cdc.gov/coronavirus

Safety update of 1st booster mRNA 

COVID-19 vaccination

Advisory Committee on Immunization Practices 

(ACIP)

April 20, 2022

Nicola Klein, MD, PhD

Kaiser Permanente Vaccine Study Center

Kaiser Permanente Northern California

Tom Shimabukuro, MD, MPH, MBA

Vaccine Safety Team

CDC COVID-19 Vaccine Task Force
Safety Surveillance of 1st Booster Doses in the Vaccine 

Safety Datalink

Nicola Klein, MD, PhD

Kaiser Permanente Vaccine Study Center

Kaiser Permanente Northern California
Vaccine Safety Datalink (VSD)

• Established in 1990

• Collaborative project between CDC and 9 integrated healthcare organizations

• Includes ~ 12 million individuals across all sites 3
VSD 1st Boosters by Primary Series Vaccination

Data Through April 9th, 2022

4
VSD 1st Booster Dose by Demographics

5
VSD Rapid Cycle Analysis (RCA) for Boosters

• Pre-specified surveillance outcomes were assessed during weekly 

sequential monitoring after 1st COVID-19 booster vaccination*

‒ Analyses assess the risk of pre-specified outcomes within 1–21 days following a booster 

vaccination compared with boosted individuals who are within 22–42 days following the 

booster dose, adjusting for age, sex, race/ethnicity, VSD site, time since primary series, 

and calendar time.

‒ Weekly sequential analyses will continue through 2022, with a one-sided p-value 

threshold for signaling of 0.01.

‒ Due to the association of myocarditis/pericarditis with primary mRNA vaccination, 

myocarditis/pericarditis cases after the 1st booster were also chart reviewed and 

adjudicated using the CDC case definitions.

6

*Rapid Cycle Analysis (RCA) to monitor the safety of COVID-19 vaccines in near real-time within the Vaccine Safety Datalink. 

Available at https://www.cdc.gov/vaccinesafety/pdf/COVID19-RCA-Protocol-1342-508.pdf
Vaccinee with Outcome in the Risk Interval and a Concurrent Comparator

“Boosted Individuals Only”

On each calendar day that an outcome occurred 

in a vaccinee (e.g., June 3), we compared 

vaccinees in their risk interval (day 1–21) with 

similar vaccinees in their comparison interval (day 

22–42)

By similar, we mean they were in the same age 

group and of the same sex, race, and at the same 

VSD site

Comparison Interval 22–42 days post-vaccination 

22 June 3 42

Vaccinated with Booster 

May 3

1

Risk Interval 1–21 days post-vaccination

21 June 3

Vaccinated with 

Booster May 30

7
Signals for Pre-specified Outcomes in 21-day Risk Interval Through 4/12/22

Primary series with Pfizer - Pfizer OR 

Moderna - Moderna

Pfizer -

Pfizer

Moderna -

Moderna

Janssen

Signal after 1st Booster Pfizer OR Moderna Pfizer Moderna Pfizer Moderna Janssen

Outcome Event Signal?

Acute myocardial infarction No No No No No No

Appendicitis No No No No No No

Bell's palsy No No No No No No

Cerebral venous sinus thrombosis No No No - - No

Disseminated intravascular coagulation No No No No - No

Encephalitis / myelitis / encephalomyelitis No No No - - -

Guillain-Barre syndrome No No No No - No

Stroke, hemorrhagic No No No No No No

Stroke, ischemic No No No No No No

Immune thrombocytopenia No No No No No -

Myocarditis / pericarditis Yes No No No No No

Seizures No No No No No No

Transverse myelitis No No No - - -

Thrombotic thrombocytopenic purpura No No No - - No

Thrombosis with thrombocytopenia syndrome No No No - No -

Venous thromboembolism No No No No No No

Pulmonary embolism No No No No No No

8 “-” indicates that analyses are not yet possible. 
VSD COVID-19 RCA

1st Booster Dose 

Myocarditis and Pericarditis –

Preliminary Chart Review Analysis

9
Myocarditis and Pericarditis: Electronic 

Case Identification using ICD-10 Codes1

Code List (based on consultation with cardiologist)

