A Study of Ad26.COV2.S Administered as Booster Vaccination in Adults Who Have Previously Received Primary Vaccination With Ad26.COV2.S or BNT162b2

Study Overview
=================
Brief Summary
-----------------
The purposes of this study are to demonstrate the non-inferiority (NI) of the neutralizing antibody response to the original strain 14 days after booster vaccination with Ad26.COV2.S at the different dose levels, administered greater than or equal to (>=) 6 months after single-dose primary vaccination with Ad26.COV2.S, compared to the neutralizing antibody response to the original strain induced by single-dose primary vaccination with Ad26.COV2.S; To demonstrate the NI of the neutralizing antibody response to the leading variant of high consequence or concern 14 days after booster vaccination with Ad26.COV2.S at the 5*10^10 virus particle (vp) dose level, administered >= 6 months after single-dose primary vaccination with Ad26.COV2.S (5*10^10 vp dose level), compared to the neutralizing antibody response to the leading variant of high consequence or concern induced by single-dose primary vaccination with Ad26.COV2.S at the 5*10^10 vp dose level, if feasible; To demonstrate the NI of the neutralizing antibody response to the original strain 14 days after booster vaccination with Ad26.COV2.S at the different dose levels administered >=6 months after completing a 2-dose primary vaccination with Pfizer BNT162b2, compared to the neutralizing antibody response to the original strain induced by 2-dose primary vaccination with Pfizer BNT162b2; To demonstrate the NI of neutralizing antibody response to the leading variant of high consequence or concern 14 days after booster vaccination with Ad26.COV2.S at the 5*10^10 vp dose level, administered >= 6 months after completing a 2-dose primary vaccination with Pfizer BNT162b2, compared to the neutralizing antibody response to the leading variant of high consequence or concern induced by 2-dose primary vaccination with Pfizer BNT162b2, if feasible.

Official Title
-----------------
A Randomized, Double-blind, Phase 2 Study to Evaluate the Immunogenicity, Reactogenicity and Safety of Ad26.COV2.S Administered as Booster Vaccination in Adults 18 Years of Age and Older Who Have Previously Received Primary Vaccination With Ad26.COV2.S or BNT162b2

Conditions
-----------------
Coronavirus Disease

Intervention / Treatment
-----------------
* Biological: Ad26.COV2.S


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Cohort 1: Participant received Ad26.COV2.S in VAC31518COV3001. The interval between the Ad26.COV2.S primary vaccination should preferably be greater than or equal to (>=) 6 months prior to study vaccination on VAC31518COV2008, however a window of maximum -20 days is allowed; Cohort 2: Participant completed primary vaccination with a 2-dose regimen of BNT162b2 vaccine. The last dose of BTN162b2 should preferably be >=6 months prior to study vaccination on COV2008, however a window of a maximum of -20 days is allowed Participant must provide consent indicating that he or she understands the purpose, procedures and potential risks and benefits of the study, and is willing to participate in the study Participant agrees to not donate bone marrow, blood, and blood products from the study vaccine administration until 3 months after receiving the study vaccine Participant must be willing to provide verifiable identification, has means to be contacted and to contact the investigator during the study Participant must be able to read, understand, and complete questionnaires in the electronic clinical outcome assessment (eCOA) (that is, the Coronavirus disease (COVID-19) signs and symptoms surveillance question, the e-Diary, and the electronic patient-reported outcomes (ePROs). Participants with visual impairment are eligible for study participation and may have caregiver assistance in completing the eCOA questionnaires Exclusion Criteria: Participant has a clinically significant acute illness (this does not include minor illnesses such as diarrhea or mild upper respiratory tract infection) or