes made 
to Section 3.3, updated text and 
Table 11 in Appendix 1 to clarify 
placebo recipient cross-over 
vaccination. 
Given the increase in sample size, 
unblinding via clinic visit is no 
longer feasible and will instead be 
performed over the phone, if 
desired by the family. To ensure 
retention in the study for safety 
follow-up, cross-over vaccination 
will be offered to all placebo 
recipients per their request if any 
COVID-19 vaccine (mRNA-1273 
or other) becomes authorized or 
licensed for their age group. 
Section 4.2 (Exclusion 
Criteria) 
Added text to exclusion criteria #8 
to provide context related to the 
influenza vaccine. 
For incorporation of Clarification 
Memo #8. 
Section 6.1.1 (Individual 
Participant Criteria for Delay 
of Study Vaccination) 
Provided text in Section 6.1.1 to 
describe additional reasons to delay 
study vaccination for participants. 
For incorporation of Clarification 
Memo #8. 
Section 7.3.3 
(Follow-up/Convalescent 
Period After Diagnosis with 
COVID-19) 
Deleted text, “Study participants 
will be monitored by trained study 
site personnel for a 28 day period 
after diagnosis.” 
For accuracy. 
 
Section 7.4.5 (Adverse 
Events of Special Interest), 
Section 7.5.2 (Data Safety 
Monitoring Board) 
Clarified that the CEAC will 
review suspected cases of 
myocarditis/pericarditis to 
determine if they meet CDC 
criteria of “probable” or 
“confirmed” event and to assess 
severity, but recommendations to 
the Sponsor to continue vaccine 
dosing will be made by DSMB. 
To align with CEAC charter. 

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Section # and Name 
Description of Change 
Brief Rationale 
Section 7.5.2 (Data Safety 
Monitoring Board) 
Changed description of timing of 
DSMB review and scope for 
younger age groups (2 to < 6 years; 
6 months to < 2 years) from 
separate reviews in each age group 
with data from Part 1 and Part 2 
during the conduct of Part 2 to one 
review of all available Part 1 safety 
data for all doses used in < 6 years 
before start of Part 2 for each age 
group. 
To allow the DSMB to review 
data from Part 1 (open-label 
phase) for all doses used in < 6 
year old participants before 
starting Part 2 for 2 to < 6 years 
and 6 months to < 2 years age 
groups. 
Section 8.5.4 (Inferred 
Efficacy Analysis) 
Added text to explain the 
following: 1) analyses of efficacy 
endpoints in Part 2 will be 
performed for the randomized 
blinded phase, and 2) additional 
exploratory analyses will be 
conducted in the blinded and 
unblinded phases for participants 
randomized to mRNA-1273 in Part 
2, and in the unblinded phase for 
participants who are originally 
randomized to the placebo arm and 
cross-over to mRNA-1273 after 
use of any COVID-19 vaccine is 
authorized or licensed for the 
participant’s age group.  
For clarification. 
Section 8.6.1 (Interim 
Analyses) 
Updated description of Part 2 to 
indicate that an interim analysis of 
immunogenicity and safety will be 
performed after all or a subset of 
participants have completed Day 
57 (1 month after the second dose) 
in Part 1 or Part 2 within an age 
group. 
For clarification. 
Appendix 1 (Schedule of 
Assessments; Table 10 and 
Table 11) 
Updated footnote #2 in Table 10 
and added footnote #2 to Table 11 
to include cross-references for 
Section 6.1.1. 
For alignment. 
Abbreviations: CDC = Centers for Disease Control and Prevention; CEAC = Cardiac Event Adjudication 
Committee; COVID-19 = coronavirus disease 2019; DSMB = Data Safety Monitoring Board; EUA = Emergency 
Use Authorization; mRNA = messenger RNA; SoA = Schedule of Assessments. 
 