• B33.22 Viral myocarditis

• B33.23 Viral pericarditis

• I30.* Acute pericarditis

• I40.* Acute myocarditis

• I51.4 Myocarditis, unspecified

• I31.9 Disease of the pericardium, unspecified

10

1Case definition excludes individuals with COVID-19 infection <30 days before 

myocarditis/pericarditis diagnosis. 

* Includes all subcodes.
Chart Review Summary: Myocarditis and Pericarditis 

after a 1st mRNA COVID-19 Booster Vaccine

• All electronically-identified cases among all ages up to 98 days post 

vaccination are being chart-reviewed.

• Chart review is completed for 271 cases through March (25 potential 

cases pending). 

• Adjudicators verified 139/271 (51%) myocarditis/pericarditis cases.

• 12–39 years old: 53/68 (78%)

• 40+ years old: 86/203 (42%)

11
Chart Review Summary: Verified Myocarditis and 

Pericarditis cases after a 1st Booster Vaccine

12

12–39 year olds 40+ year olds

Case verification (anytime after vaccination) 53/68 (78%) 86/203 (42%)

Male sex 38/53 (72%) 51/86 (59%)

History of COVID (>30 days prior to diagnosis) 10/53 (19%) 11/86 (13%)

History of myocarditis/pericarditis 2/53 (4%) 4/86 (5%)

Median age 25 years 68.5 years

Median time from vaccination to symptom onset 4 days 29.5 days

Adjudication diagnosis

Myocarditis 12/53 (23%) 12/86 (14%)

Pericarditis 12/53 (23%) 57/86 (66%)

Myopericarditis 29/53 (55%) 17/86 (20%)
Timing of Symptom Onset after 1st Booster: 53 Verified 

Myocarditis and Pericarditis Cases in 12–39-Year-Olds

13
Timing of Symptom Onset after 1st Booster: 86 Verified 

Myocarditis and Pericarditis Cases in 40+ year-olds

14
1Comparison interval is 22–42 days after booster dose. 2Adjusted for VSD site, 5-year age group, sex, race/ethnicity, calendar date, and time since primary series.

3“Either” includes heterologous and homologous primary -> booster doses. Product specific analyses include only homologous primary->booster doses. 

4Two additional cases were in the risk interval but were not included because there were no appropriate comparators. These cases are included in the events/million dose calculation.

Analysis

Ages Vaccine

Events 

in Risk

Interval

Events in 

Comparison 

Interval1

Adjusted 

Rate Ratio2

95%

Confidence

Interval

2-Sided

P-value

Events/Million 

Doses

1st

Booster3

12–39 Either 28 10 4.89 2.24 – 11.31 <0.001 20.3 (13.5 – 29.3)

12–39 Pfizer 18 6 5.14 1.86 – 15.90 0.001 21.4 (12.7 – 33.8)

12–39 Moderna4 5 3 3.64 0.79 – 19.45 0.097 17.0 (6.8 – 35.0)

Verified Myocarditis and Pericarditis in the 0–7 Day Risk Interval

Compared with Events on the Same Calendar Days Among Primary Series and Boosted Comparators

15
1Comparison interval is 22–42 days after booster dose.

2Adjusted for VSD site, 5-year age group, sex, race/ethnicity, calendar date, and time since primary series.

3“Either” includes heterologous and homologous primary -> booster doses. Product specific analyses include only homologous primary-> booster doses. 

4Two additional cases were in the risk interval but were not included because there were no appropriate comparators. These cases are included in the events/million dose calculation.

5One additional case was in the risk interval but not included because there were no appropriate comparators. This case is included in the events/million dose calculation.