temperature >= 38.0 degree Celsius (C) (100.4 degree Fahrenheit [F]) within 24 hours prior to the planned study vaccination; randomization at a later date is permitted at the discretion of the investigator. Please notify the sponsor (or medical monitor) of this decision Participant has a known or suspected allergy or history of anaphylaxis or other serious adverse reactions to vaccines or their excipients (including specifically the excipients of the study vaccine Participant received treatment with immunoglobulins (Ig) in the 3 months or exogenous blood products (autologous blood transfusions are not exclusionary) in the 4 months before the planned administration of the study vaccine or has any plans to receive such treatment during the study Participant has a known history of confirmed severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection Participant has a history of heparin-induced thrombocytopenia or thrombosis in combination with thrombocytopenia Participant has a history of acute polyneuropathy (example. Guillain-Barre syndrome) History of capillary leak syndrome

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Cohort 1: Group 1: Ad26.COV2.S (Dose Level 1)<br>Participants who have previously received primary vaccination with Ad26.COV2.S will receive single intramuscular (IM) injection of Ad26.COV2.S booster vaccination at dose level 1 on Day 1. | Biological: Ad26.COV2.S<br>* Participants will receive IM injection of Ad26.COV2.S.<br>* Other names: VAC31518;|
| Experimental: Cohort 1: Group 2: Ad26.COV2.S (Dose Level 2)<br>Participants who have previously received primary vaccination with Ad26.COV2.S will receive single IM injection of Ad26.COV2.S booster vaccination at dose level 2 on Day 1. | Biological: Ad26.COV2.S<br>* Participants will receive IM injection of Ad26.COV2.S.<br>* Other names: VAC31518;|
| Experimental: Cohort 1: Group 3: Ad26.COV2.S (Dose Level 3)<br>Participants who have previously received primary vaccination with Ad26.COV2.S will receive single IM injection of Ad26.COV2.S booster vaccination at dose level 3 on Day 1. | Biological: Ad26.COV2.S<br>* Participants will receive IM injection of Ad26.COV2.S.<br>* Other names: VAC31518;|
| Experimental: Cohort 2: Group 4: Ad26.COV2.S (Dose Level 1)<br>Participants who have previously received primary vaccination with BNT162b2 will receive single IM injection of Ad26.COV2.S booster vaccination at dose level 1 on Day 1. | Biological: Ad26.COV2.S<br>* Participants will receive IM injection of Ad26.COV2.S.<br>* Other names: VAC31518;|
| Experimental: Cohort 2: Group 5: Ad26.COV2.S (Dose Level 2)<br>Participants who have previously received primary vaccination with BNT162b2 will receive single IM injection of Ad26.COV2.S booster vaccination at dose level 2 on Day 1. | Biological: Ad26.COV2.S<br>* Participants will receive IM injection of Ad26.COV2.S.<br>* Other names: VAC31518;|
| Experimental: Cohort 2: Group 6: Ad26.COV2.S (Dose Level 3)<br>Participants who have previously received primary vaccination with BNT162b2 will receive single IM injection of Ad26.COV2.S booster vaccination at dose level 3 on Day 1. | Biological: Ad26.COV2.S<br>* Participants will receive IM injection of Ad26.COV2.S.<br>* Other names: VAC31518;|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cohort 1: Percentage of Participants With Serological Response Against SARS-CoV-2 Original Strain 14 Days After Ad26.COV2.S Booster Vaccination After Completing Primary Vaccination With Ad26.COV2.S | Percentage of participants with serological response against SARS-CoV-2 original strain (Wuhan, 2019, whole genome sequence) 14 days after Ad26.COV2.S booster vaccination after completing primary vaccination with Ad26.COV2.S was reported. A participant was considered a responder if one or both of the following conditions were satisfied: (1) Pre-booster titer less than (<) lower limit of quantification (LLOQ) and post-booster titer greater than or equal to (>=) 4*LLOQ or (2) Pre-booster titer greater than (>) LLOQ and post-booster titer >=4*pre-booster titer value. | 14 days after Ad26.COV2.S booster vaccination (i.e., on Day 15) | 