 

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10.5.5 Amendment 4, 25 Aug 2021 
Main Rationale for the Amendment: 
The main rationale for this amendment is to introduce an additional blood draw within 4 days 
after the second dose for participants in Cohort D in Part 2 in each age group. The samples will 
be stored for potential future analysis per a request from the FDA. For participants already 
enrolled in Cohort D prior to protocol amendment 4 implementation at the site, this blood draw 
will be optional and confirmed at time of re-consenting; for all participants newly enrolled into 
Cohort D under amendment 4, it will be mandatory. 
Summary of Major Changes in Protocol Amendment 4: 
Section # and Name 
Description of Change 
Brief Rationale 
Title Page, Signature 
page, Synopsis, and 
Header 
Updated the protocol version and 
date. 
Updated to reflect the new version and 
date.  
Global 
Minor grammar and formatting 
corrections were made throughout 
the document. 
Updates were made for clarity and 
readability.  
Synopsis, 
Section 3.1.1.2 
(Treatment and 
Follow-up period), and 
Section 10.1 (Appendix 
1 Schedule of 
Assessments - 
Table 10)  
Language was added to clarify that 
the 300 participants in the Arm 1 
and 2 expansions will have a 
scheduled Day 1 blood draw and a 
voluntary blood draw on Day 57. 
To clarify that only expansion portion 
of Arms 1 and 2 have a voluntary Day 
57 blood draw, but that blood draws are 
mandatory for all other Arms in part 1 
(as per Clarification Memo # 7). 
Synopsis, Section 3.1 
(General Design - 
Figure 1b), 
Section 3.1.1.2 
(Treatment and 
Follow-up period), 
Section 7.2 (Blood 
Collections for 
Immunogenicity 
Assessments and 
Biomarker Samples), 
and Section 10.1 
(Appendix 1 Schedule 
of Assessments - 
Table 10) 
Day 30 (+3 days) blood draw was 
added to indicate that participants 
in Cohort D (remainder of the age 
group) will provide a blood sample 
at Day 1 and at Day 30 (+3 days) 
for storage and potential future 
biomarker testing. 
Day 30 (+3 days) blood draw was 
added per the request from the FDA.  
Synopsis, Section 7.2 
(Blood Collections for 
Immunogenicity 
Assessments and 
Header in Section 7.2 was updated 
from “Immunogenicity 
Assessments” to “Blood 
Collections for Immunogenicity 
Headings and titles were updated for 
clarity and consistency with content 
under heading. 

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Section # and Name 
Description of Change 
Brief Rationale 
Biomarker Samples), 
Section 10.1 (Appendix 
1 Schedule of 
Assessments) - Table 
10 (Schedule of 
Assessments), and 
Table 12 (Phlebotomy 
Schedule for Serology, 
Biomarker Samples, 
and Cell-Mediated 
Immunity for Part 2 
[Expansion] of the 
Study) 
Assessments and Biomarker 
Samples” 
 
A note was added to Section 7.2 
indicating that if less than 8 mL of 
blood is drawn at baseline then the 
child cannot be enrolled. 
 
Table 12 title in Section 10.1 was 
updated to include “Biomarker 
Sample.” 
 
Language and/or column was 
added to each section to indicate 
that there will be a Day 30 (+3 
days) blood draw for storage and 
potential future biomarker testing 
for Cohort D in Part 2, and that the 
volume will be ~4 mL for all age 
groups. 
 
 
Blood volume was indicated as this is a 
pediatric study. 
 
Note language was added for clarity on 
enrollment procedure. 
Synopsis and Section 
7.4.5 (Adverse Events 
of Special interest) 
The Cardiac Endpoint 
Adjudication Committee’s name 
was updated to the officially 
recognized name as the “Cardiac 
Event Adjudication Committee”. 
This change was to align the committee 
language across all relevant Moderna 
studies.  
Section 7.1.5 
(Assessment for SARS-
CoV-2 Infection) 
Language was added to specify 
that exposure to an individual in 
the household confirmed to be 
infected with SARS-CoV-2 will 
require a study illness visit.  
This clarification was made to capture 
highest risk exposure only. 
Section 7.3.2 
(Surveillance for 
COVID-19 Symptoms) 
Language was added to specify 
when an illness visit would be 
required.  
Clarification of circumstances that 
require an illness visit. 
 
Section 10.2.10 
(Sample Retention and 
Future Biomedical 
Research) 
Language was added to indicate 
that the samples collected and 
stored from Cohort D in Part 2 may 
undergo additional exploratory 
analysis using Ab-based 
methodologies. 
To reflect the addition of a Day 30 
blood sample that will be stored but 
only analyzed if an appropriate 
biomarker is identified. 
 