Analysis

Ages Vaccine Events in Risk

Interval

Events in 

Comparison 

Interval1

Adjusted 

Rate Ratio2

95%

Confidence

Interval

2-Sided

P-value

Events/Million 

Doses

Primary, 

Dose 2

12–39 Either 112 14 24.38 14.00 – 44.96 <0.001 38.2 (31.5 – 45.9)

12–39 Pfizer 83 10 28.07 14.63 – 58.50 <0.001 41.4 (33.1 – 51.1)

12–39 Moderna 28 3 24.49 7.82 – 105.14 <0.001 30.8 (20.5 – 44.5)

1st

Booster3

12–39 Either 28 10 4.89 2.24 – 11.31 <0.001 20.3 (13.5 – 29.3)

12–39 Pfizer 18 6 5.14 1.86 – 15.90 0.001 21.4 (12.7 – 33.8)

12–39 Moderna4 5 3 3.64 0.79 – 19.45 0.097 17.0 (6.8 – 35.0)

Verified Myocarditis and Pericarditis in the 0–7 Day Risk Interval

Compared with Events on the Same Calendar Days Among Primary Series and Boosted Comparators

16
1Comparison interval is 22–42 days after booster dose.

2Adjusted for VSD site, 5-year age group, sex, race/ethnicity, calendar date, and time since primary series.

3“Either” includes heterologous and homologous primary -> booster doses. Product specific analyses include only homologous primary->booster doses. 

4Two additional cases were in the risk interval but were not included because there were no appropriate comparators. These cases are included in the events/million dose calculation.

5One additional case was in the risk interval but not included because there were no appropriate comparators. This case is included in the events/million dose calculation.

Analysis

Ages Vaccine

Events 

in Risk

Interval

Events in 

Comparison 

Interval1

Adjusted 

Rate Ratio2

95%

Confidence

Interval

2-Sided

P-value

Events/Million 

Doses

1st

Booster3

12–39 Either 28 10 4.89 2.24 – 11.31 <0.001 20.3 (13.5 – 29.3)

12–39 Pfizer 18 6 5.14 1.86 – 15.90 0.001 21.4 (12.7 – 33.8)

12–39 Moderna4 5 3 3.64 0.79 – 19.45 0.097 17.0 (6.8 – 35.0)

40+ Either 5 11 15 2.30 0.95 – 5.43 0.063 4.0 (2.1 – 7.0)

40+ Pfizer5 4 5 1.65 0.34 – 7.31 0.509 3.3 (1.1 – 7.6)

40+ Moderna4 4 8 1.85 0.43 – 6.85 0.373 4.6 (1.7 – 10.1)

17

Verified Myocarditis and Pericarditis in the 0–7 Day Risk Interval

Compared with Events on the Same Calendar Days Among Primary Series and Boosted Comparators
1Comparison interval is 22–42 days after booster dose.

2Adjusted for VSD site, 5-year age group, sex, race/ethnicity, calendar date, and time since primary series.

3“Either” includes heterologous and homologous primary -> booster doses. Product specific analyses include only homologous primary-> booster doses. 

4Two additional cases were in the risk interval but were not included because there were no appropriate comparators. These cases are included in the events/million dose calculation.

Analysis

Ages Vaccine

Events 

in Risk

Interval

Events in 

Comparison 

Interval1

Adjusted 

Rate Ratio2

95%

Confidence

Interval

2-Sided

P-value

Events/Million 

Doses

1st

Booster3

12–39 Either 30 10 1.90 0.91 – 4.25 0.092 21.9 (14.8 – 31.2)

12–39 Pfizer 19 6 2.07 0.79 – 6.05 0.146 22.8 (13.7 – 35.6)

12–39 Moderna4 6 3 1.36 0.33 – 6.87 0.697 19.5 (8.4 – 38.5)

Verified Myocarditis and Pericarditis in the 0–21 Day Risk Interval

Compared with Events on the Same Calendar Days Among Primary Series and Boosted Comparators

18
1Comparison interval is 22–42 days after booster dose.