| Cohort 1: Geometric Mean Titers (GMTs) of Neutralizing Antibodies Against SARS-CoV-2 Original Strain 14 Days After Ad26.COV2.S Booster Vaccination After Completing Primary Vaccination With Ad26.COV2.S | GMTs of neutralizing antibodies against SARS-CoV-2 original strain 14 days after Ad26.COV2.S booster vaccination after completing primary vaccination with Ad26.COV2.S (5×10^10 vp dose level) were reported. GMT against original strain was assessed by virus neutralization assay (VNA). | 14 days after Ad26.COV2.S booster vaccination (i.e., on Day 15) | 
| Cohort 1: Percentage of Participants With Serological Response Against SARS-CoV-2 Original Strain 28 Days After Primary Vaccination With Ad26.COV2.S | Percentage of participants with serological response against SARS-CoV-2 original strain 28 days after primary vaccination with Ad26.COV2.S (5×10^10 vp dose level) were reported. A participant was considered a responder if one or both of the following conditions were satisfied: (1) Pre-dose titer <LLOQ and post-vaccination titer >=4*LLOQ or (2) Pre-dose titer >LLOQ and post-vaccination titer >=4*pre-dose 1 titer value. | 28 days after primary vaccination with Ad26.COV2.S (Day 29 of study VAC31518COV3001) | 
| Cohort 1: GMTs of Neutralizing Antibodies Against SARS-CoV-2 Original Strain 28 Days After Primary Vaccination With Ad26.COV2.S | GMTs of neutralizing antibodies against SARS-CoV-2 original strain 28 days after primary vaccination with Ad26.COV2.S (5×10^10 vp dose level) were reported. GMT against original strain was assessed by VNA. | 28 days after primary vaccination with Ad26.COV2.S (Day 29 of study VAC31518COV3001) | 
| Cohort 1: Percentage of Participants With Serological Response Against the Delta Variant 14 Days After Ad26.COV2.S Booster Vaccination (5*10^10 vp Dose Level) After Completing Primary Vaccination With Ad26.COV2.S | Percentage of participants with serological response against leading variant of high consequence or concern (delta variant) 14 days after Ad26.COV2.S booster vaccination (5*10^10 vp Dose Level) after completing primary vaccination with Ad26.COV2.S were reported. A participant was considered a responder if one or both of the following conditions were satisfied: (1) Pre-booster titer <LLOQ and post-booster titer >=4*LLOQ or (2) Pre-booster titer >LLOQ and post-booster titer >=4*pre-booster titer value. As specified in the protocol, data for this outcome measure was not collected and analyzed for Cohort 1: Ad26.COV2.S 2.5*10^10 vp and 1*10^10 vp participants. | 14 days after Ad26.COV2.S booster vaccination (i.e., On Day 15) | 
| Cohort 1: GMTs of Neutralizing Antibodies Against the Leading Variant of High Consequence or Concern (Delta Variant) 14 Days After Ad26.COV2.S Booster Vaccination (5*10^10 vp Dose Level) After Completing Primary Vaccination With Ad26.COV2.S | GMTs of neutralizing antibodies against leading variant of high consequence or concern (delta variant) 14 days After Ad26.COV2.S booster vaccination (5*10^10 vp dose level) after completing primary vaccination with Ad26.COV2.S were reported. GMT against Delta Variant was assessed by VNA. As specified in the protocol, data for this outcome measure was not collected and analyzed for Cohort 1: Ad26.COV2.S 2.5*10^10 vp and 1*10^10 vp participants. | 14 days after Ad26.COV2.S booster vaccination (i.e., On Day 15) | 
| Cohort 1: Percentage of Participants With Serological Response Against SARS-CoV-2 Leading Variant of High Consequence or Concern (Delta Variant) 28 Days After Primary Vaccination With Ad26.COV2.S | Percentage of participants with serological response against SARS-CoV-2 leading variant of high consequence or concern (delta variant) 28 days after primary vaccination with Ad26.COV2.S (5*10^10 vp dose level) were reported. A participant was considered a responder if one or both of the following conditions were satisfied: (1) Pre-dose titer <LLOQ and post-vaccination titer >=4*LLOQ or (2) Pre-dose titer >LLOQ and post-vaccination titer >=4*pre-dose 1 titer value. As specified in the protocol, data for this outcome measure was not collected and analyzed for Cohort 1: Ad26.COV2.S 2.5*10^10 vp and 1*10^10 vp participants. | 28 days after primary vaccination with Ad26.COV2.S (Day 29 of study VAC31518COV3001) | 