 

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10.5.6 Amendment 3, 23 Jul 2021 
Main Rationale for the Amendment: 
The main rationale for this amendment is to add a case definition for myocarditis and pericarditis 
as well as guidance for reporting and assessing suspected cases for this study, given the recent 
emergence of a temporal association between mRNA vaccine administration and signs and 
symptoms of myocarditis/pericarditis. 
In addition, the sample size for each age group in Part 2 (blinded part) is increased to allow for a 
95% probability to detect a rare adverse event occurring at a rate of 1 in 1,000. 
Summary of Major Changes in Protocol Amendment 3: 
Section # and Name 
Description of Change 
Brief Rationale 
Title Page, Signature 
page, Synopsis, and 
Header 
Updated the protocol version and 
date. 
Updated to reflect the new version and 
date.  
Global 
Minor grammar and formatting 
corrections were made throughout 
the document. 
Updates were made for clarity and 
readability.  
Synopsis, Section 3.1 
(General Design), 
Section 5.2 
(Randomization), and 
Section 8.3 (Power and 
Sample Size) 
The overall sample size for Part 2 
was updated to approximately 
12,000 participants. 
 
The overall sample size for each 
age group was updated to up to 
4,000 participants. 
 
The sample size for Study Arms 8, 
10, and 12 were each updated to up 
to 3,000 participants. 
 
The sample size for Study Arms 9, 
11, and 13 were each updated to up 
to 1,000 participants.  
Samples sizes were increased to allow 
for a 95% probability to detect a rare 
adverse event occurring at a rate of 1 in 
1,000. 
Synopsis, Section 2 
(Objectives and 
Endpoints), Section 3.1 
(General Design) - 
Study Progression, 
Section 6.2 
(Discontinuing Study 
Vaccination), 
Section 7.1 (Safety 
Assessments and 
AESIs of Myocarditis and/or 
pericarditis were added (in addition 
to MIS-C). 
To reflect addition of case definition for 
myocarditis and pericarditis in AESI 
section. 

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Section # and Name 
Description of Change 
Brief Rationale 
Procedures), and 
Section 10.1 (Appendix 
1: Schedule of 
Assessments - Table 10 
and Table 11) 
Synopsis, Section 7.4.5 
(Adverse Events of 
Special Interest), and 
Section 7.5.2 (Data 
Safety Monitoring 
Board) 
Included language for the addition 
of an external clinical endpoint 
adjudication committee, that will 
adjudicate any suspected cases of 
myocarditis, pericarditis, or 
myopericarditis and make 
recommendations in consultation 
with the DSMB to the Sponsor. 
To reflect the addition of an external 
clinical endpoint adjudication 
committee for cases of 
myocarditis/pericarditis to the safety 
oversight of the study. 
Section 1.3.2 (Risks to 
Study Participation and 
Their Mitigation) 
 
Added paragraph on very rare 
reports of myocarditis and 
pericarditis occurring after 
vaccination with Moderna COVID-
19 Vaccine under Emergency Use 
Authorization in adults aged 18 
years and older. 
To reflect addendum made to 
Investigator’s Brochure. 
Section 7.4.4 
(Medically Attended 
Adverse Events) 
Language was updated to 
Unsolicited AEs will be captured 
on the AE page of the eCRF.  
To reflect the correct method of 
collecting unsolicited AEs.  
Section 7.4.5 (Adverse 
Events of Special 
Interest) 
Added CDC case definitions for 
myocarditis and pericarditis. 
To provide guidance to the 
investigators regarding assessing and 
reporting myocarditis and pericarditis 
for this study population. 
Section 10.4 (Appendix 
4: Adverse Event of 
Special Interest Terms) 
Appendix 4 was added to the 
protocol. 
To include AESI list in the protocol 
instead of a separate document.  
10.5.7 Amendment 2, 17 Jun 2021 
Main Rationale for the Amendment: 
The main rationale for this amendment is to add an optional blood collection on Day 57 for 
participants in the expansion part of Arm 1 and Arm 2 to gather additional data on 
immunogenicity. The handling of potential unblinding requests in Part 2 is further clarified. In 
addition, the decision in Part 1 to not evaluate the 100-µg dose in participants less than 2 years 
old is integrated into this amendment by removing Arm 7 (6 months to < 2 years, 100 µg dose) 
from this age group. The change in dose level is based on moderate, increased reactogenicity 
observed in Arm 2 (6 to < 12 years of age, 100 µg), which led to the decision to not evaluate the 
100-µg dose in the 2 to < 6 years age group. In order to maintain dose-ranging in the 2 to < 6 