2Adjusted for VSD site, 5-year age group, sex, race/ethnicity, calendar date, and time since primary series. 

3“Either” includes heterologous and homologous primary -> booster doses. Product specific analyses include only homologous primary-> booster doses. 

4Two additional cases were in the risk interval but were not included because there were no appropriate comparators. These cases are included in the events/million dose calculation.

5Four additional cases were in the risk interval but not included because there were no appropriate comparators. These cases are included in the events/million dose calculation.

6Three additional cases were in the risk interval but not included because there were no appropriate comparators. These cases are included in the events/million dose calculation.

Analysis

Ages Vaccine

Events 

in Risk

Interval

Events in 

Comparison 

Interval1

Adjusted 

Rate Ratio2

95%

Confidence

Interval

2-Sided

P-value

Events/Million 

Doses

1st

Booster3

12–39 Either 30 10 1.90 0.91 – 4.25 0.092 21.9 (14.8 – 31.2)

12–39 Pfizer 19 6 2.07 0.79 – 6.05 0.146 22.8 (13.7 – 35.6)

12–39 Moderna4 6 3 1.36 0.33 – 6.87 0.697 19.5 (8.4 – 38.5)

40+ Either5 29 15 1.96 1.02 – 3.88 0.044 11.0 (7.5 – 15.4)

40+ Pfizer5 15 5 3.01 1.06 – 9.68 0.038 12.5 (7.5 – 19.5)

40+ Moderna6 9 8 1.28 0.42 – 3.80 0.650 9.3 (4.8 – 16.3)

Verified Myocarditis and Pericarditis in the 0–21 Day Risk Interval

Compared with Events on the Same Calendar Days Among Primary Series and Boosted Comparators

19
Summary: Preliminary Findings of RCA Monitoring for 1st

Boosters 

• In weekly surveillance, the only safety signal has been for myocarditis/pericarditis 

in the 21 days after a 1st booster dose.

• No other safety signals in weekly monitoring of pre-specified outcomes. 

• Myocarditis/pericarditis differed between persons ages 12–39 and 40+ years. 

• 12–39 years: mostly myocarditis and myopericarditis with onset <7 days after 1st booster.

• 40+ years: mostly pericarditis; cases more spread out in the 3 weeks after 1st booster.

• For persons ages 12–39 years, rate ratios for myocarditis/pericarditis 0–7 days 

after 1st booster dose were elevated.

• Rate per million 1st booster doses administered was not higher than after primary series dose 

2 mRNA COVID-19 vaccination. 

• For persons ages 40 years and older, rate ratios for myocarditis/pericarditis were 

elevated, but less so, in the 0–7 and 0–21 days after the 1st booster dose 

compared with persons ages 12–39 years.

• Surveillance is ongoing. 20
cdc.gov/coronavirus

Safety update of 1st booster mRNA 

COVID-19 vaccination

Vaccine Adverse Event Reporting System (VAERS)

&

V-safe

Tom Shimabukuro, MD, MPH, MBA

Vaccine Safety Team

CDC COVID-19 Vaccine Task Force
+ co-managed by

CDC and FDA

Vaccine Adverse Event 

Reporting System

http://vaers.hhs.gov

VAERS is the nation’s early warning system for vaccine safety

22
VAERS accepts reports from everyone

Key strengths

 Rapidly detects potential 

safety problems 

 Can detect rare adverse 

events

Key limitations

 Passive surveillance system

 Inconsistent quality and 

completeness of information

 Reporting biases

 Generally, cannot determine 

cause and effect

Regardless of the plausibility of the vaccine causing the event or the 

clinical seriousness of the event

23
U.S. reports to VAERS following 1st booster mRNA COVID-19 

vaccination* (as of April 11, 2022) 

24

* Among persons receiving Pfizer-BioNTech dose 3: children and adolescents ages 12–15 years vaccinated during Jan 3 – April 11, 2022, and ages 16–17 years vaccinated during Dec 9, 2021 –

April 11, 2022; adults ages ≥18 years vaccinated during September 22, 2021 – April 11, 2022. Among persons receiving Moderna booster doses, adults ages ≥18 years vaccinated during October 

20, 2021 – April 11, 2022. All reports received and processed as of April 11, 2022. 