| Cohort 1: GMTs of Neutralizing Antibodies Against the Leading Variant of High Consequence or Concern (Delta Variant) 28 Days After Primary Vaccination With Ad26.COV2.S (5*10^10 vp Dose Level) | GMTs of neutralizing antibodies against the leading variant of high consequence or concern (delta variant) 28 days after primary vaccination with Ad26.COV2.S (5*10^10 vp dose level) were reported. GMT against Delta variant was assessed by VNA. As specified in the protocol, data for this outcome measure was not collected and analyzed for Cohort 1: Ad26.COV2.S 2.5*10^10 vp and 1*10^10 vp participants. Lower limit of Quantification (LLOQ) was 65. | 28 days after primary vaccination with Ad26.COV2.S (Day 29 of study VAC31518COV3001) | 
| Cohort 2: Percentage of Participants With Serological Response Against SARS-CoV-2 Original Strain, 14 Days After Ad26.COV2.S Booster Vaccination After Completing 2-dose Primary Vaccination With BNT162b2 | Percentage of participants with serological response against SARS-CoV-2 original strain, 14 days after Ad26.COV2.S booster vaccination after completing 2-dose primary vaccination with BNT162b2 were reported. A participant was considered a responder if at least one of the following conditions were satisfied: (1) If pre-booster 1 titer <LLOQ, then post-booster titer >=4*LLOQ or (2) If pre-booster 1 titer >LLOQ, then post-booster titer >=4*pre-booster value (titer). | 14 days after Ad26.COV2.S booster vaccination (i.e., On Day 15) | 
| Cohort 2: GMTs of Neutralizing Antibodies Against SARS-CoV-2 Original Strain 14 Days After Ad26.COV2.S Booster Vaccination After Completing 2-dose Primary Vaccination With BNT162b2 | GMTs of neutralizing antibodies against SARS-CoV-2 original strain 14 days after Ad26.COV2.S booster vaccination after completing 2-dose primary vaccination with BNT162b2 were reported. GMT against original strain was assessed by VNA. | 14 days after Ad26.COV2.S booster vaccination (i.e., On Day 15) | 
| Cohort 2: Percentage of Participants With Serological Response Against SARS-CoV-2 Original Strain 2 Weeks to 2 Months After Completing 2-dose Primary Vaccination With BNT162b2 (Pfizer BNT162b2 External Samples) | Percentage of participants with serological response against SARS-CoV-2 original strain 2 weeks to 2 months after completing 2-dose primary vaccination with BNT162b2 were planned to be reported. A participant was considered a responder if at least one of the following conditions were satisfied: (1) If pre-dose 1 titer <LLOQ, then post-vaccination titer >=4*LLOQ. (2) If pre-dose 1 titer >LLOQ, then post-vaccination titer >=4*pre-dose 1 value (titer). | 2 weeks to 2 months after primary vaccination with BNT162b2 (up to 1.5 months) | 
| Cohort 2: GMTs of Neutralizing Antibodies Against SARS-CoV-2 Original Strain 2 Weeks to 2 Months After Completing 2-dose Primary Vaccination With BNT162b2 (Pfizer BNT162b2 External Samples) | GMTs of neutralizing antibodies against SARS-CoV-2 original strain 2 weeks to 2 months after completing 2-dose primary vaccination with BNT162b2 were reported. GMT against original strain was assessed by VNA. | 2 weeks to 2 months after primary vaccination with BNT162b2 (up to 1.5 months) | 
| Cohort 2: Percentage of Participants With Serological Response Against SARS-CoV-2 Delta Variant 14 Days After Booster Vaccination (5*10^10 vp Dose Level) After Completing 2-dose Primary Vaccination With BNT162b2 | Percentage of participants with serological response against SARS-CoV-2 leading variant of high consequence or concern (Delta) 14 days after booster vaccination (5*10^10 vp dose level) after completing 2-dose primary vaccination with BNT162b2 were reported. A participant was considered a responder if at least one of the following conditions was satisfied: (1) If pre-booster 1 titer <LLOQ, then post-booster titer >=4*LLOQ or (2) If pre-booster 1 titer >LLOQ, then post-booster titer >=4*pre-booster value (titer). As specified in the protocol, data for this outcome measure was not collected and analyzed for Cohort 2: Ad26.COV2.S 2.5*10^10 vp and 1*10^10 vp participants. | 14 days after Ad26.COV2.S booster vaccination (i.e., On Day 15) | 