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years age group, Arm 7 may instead enroll participants in this age group to evaluate the 25-µg 
dose if the 100-µg dose is eliminated at any point during the dose-escalation process. 
The Summary of Major Changes table describes the major changes made in Amendment 2, 
including the sections modified and the corresponding rationales. The synopsis of Amendment 2 
has been modified to correspond to changes in the body of the protocol. 
Summary of Major Changes in Protocol Amendment 2: 
Section # and 
Name 
Description of Change 
Brief Rationale 
Protocol Synopsis 
and Section 3.1 
General Design 
Clarified that preliminary safety and 
immunogenicity data of Arm 1 (6 to < 
12 years of age, 50 µg) and Arm 2 (6 to 
< 12 years of age, 100 µg), as 
applicable, will aid in the selection of a 
dose level for Part 2. 
Tolerability and safety data will be 
available from both doses (50 and 100 
µg) and will be an essential metric for 
dose selection. Additionally, 
immunogenicity data from the 50-µg 
dose (a dose lower than the 100-µg 
dose assessed in the P301 adult efficacy 
trial) will allow for assessment of the 
likelihood of the 50-µg dose to meet 
noninferiority criteria. These data will 
allow an informed dose selection 
decision for Part 2. 
Protocol Synopsis 
and Section 3.1 
General Design 
Revised the age group and dose level of 
Arm 7 (6 months to < 2 years of age, 
100 µg) to 2 to < 6 years and 25 µg of 
mRNA-1273. Arm 7 was made optional, 
the 25-µg dose will be evaluated if 100-
µg dose is eliminated at any point during 
the dose-escalation process, to maintain 
dose ranging. 
The 100-µg dose was not evaluated in 
participants aged < 2 years based on the 
internal safety team recommendation. 
The dose level and age group of Arm 7 
was revised to maintain dose-ranging in 
the 2 to < 6 years age group by adding a 
lower dose than originally planned 
(25 µg). 

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Section # and 
Name 
Description of Change 
Brief Rationale 
Section 3.3 
Justification for 
Dose, Control 
Product, and 
Choice of Study 
Population 
Clarified that if a COVID-19 vaccine 
(mRNA-1273 or other) is authorized or 
licensed, eligible study participants will 
be offered the opportunity to unblind, 
and a nasal swab and a blood sample 
will be collected. Participants who 
received mRNA-1273 will continue in 
the study. If a participant previously 
received placebo and mRNA-1273 is 
authorized for use in the participant’s 
age group, the participant will be offered 
unblinding followed by a cross-over 
vaccination with mRNA-1273. If 
mRNA-1273 is not yet authorized for 
the relevant age group, but an alternative 
vaccine is authorized, previous placebo 
recipients may seek the alternative 
vaccine and withdraw from study. 
To clarify plans for unblinding 
requests. 
Section 7.4.3 
Solicited Adverse 
Reactions Table 7 
Revised the temperature ranges for fever 
in Table 7: Solicited Adverse Reactions 
and Grades: Age 6 to ≤ 36 Months. 
To correct the temperature cut-offs for 
consistency with internal Moderna 
standard for the 6 to ≤ 36 months age 
group. 
Protocol Synopsis 
and Section 7.5.2 
Data Safety 
Monitoring Board 
Clarified that the DSMB will review 
safety data from a subset of 
approximately 300 participants at the 
selected dose level in the 6 to < 12 years 
age group rather than the full safety set 
for Arm 1 and Arm 2 from Part 1 
(N = 750 participants) before allowing 
the start of enrollment in Part 2. 
Dose selection will be based on safety 
data from approximately 300 
participants. Approximately 300 
participants will have reached Day 43. 
This will expedite expansion of the 
study. The safety review will still allow 
for detection of an AE occurring at a 
rate ~ 1% (N = ~ 375 participants per 
group remains the same). 
Protocol Synopsis 
and Section 7.5.2 
Data Safety 
Monitoring Board 
For both the middle age group (2 to < 6 
years) and the youngest age group (6 
months to < 2 years) the DSMB will 
review cumulative safety data after 
approximately 400 participants have 
been exposed to mRNA-1273 at selected 
dose in each age group, combining 
participants from Part 1 and Part 2, 
before further expansion in each 
respective age group. 
To reflect changes made to dose 
escalation for < 6 year olds in Part 1 
(elimination of 100 µg group), and to 
moderately increase the subset of 
participants exposed at chosen dose 
level before final expansion in Part 2 
(N= ~375 participants per group was 
updated to N= ~400 participants per 
group). 