† Doses of Pfizer-BioNTech dose 3 administered among children and adolescents ages 12–15 years during January 6 – Apr 14, 2022; adolescents ages 16–17 years during Dec 9, 2021 – April 14, 

2022; adults ages ≥18 years during September 22, 2021 – April 14, 2022. Doses of Moderna dose 3 administered among adults ages ≥18 years during October 28, 2021 – April 14, 2022

‡ Sex was not reported in approximately 2% of reports.

 Proportions by seriousness and sex were comparable to primary series

• Most reports (90%) were non-serious

• Most reports (65%) were among females

Doses

admin†

Total

reports

Median 

age

Male‡

n (%)

Female‡

n (%)

Non-serious

n (%)

Serious

n (%)

93,118,318 52,063 53 years 17,281 (33) 33,692 (65) 47,014 (90) 5,049 (10)
U.S. reports to VAERS following 1st

booster mRNA COVID-19 vaccination, 

by race and ethnicity* (as of April 11, 2021) 

Race and ethnicity n (%)

Non-Hispanic White 25,508 (49)

Unknown or not reported 14,787 (28)

Hispanic† 3,616 (7)

Non-Hispanic Other 2,987 (6)

Non-Hispanic Black 2,264 (4)

Non-Hispanic Asian 1,764 (3)

Non-Hispanic multiracial 561 (1)

Non-Hispanic American

Indian/Alaskan Native 520 (<1)

Non-Hispanic Native Hawaiian

or Other Pacific Islander 56 (<1)

Total 52,063

* Among persons receiving Pfizer-BioNTech dose 3: children and adolescents ages 12–15 years 

vaccinated during Jan 3 – April 11, 2022, and ages 16–17 years vaccinated during Dec 9, 2021 –

April 11, 2022; adults ages ≥18 years vaccinated during September 22, 2021 – April 11, 2022. 

Among persons receiving Moderna booster doses, adults ages ≥18 years vaccinated during October 

20, 2021 – April 11, 2022. All reports received and processed as of April 11, 2022. 

† Includes persons reported as of Hispanic ethnicity, but of unreported or unknown race.

25
Most frequently reported non-serious adverse events to VAERS following 1st booster 

mRNA COVID-19 vaccination (47,014 total non-serious reports)* (as of April 11, 2022)

26

Rank Adverse event (not mutually exclusive) n (%)

1 Headache 6,119 (13)

2 Pyrexia 5,840 (12)

3 Pain 5,783 (12)

4 Fatigue 5,420 (12)

5 Expired Product Administered 5,082 (11)

6 Chills 4,836 (10)

7 Product Storage Error 4,030 (9)

8 Pain In Extremity 3,813 (8)

9 Nausea 3,209 (7)

10 Dizziness 2,982 (6)

Non-serious reports (all reports) Non-serious reports (clinical outcomes)†

Rank Adverse event (not mutually exclusive) n (%)

1 Headache 6,119 (13)

2 Pyrexia 5,840 (12)

3 Pain 5,783 (12)

4 Fatigue 5,420 (12)

5 Chills 4,836 (10)

6 Pain In Extremity 3,813 (8)

7 Nausea 3,209 (7)

8 Dizziness 2,982 (6)

9 Urticaria 2,966 (6)

10 Lymphadenopathy 2,896 (6)

* Among persons receiving Pfizer-BioNTech dose 3: children and adolescents ages 12–15 years vaccinated during Jan 3 – April 11, 2022, and ages 16–17 years vaccinated during Dec 9, 

2021 – April 11, 2022; adults ages ≥18 years vaccinated during September 22, 2021 – April 11, 2022. Among persons receiving Moderna booster doses, adults ages ≥18 years vaccinated 

during October 20, 2021 – April 11, 2022. All reports received and processed as of April 11, 2022. 