| Cohort 2: GMTs of Neutralizing Antibodies Against the SARS-CoV-2 Leading Variant of High Consequence or Concern (Delta Variant) 14 Days After Booster Vaccination (5*10^10 vp Dose Level) After Completing 2-dose Primary Vaccination With BNT162b2 | Antibody GMTs of neutralizing antibodies against the SARS-CoV-2 leading variant of high consequence or concern (Delta variant) 14 days after booster vaccination after completing 2-dose primary vaccination with BNT162b2 were reported. GMT against delta variant was assessed by VNA. As specified in the protocol, data for this outcome measure was not collected and analyzed for Cohort 2: Ad26.COV2.S 2.5*10^10 vp and 1*10^10 vp participants. | 14 days after Ad26.COV2.S booster vaccination (i.e., On Day 15) | 
| Cohort 2: Percentage of Participants With Seropositive Response to Vaccination Against the SARS-CoV-2 Delta Variant 2 Weeks to 2 Months After Completing Primary Vaccination With 2-dose BNT162b2 (Pfizer BNT162b2 External Samples) | Percentage of participants with seropositive response to vaccination against the SARS-CoV-2 leading variant of high consequence or concern (Delta) 2 weeks to 2 months after completing primary vaccination with 2-dose BNT162b2 were planned to be reported. A participant was considered a responder if one or both of the following conditions was satisfied: (1) Pre-dose titer <LLOQ and post-vaccination titer >=4*LLOQ. or (2) Pre-dose titer >LLOQ and post-vaccination titer >=4*pre-dose 1 titer value. | 2 weeks to 2 months after primary vaccination with BNT162b2 (up to 1.5 months) | 
| Cohort 2: GMTs of Neutralizing Antibodies Against the SARS-CoV-2 Delta Variant 2 Weeks to 2 Months After Completing 2-dose Primary Vaccination With BNT162b2 (Pfizer BNT162b2 External Samples) | Antibody GMTs of neutralizing antibodies against the SARS-CoV-2 leading variant of high consequence or concern (Delta variant) 2 weeks to 2 months after completing 2-dose primary vaccination with BNT162b2 were reported. GMT against delta variant was assessed by VNA. | 2 weeks to 2 months after primary vaccination with BNT162b2 (up to 1.5 months) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cohorts 1 and 2: Number of Participants With Solicited Local Adverse Events (AEs) After Ad26.COV2.S Booster Vaccination | Participants who received the booster dose were asked to note the occurrence of injection site pain, erythema, and swelling at the study vaccine injection site in e-Diary daily for 7 days post-booster vaccination (day of vaccination and the subsequent 7 days). | Up to 7 days after booster vaccination (Up to Day 8) | 
| Cohorts 1 and 2: Number of Participants With Solicited Systemic AEs After Ad26.COV2.S Booster Vaccination | Participants recorded the temperature in the e-Diary in the evening of the day of vaccination, and then daily for the next 7 days approximately at the same time each day. If more than 1 measurement was made on any given day, the highest temperature of that day was recorded in the e-Diary. Fever was defined as endogenous elevation of body temperature >= 38.0 degree Celsius or >=100.4-degree Fahrenheit, as recorded in at least 1 measurement. Participants also noted the signs and symptoms in the e-Diary on a daily basis for 7 days post-booster vaccination (day of vaccination and the subsequent 7 days), if feasible, for the following events: fatigue, headache, nausea, myalgia. | Up to 7 days after booster vaccination (Up to Day 8) | 
| Cohorts 1 and 2: Number of Participants With Unsolicited AEs After Ad26.COV2.S Booster Vaccination | Unsolicited AEs were all AEs for which the participant was not specifically questioned in the participant diary. | Up to 28 days after booster vaccination (Up to Day 29) | 