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Section # and 
Name 
Description of Change 
Brief Rationale 
Protocol Synopsis 
and Section 8.6.1 
Interim Analyses 
Clarified that the interim analyses in 
Part 1 will be optional and will be 
performed after all or a subset of 
participants have completed Day 57. 
Clarified that the interim analysis in Part 
2 will be performed after all or a subset 
of participants have completed Day 57. 
To reflect changes made to dose 
selection plans that will expedite the 
expansion of the study. 
Section 10.1 
Appendix 1: 
Schedule of 
Assessments 
Added an optional blood collection for 
immunogenicity on Day 57 for the 
expansion part of Arm 1 and Arm 2. 
An optional blood collection was added 
for the expansion part of Arm 1 and 
Arm 2 to gather additional 
immunogenicity data in Part 1. 
10.5.8 Amendment 1, 30 Apr 2021 
Main Rationale for the Amendment: 
The main purpose of this amendment is to allow a Data Safety Monitoring Board (DSMB) safety 
review when approximately 375 children have received mRNA-1273 in each age group, before 
expanding enrollment to each full age cohort. This review will allow assessment of less frequent 
adverse events (AEs), occurring at a rate of approximately 1 in 100. Per this amendment, this 
will be achieved in different ways for each of the 3 age groups: 
1. For the 6 to < 12 years of age group: To expedite this formal safety review in school-aged 
children, an additional 300 participants will be enrolled to each dose level in Part 1 (ie, to 
have n = 375 per dose group), and the DSMB will review Day 57 safety data for all 375 
participants in each dose group before advancing this age group to Part 2. 
2. For the 2 to < 6 years and 6 months to < 2 years of age groups: DSMB safety review will 
occur within Part 2, at a time when it is anticipated that a total of approximately 
375 participants (accounting for the 3:1 randomization to vaccine or placebo in the 
blinded Part 2) have been exposed to mRNA-1273 at the dose level selected for Part 2. 
DSMB will occur when Day 57 safety data from this subset is available for review. 
The Summary of Changes table provided here describes the major changes made in 
Amendment 1 relative to the original protocol, including the sections modified and the 
corresponding rationales. The synopsis of Amendment 1 has been modified to correspond to 
changes in the body of the protocol. 
 
 

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Summary of Major Changes in Protocol Amendment 1: 
Section # and Name 
Description of Change 
Brief Rationale 
Title Page, Protocol 
Approval Page, and 
Protocol Amendment 
Summary of Changes 
Updated protocol version and 
date. Added Protocol Amendment 
Summary of Changes. 
 