† Determined by subject matter expert consensus
Most frequently reported serious adverse events to VAERS following 1st booster 

mRNA COVID-19 vaccination (5,049 total serious reports) (as of April 11, 2022)

27

Rank Adverse event (not mutually exclusive) n (%)

1 Covid-19 1,196 (24)

2 Sars-Cov-2 Test Positive 997 (20)

3 Dyspnoea 817 (16)

4 Death 549 (11)

5 Chest Pain 440 (9)

6 Pyrexia 436 (9)

7 Asthenia 435 (9)

8 Condition Aggravated 396 (8)

9 Fatigue 386 (8)

10 Pain 369 (7)

Serious reports (all reports) Serious reports (clinical outcomes)†

Rank Adverse event (not mutually exclusive) n (%)

1 Covid-19 1,196 (24)

2 Sars-Cov-2 Test Positive 997 (20)

3 Dyspnoea 817 (16)

4 Death 549 (11)

5 Chest Pain 440 (9)

6 Pyrexia 436 (9)

7 Asthenia 435 (9)

8 Fatigue 386 (8)

9 Pain 369 (7)

10 Cough 328 (7)

* Among persons receiving Pfizer-BioNTech dose 3: children and adolescents ages 12–15 years vaccinated during Jan 3 – April 11, 2022, and ages 16–17 years vaccinated during Dec 9, 

2021 – April 11, 2022; adults ages ≥18 years vaccinated during September 22, 2021 – April 11, 2022. Among persons receiving Moderna booster doses, adults ages ≥18 years vaccinated 

during October 20, 2021 – April 11, 2022. All reports received and processed as of April 11, 2022. 

† Determined by subject matter expert consensus
28

 Median age in myocarditis case reports is younger vs. pericarditis

 Male predominance observed for myocarditis case reports but not for pericarditis

Myocarditis (n=110) Pericarditis (n=38)

Median age (IQR†) 23 (16–36) 46 (25–62)

Median time to symptom onset (IQR†) 3 (2–4) 3 (1–7)

Male, n (%) / Female, n (%) 89 (81%) / 21 (19%) 18 (47%) / 20 (53%)

U.S. reports to VAERS of myocarditis and pericarditis following 1st booster 

mRNA COVID-19 vaccination, by age, time to symptom onset, and sex* 

(as of April 11, 2022) 

* Among persons receiving Pfizer-BioNTech dose 3: children and adolescents ages 12–15 years vaccinated during Jan 3 – April 11, 2022, and ages 16–17 years vaccinated during Dec 9, 

2021 – April 11, 2022; adults ages ≥18 years vaccinated during September 22, 2021 – April 11, 2022. Among persons receiving Moderna booster doses, adults ages ≥18 years vaccinated 

during October 20, 2021 – April 11, 2022. All reports received and processed as of April 11, 2022. 

† Interquartile range.
29

 Most myocarditis 

reports among ages 

12–29 years

 Pericarditis reports 

distributed fairly 

evenly among age 

groups*

0

2

4

6

8

10

12

14

16

18

12 to 15 16 to 17 18 to 24 25 to 29 30 to 39 40 to 49 50 to 64 65+

Verified reports to VAERS

Age group, years

Myocarditis or pericarditis following 1st mRNA COVID-19 booster 

vaccination among males, days 0–7, by age group, VAERS

Pfizer, myocarditis Moderna, myocarditis Pfizer, pericarditis Moderna, pericarditis

* Complicates estimation of reporting rates
0

2

4

6

8

10

12

14

16

18

12 to 15 16 to 17 18 to 24 25 to 29 30 to 39 40 to 49 50 to 64 65+

Verified reports to VAERS

Age group, years

Myocarditis or pericarditis following 1st mRNA COVID-19 booster 

vaccination among males, days 0–7, by age group, VAERS

Pfizer, myocarditis Moderna, myocarditis Pfizer, pericarditis Moderna, pericarditis