| Cohorts 1 and 2: Number of Participants With Serious Adverse Events (SAEs) After Ad26.COV2.S Booster Vaccination | SAE is any untoward medical occurrence that at any dose may result in death, is life-threatening, requires inpatient hospitalization or prolongation of existing hospitalization, results in persistent or significant disability/incapacity, is a congenital anomaly/birth defect, is a suspected transmission of any infectious agent via a medicinal product. | From booster vaccination (Day 1) until 1 year post booster vaccination | 
| Cohorts 1 and 2: Number of Participants With Adverse Events of Special Interest (AESIs) After Ad26.COV2.S Booster Vaccination | Number of participants with AESIs were reported. AESIs are significant AEs that are judged to be of special interest because of clinical importance, known or suspected class effects, or based on nonclinical signals. | From booster vaccination (Day 1) until 1 year post booster vaccination | 
| Cohort 1: Percentage of Participants With Serological Response Against SARS-CoV-2 Original Strain, Delta, and Beta Variant 14 Days After Ad26.COV2.S Booster Vaccination After Primary Vaccination With Ad26.COV2.S | Percentage of participants with serological response against SARS-CoV-2 original strain, leading variant of high consequence or concern (delta variant), and other relevant variant of concern (beta variant) 14 days after Ad26.COV2.S booster vaccination after primary vaccination with Ad26.COV2.S were reported. A participant was considered a responder if at least one of the following conditions were satisfied: (1) If pre-booster 1 titer <LLOQ, then post-booster titer >=4*LLOQ or (2) If pre-booster 1 titer >LLOQ, then post-booster titer >=4*pre-booster value (titer). | 14 days after Ad26.COV2.S booster vaccination (i.e., On Day 15) | 
| Cohort 1: Percentage of Participants With Serological Response Against SARS-CoV-2 Leading Variant of High Consequence or Concern (Omicron Variant) 14 Days After Ad26.COV2.S Booster Vaccination After Primary Vaccination With Ad26.COV2.S | Percentage of participants with serological response against SARS-CoV-2 leading variant of high consequence or concern (omicron variant) 14 days after Ad26.COV2.S booster vaccination after primary vaccination with Ad26.COV2.S were reported. | 14 days after Ad26.COV2.S booster vaccination (i.e., On Day 15) | 
| Cohort 1: GMTs of Neutralizing Antibodies Against the Original Strain, Delta and Beta Strain 14 Days After Ad26.COV2.S Booster Vaccination | GMTs of neutralizing antibodies against the original strain, leading variant of high consequence or concern (delta variant), and other relevant variant of concern (beta variant) 14 days after Ad26.COV2.S booster vaccination were reported. GMT against original strain was assessed by VNA. | 14 days after Ad26.COV2.S booster vaccination (i.e., On Day 15) | 
| Cohort 1: GMTs of Neutralizing Antibodies Against the Leading Variant of High Consequence or Concern (Omicron Variant) 14 Days After Ad26.COV2.S Booster Vaccination | GMTs of neutralizing antibodies against the leading variant of high consequence or concern (omicron variant) 14 days after Ad26.COV2.S booster vaccination were reported. | 14 days after Ad26.COV2.S booster vaccination (i.e., On Day 15) | 
| Cohort 1: Percentage of Participants With Serological Response Against SARS-CoV-2 Original Strain, Delta, and Beta Variant 28 Days After Ad26.COV2.S Booster Vaccination After Primary Vaccination With Ad26.COV2.S | Percentage of participants with serological response against SARS-CoV-2 original strain, leading variant of high consequence or concern (delta variant), and other relevant variant of concern (beta variant) 28 days after Ad26.COV2.S booster vaccination after primary vaccination with Ad26.COV2.S were reported. A participant was considered a responder if at least one of the following conditions were satisfied: (1) If pre-booster 1 titer <LLOQ, then post-booster titer >=4*LLOQ or (2) If pre-booster 1 titer >LLOQ, then post-booster titer >=4*pre-booster value (titer). | 28 days after Ad26.COV2.S booster vaccination (i.e., On Day 29) | 