Medical monitor/sponsor contact 
information was updated. 
Updated to reflect new 
version, date of protocol, and 
new medical monitor/sponsor 
contact. Protocol Summary of 
Changes added to be in line 
with Moderna guidelines.  
Global  
Minor grammar and formatting 
corrections were made throughout 
the document.  
Updates were made for clarity 
and readability.  
Global 
Primary endpoint language was 
updated to use ‘antibody’ rather 
than ‘nAb.’  
To reflect potential use of 
binding antibody at time of 
analysis, if available.  
Protocol Synopsis and 
Section 2 (Objectives and 
Endpoints) 
The Secondary Objective “to 
evaluate the incidence of 
SARS-CoV-2 infection after 
vaccination with mRNA-1273 or 
placebo” Endpoint language was 
updated.  
To maintain consistency 
across all Moderna protocols.  
Protocol Synopsis and 
Section 2 (Objectives and 
Endpoints) 
The secondary objective “To 
evaluate the incidence of 
asymptomatic SARS-CoV-2 
infection after vaccination with 
mRNA-1273 or placebo” Endpoint 
language was updated.  
To maintain consistency with 
other mRNA-1273 related 
protocols. Additionally, this 
language was updated to clarify 
that only participants without 
evidence of prior infection at 
baseline will be included in the 
analysis of the secondary 
objective of asymptomatic 
infection with SARS-CoV-2. 
Protocol Synopsis and 
Section 2 (Objectives and 
Endpoints) 
The following exploratory objective 
was added, “To explore 
asymptomatic SARS-CoV-2 
infection after vaccination with 
mRNA-1273 or placebo in 
participants with serologic evidence 
of infection at baseline.” 
The corresponding exploratory 
endpoint was added, “GM and 
GMFR of bAb levels against SARS-
CoV-2 nucleocapsid protein 
(quantitative IgG)” 
 
To explore serological evidence 
of asymptomatic infections in 
seropositive participants.  

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Section # and Name 
Description of Change 
Brief Rationale 
New abbreviations were added to the 
footnote. 
Synopsis and Section 2 
(Objectives and Endpoints)  
The definition of COVID-19 
infection was updated to match the 
CDC guidelines and the details of 
this guideline was moved to the 
footer.  
To reflect the generally milder 
and more varied presentation of 
SARS-CoV-2 infection in the 
pediatric population, matching 
the secondary case definition in 
adult study (P301/COVE study). 
Section 3.1 (General 
Design) Figure 1 (Study 
Schema)  
Study Schema was updated to correct 
typographical error. 
Figure updated to ensure 
consistency throughout protocol.  
Protocol Synopsis and 
Section 4.1 (Inclusion 
Criteria) 
Language was added to clarify that 
the height and weight of children < 2 
years of age must both meet or 
exceed the 3rd percentile according to 
WHO Child Growth Standard at the 
Screening Visit.  
Height and weight are better 
measures of growth than BMI 
for children < 2 years of age. 
Protocol Synopsis and 
Section 4.1 (Inclusion 
Criteria)  
The heading before criterion 7, 
“Special inclusion criteria for 
children 6 months to < 2 years of 
age” was updated to “Special 
inclusion criteria for children 6 
months to < 12 months of age”.  
Exclusion of prematurity is 
considered relevant only for 
children under 12 months of age 
in the context of mRNA 
vaccines (not live vaccines). 
Protocol Synopsis and 
Section 4.2 (Exclusion 
Criteria)  
A note was added to the exclusion of 
febrile seizures to indicate that a 
history of a simple, single febrile 
seizure is allowed for children 
6 years and older in Part 2 of the 
study.  
The risk of febrile seizures is 
most relevant for children up to 
6 years of age. Once the safety 
data has been reviewed in Part 1, 
children 6 years of age and older 
can be included even with a 
history of a single, simple febrile 
seizures. 
Protocol Synopsis, Section 
3.1 (General Design), 
Section 5.2 
(Randomization), and 
Section 8.3 (Power and 
Sample Size) 
The sample size was increased from 
750 to 1,350 participants in Part 1. 
 
Sample size in Part 2 was adjusted in 
the 6 to < 12 years of age group from 
2,000 to 1,700 (mRNA-1273 arm 
~1,275 participants; placebo arm 
~425 participants).  
To reflect changes per main 
rationale for Amendment. 
 
Protocol Synopsis, Section 
3.1 (General Design), 
Section 8.5.3 
(Immunogenicity Analyses), 
and Section 8.6.1 (Interim 
Analyses) 
Language was updated to reflect 
when the primary immunogenicity 
analysis will be done for Part 2. 
To reflect adjustment in the 
safety oversight plan. 