30

 Most myocarditis 

reports among ages 

12–29 years

 Pericarditis reports 

distributed fairly 

evenly among age 

groups*

* Complicates estimation of reporting rates
31

 Most myocarditis 

reports among ages 

12–29 years

 Pericarditis reports 

distributed fairly 

evenly among age 

groups*

* Complicates estimation of reporting rates

0

2

4

6

8

10

12

14

16

18

12 to 15 16 to 17 18 to 24 25 to 29 30 to 39 40 to 49 50 to 64 65+

Verified reports to VAERS

Age group, years

Myocarditis or pericarditis following 1st mRNA COVID-19 booster 

vaccination among males, days 0–7, by age group, VAERS

Pfizer, myocarditis Moderna, myocarditis Pfizer, pericarditis Moderna, pericarditis
32

 Few reports among 

females of either 

condition

 Both myocarditis 

and pericarditis 

reports distributed 

fairly evenly among 

age groups

0

2

4

6

8

10

12

14

16

18

12 to 15 16 to 17 18 to 24 25 to 29 30 to 39 40 to 49 50 to 64 65+

Verified reports to VAERS

Age group, years

Myocarditis or pericarditis following 1st mRNA COVID-19 booster 

vaccination among females, days 0–7, by age group, VAERS

Pfizer, myocarditis Moderna, myocarditis Pfizer, pericarditis Moderna, pericarditis
Reporting rates of myocarditis (per 1 million doses administered) among 

males following 1st mRNA COVID-19 booster vaccination, by risk interval*

 41,670,922 1st mRNA COVID19 booster vaccinations 

administered in males*

 Reporting rates exceed 

background incidence in 

ages 12–29 years

 Reporting rates highest in 

males ages 16–17 years, 

followed by 12–15 years

* Among persons receiving Pfizer-BioNTech dose 3: children and adolescents ages 12–15 years vaccinated during Jan 3 – April 11, 2022, and ages 16–17 years vaccinated during Dec 9, 

2021 – April 11, 2022; adults ages ≥18 years vaccinated during September 22, 2021 – April 11, 2022. Among persons receiving Moderna booster doses, adults ages ≥18 years 

vaccinated during October 20, 2021 – April 11, 2022. All reports received and processed as of April 11, 2022. Doses administered as of April 14, 2022. An estimated 1–10 cases of 

myocarditis per 100,000 person years occurs among people in the United States, regardless of vaccination status; adjusted for day 0–7 and 0–21 risk periods, this estimated 

background is 0.2 to 2.2 per 1 million person risk period. 33

Pfizer-BioNTech Moderna

age group Days 0–7 Days 0–7

12 to 15 17.2 N/A

16 to 17 23.2 N/A

18 to 24 5.4 12.1

25 to 29 4.8 4.0

30 to 39 1.5 1.5

40 to 49 0.0 <1.0

50 to 64 <1.0 0.0

65+ <1.0 <1.0
Clinical outcomes of myocarditis and pericarditis following 1st mRNA 

COVID-19 booster vaccination*

 93,118,318 total 

booster doses 

administered*

 Patients not 

hospitalized 

received outpatient 

care

 Patients still 

recovering are 

stable or improving

34

* Doses of Pfizer-BioNTech dose 3 administered among children and adolescents ages 12–15 years during January 6 – Apr 14, 2022; adolescents ages 16–17 years during Dec 9, 

2021 – April 14, 2022; adults ages ≥18 years during September 22, 2021 – April 14, 2022. Doses of Moderna dose 3 administered among adults ages ≥18 years during October 28, 

2021 – April 14, 2022 

Myocarditis 

(N=110)

Pericarditis 

(N=38)

Hospitalized 90/110 (82%) 15/38 (39%)

Discharged 90/90 (100%) 15/15 (100%)

Known outcomes 86/90 (96%) 14/15 (93%)

Recovered from symptoms at 

last follow up 51/86 (59%) 10/14 (71%)
35

Smartphone-based active safety monitoring

http://cdc.gov/vsafe

Enroll yourself or 

your dependent 

after any dose!
Active safety monitoring for COVID-19 vaccines

v-safe is a CDC smart phone-based monitoring program for COVID-19 

vaccine safety in the U.S.