| Cohort 1: Percentage of Participants With Serological Response Against SARS-CoV-2 Leading Variant of High Consequence or Concern (Omicron Variant) 28 Days After Ad26.COV2.S Booster Vaccination After Primary Vaccination With Ad26.COV2.S | Percentage of participants with serological response against SARS-CoV-2 leading variant of high consequence or concern (omicron variant) 28 days after Ad26.COV2.S booster vaccination after primary vaccination with Ad26.COV2.S were reported. | 28 days after Ad26.COV2.S booster vaccination (i.e., On Day 29) | 
| Cohort 1: GMTs of Neutralizing Antibodies Against the Original Strain, Delta and Beta Strain 28 Days After Ad26.COV2.S Booster Vaccination | GMTs of neutralizing antibodies against the original strain, leading variant of high consequence or concern (delta variant), and other relevant variant of concern (beta variant) 28 days after Ad26.COV2.S booster vaccination were reported. GMT was assessed by VNA. | 28 days after Ad26.COV2.S booster vaccination (i.e., On Day 29) | 
| Cohort 1: GMTs of Neutralizing Antibodies Against the Leading Variant of High Consequence or Concern (Omicron Variant) 28 Days After Ad26.COV2.S Booster Vaccination | GMTs of neutralizing antibodies against the leading variant of high consequence or concern (omicron variant) 28 days after Ad26.COV2.S booster vaccination were reported. | 28 days after Ad26.COV2.S booster vaccination (i.e., On Day 29) | 
| Cohort 1: Percentage of Participants With Antibodies Binding to SARS-CoV-2 Relevant Variants of Concern or Individual SARS-CoV-2 Proteins by Enzyme-linked Immunosorbent Assay (ELISA) | Percentage of participants with antibodies binding to SARS-CoV-2 relevant variants of concern or individual SARS-CoV-2 Proteins by ELISA were planned to be reported. | 28 days after Ad26.COV2.S booster vaccination (i.e., On Day 29) | 
| Cohort 1: Number of Participants With Antibodies Binding to SARS-CoV-2 Relevant Variants of Concern or Individual SARS-CoV-2 Proteins by Meso Scale Discovery (MSD) | Number of participants with antibodies binding to SARS-CoV-2 relevant variants of concern or individual SARS-CoV-2 Proteins by MSD were planned to be reported. | From booster vaccination (Day 1) until 1 year from booster vaccination | 
| Cohort 2: Percentage of Participants With Serological Response to Vaccination Against the Original Strain, Delta and Beta Variant 14 Days After Ad26.COV2.S Booster Vaccination After Primary Vaccination With BNT162b2 | Percentage of participants with serological response to vaccination against the original strain, leading variant of high consequence or concern (delta variant), and other relevant variant of concern (beta variant) 14 days after Ad26.COV2.S booster vaccination after primary vaccination with BNT162b2 were reported. A participant was considered a responder if at least one of the following conditions was satisfied: (1) If pre-booster 1 titer <LLOQ, then post-booster titer >=4*LLOQ or (2) If pre-booster 1 titer >LLOQ, then post-booster titer >=4*pre-booster value (titer). | 14 days after Ad26.COV2.S booster vaccination (i.e., On Day 15) | 
| Cohort 2: Percentage of Participants With Serological Response to Vaccination Against the Leading Variant of High Consequence or Concern (Omicron Variant) 14 Days After Ad26.COV2.S Booster Vaccination After Primary Vaccination With BNT162b2 | Percentage of participants with serological response to vaccination against the leading variant of high consequence or concern (omicron variant) 14 days after Ad26.COV2.S booster vaccination after primary vaccination with BNT162b2 was reported. | 14 days after Ad26.COV2.S booster vaccination (i.e., On Day 15) | 
| Cohort 2: Antibody GMTs of Neutralizing Antibodies Against the Original Strain, Delta and Beta Variant 14 Days After Ad26.COV2.S Booster Vaccination After Completing Primary Vaccination With BNT162b2 | Antibody GMTs of neutralizing antibodies against the original strain, leading variant of high consequence or concern (delta variant), and other relevant variant of concern (beta variant) 14 days after Ad26.COV2.S booster vaccination after completing primary vaccination with BNT162b2 were reported. | 14 days after Ad26.COV2.S booster vaccination (i.e., On Day 15) | 