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Section # and Name 
Description of Change 
Brief Rationale 
Synopsis and Section 7.5.2 
(Data Safety Monitoring 
Board)  
Language was added to update the 
plan for the review process.  
To update and clarify the 
changes made to the process 
based on main reason for 
amendment.  
Protocol Synopsis, Section 
8.2 (Statistical Hypothesis), 
and Section 8.3 (Power and 
Sample Size) 
Coprimary endpoint 1 and 2 language 
updated.  
To reflect updates to the 
statistical plan. 
Protocol Synopsis and 
Section 8.5.3 
(Immunogenicity Analyses) 
Language for multiplicity adjustment 
between age groups was added. 
To reflect updates for the 
statistical plan.  
Section 3.3 (Justification for 
Dose, Control Product, and 
Choice of Study Population) 
Language was updated to indicate 
that if immunogenicity criteria are 
successfully met in P204 age cohorts, 
blinded placebo participants will be 
given the opportunity to receive the 
mRNA-1273 vaccine, and 
participants who received a lower 
dose than the dose receiving 
Emergency Use Authorization will 
be provided a booster with the 
‘optimal dose’ for a given age group. 
To describe the planned 
approach to dosing placebo 
recipients and lower dose 
recipients in case of Emergency 
Use Authorization of 
mRNA-1273 for each age group 
during the conduct of the trial. 
Section 7.1.5 (Assessment 
for SARS-CoV-2 infection) 
Language was updated to include 
further clarification on procedures to 
follow when participant is exposed to 
an individual with confirmed 
SARS-CoV-2 infection. A definition 
of last exposure was also added. 
 
Language was added to clarify that 
an initial assessment will be 
performed at a study illness visit to 
determine general appearance, and to 
provide details as to whom may 
perform the assessment. 
To provide a clear definition of 
last exposure, and the processes 
and timing to follow when a 
participant is exposed to a 
confirmed SARS-CoV-2 
infected person. 
 
Clarification of which providers 
can perform initial assessments 
for illness visits. 
Section 7.3.1 (Vaccine 
Effectiveness Assessments) 
Table 5 (Age-Specific 
Cut-Offs for Vital Signs and 
Laboratory Variables) 
Removed irrelevant ages (rows). 
Systolic Blood pressure parameter 
updated to include hypotension 
parameters for pediatric population. 
To ensure age-appropriate 
information is included in 
definition of Severe COVID-19. 
Synopsis, Section 2 
(Objectives and Endpoints), 
and Section 7.3.1 (Vaccine 
Effectiveness Assessments)  
The definition of a SARS-CoV-2 
infection was updated. 
To reflect pediatric 
manifestations of SARS-CoV-2 
infection and match CDC case 
definition. 

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Section # and Name 
Description of Change 
Brief Rationale 
Section 7.3.1 (Vaccine 
Effectiveness Assessments) 
Table 6 (Definition of renal-
, liver-, and neurological 
dysfunction for Pediatric 
Population (< 12 years of 
age) 
Table 6 was added to define renal, 
liver, and neurological dysfunction 
for this study. 
To define severe COVID-19 
with age-appropriate definitions 
and objective measures. 
Section 7.3.2 (Surveillance 
for COVID-19 Symptoms:) 
Language was added to provide 
guidance for omitting or conducting 
an illness visit for febrile children 
that have an alternative diagnosis 
identified. 
To match the American 
Academy of Pediatrics guidance 
on COVID-19 testing in 
children. 
Section 7.3.3 
(Follow-up/Convalescent 
Period After Diagnosis with 
COVID-19) 
Language was added to provide 
guidance for children hospitalized 
with possible or confirmed MIS-C. 
Clarification of sample 
collection for suspected MIS-C. 
Section 10.1 (APPENDIX 
1: Schedule of 
Assessments); Table 10: 
Schedule of Assessments  
A footnote was added to clarify the 
blood sample for vaccine 
immunogenicity in Part 1 and Part 2. 
Clarification of subset of 
participants in each Arm that 
will have samples collected for 
immunogenicity postbaseline. 
Section 10.2.18 (Body Mass 
Index Charts for Boys and 
Girls) 
CDC charts based on WHO data for 
use in the US in children < 2 years 
old added for reference. 
Height and weight charts were 
added for use in children < 2 
years of age. 
 

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