| Cohort 2: Antibody GMTs of Neutralizing Antibodies Against the Leading Variant of High Consequence or Concern (Omicron Variant) 14 Days After Ad26.COV2.S Booster Vaccination After Completing Primary Vaccination With BNT162b2 | Antibody GMTs of neutralizing antibodies against the leading variant of high consequence or concern (omicron variant) 14 days after Ad26.COV2.S booster vaccination after completing primary vaccination with BNT162b2 were reported. | 14 days after Ad26.COV2.S booster vaccination (i.e., On Day 15) | 
| Cohort 2: Percentage of Participants With Serological Response to Vaccination Against the Original Strain, Delta and Beta Variant 28 Days After Ad26.COV2.S Booster Vaccination After Primary Vaccination With BNT162b2 | Percentage of participants with serological response to vaccination against the original strain, leading variant of high consequence or concern (delta variant), and other relevant variant of concern (Beta variant) 28 days after Ad26.COV2.S booster vaccination after primary vaccination with BNT162b2 were reported. A participant was considered a responder if at least one of the following conditions was satisfied: (1) If pre-booster 1 titer <LLOQ, then post-booster titer >=4*LLOQ or (2) If pre-booster 1 titer >LLOQ, then post-booster titer >=4*pre-booster value (titer). | 28 days after Ad26.COV2.S booster vaccination (i.e., On Day 29) | 
| Cohort 2: Percentage of Participants With Serological Response to Vaccination Against the Leading Variant of High Consequence or Concern (Omicron Variant) 28 Days After Ad26.COV2.S Booster Vaccination After Primary Vaccination With BNT162b2 | Percentage of participants with serological response to vaccination against the leading variant of high consequence or concern (omicron variant) 28 days after Ad26.COV2.S booster vaccination after primary vaccination with BNT162b were reported. | 28 days after Ad26.COV2.S booster vaccination (i.e., On Day 29) | 
| Cohort 2: GMTs of Neutralizing Antibodies Against the Original Strain, Delta and Beta Strain 28 Days After Ad26.COV2.S Booster Vaccination After Completing Primary Vaccination With BNT162b2 | GMTs of neutralizing antibodies against the original strain, leading variant of high consequence or concern (delta variant), and other relevant variant of concern (beta variant) 28 days after Ad26.COV2.S booster vaccination after completing primary vaccination with BNT162b2 were reported. | 28 days after Ad26.COV2.S booster vaccination (i.e., On Day 29) | 
| Cohort 2: GMTs of Neutralizing Antibodies Against the Leading Variant of High Consequence or Concern (Omicron Variant) 28 Days After Ad26.COV2.S Booster Vaccination After Completing Primary Vaccination With BNT162b2 | GMTs of neutralizing antibodies against the leading variant of high consequence or concern (omicron variant) 28 days after Ad26.COV2.S booster vaccination after completing primary vaccination with BNT162b2 were reported. | 28 days after Ad26.COV2.S booster vaccination (i.e., On Day 29) | 
| Cohort 2: Percentage of Participants With Antibodies Binding to SARS-CoV-2 Relevant Variants of Concern or Individual SARS-CoV- 2 Proteins by ELISA | Percentage of participants with antibodies binding to SARS-CoV-2 relevant variants of concern or individual SARS-CoV- 2 proteins by ELISA were planned to be reported. | 28 days after Ad26.COV2.S booster vaccination (i.e., On Day 29) | 
| Cohort 2: Number of Participants With Antibodies Binding to SARS-CoV-2 Relevant Variants of Concern or Individual SARS-CoV- 2 Proteins by MSD | Number of participants with antibodies binding to SARS-CoV-2 relevant variants of concern or individual SARS-CoV- 2 proteins by MSD were planned to be reported. | From booster vaccination (Day 1) until 1 year from booster vaccination | 
| Cohorts 1 and 2: Number of Participants With Antibodies Binding to the SARS-CoV-2 Nucleocapsid (N) Protein at Day 1 as Assessed by N-Serology | Number of participants with antibodies binding to the SARS-CoV-2 nucleocapsid (N) protein at Day 1 as assessed by N-serology were planned to be reported. | Day 1 |