• Uses text messaging and web surveys to check in with vaccine recipients after 

vaccination

• Can register at any time: after first, second, or third dose

• Solicits participants' reports on how they feel after COVID-19 vaccination

‒ Local injection site reactions (i.e., pain, redness, swelling)

‒ Systemic reactions (i.e., fatigue, headache, joint pain)

‒ Health impacts (unable to perform normal daily activities, missed school 

or work, or received care) 

36
Patterns of vaccination for 729,720 v-safe participants aged 

≥18 years who reported a booster dose

Moderna (%) Pfizer-BioNTech (%) Janssen (%) Total

Moderna 311,374 (94) 17,034 23,211 351,619

Pfizer-BioNTech 19,538 336,618 (95) 13,685 369,841

Janssen 247 238 7,775 (17) 8,260

Total 331,159 353,890 44,671 729,720

Primary series

Booster

dose

Data as of April 10, 2022. Includes participants who completed at least one survey in the first week after each dose (administered beginning 

September 22, 2021 for Pfizer-BioNTech and October 20,2021 for Moderna and Janssen). 37
Demographic summary of 729,720 v-safe participants aged 

≥18 years who reported a booster dose

Data as of April 10, 2022. Includes participants who completed at least one survey in the first week after each dose (administered beginning 

September 22, 2021 for Pfizer-BioNTech and October 20,2021 for Moderna and Janssen). 

Abbreviations: AI/AN = American Indian/Alaska Native; NHPI = Native Hawaiian or other Pacific Islander; AA=African American.

Characteristic % of participants

Sex

Female 62.8

Male 36.4

Unknown 0.8

Age group (years)

18–49 268,632

50–64 189,735

65–74 210,566

75–84 56,051

≥85 4,736

Characteristic % of participants

Ethnicity

Hispanic or Latino 6.7

Not Hispanic/ Latino 90.2

Unknown 3.1

Race

AI/AN 0.4

Asian 5.4

Black or AA 5.6

NHPI 0.2

White 82.9

Multiracial 1.8

Other 1.9

Unknown 1.8

38
Reactions and health impact events reported by v-safe participants aged ≥18 years at 

least once in days 0–7 after homologous Pfizer-BioNTech vaccination, by dose

Includes 336,618 participants who completed at least one survey in the first week after each dose, data collected during September 22–April 10, 2022 

* Dose 2 compared to dose 3: statistically significant difference (p-value <0.05) using multivariable generalized estimating equations model that accounted for 

the correlation between registrants and adjusted for demographic variables. 39

0

10

20

30

40

50

60

70

80

90

100

Any injection site

reaction

Any systemic reaction Any health impact Unable to perform

daily activities

Unable to work Needed medical care

Percentage

Dose 1 Dose 2 Booster

* *

*

*

*

*
Reactions and health impact events reported by v-safe participants aged 12–17 years 

at least once in days 0–7 after homologous Pfizer-BioNTech vaccination, by dose

Includes 3,694 participants who completed at least one survey in the first week after each dose, data collected during December 9, 2021–April 10, 2022 

* Dose 2 compared to dose 3: statistically significant difference (p-value <0.05) using multivariable generalized estimating equations model that accounted for 

the correlation between registrants and adjusted for demographic variables. 40

0

10

20

30

40

50

60

70

80

90

100

Any injection site

reaction

Any systemic reaction Any health impact Unable to perform

daily activities

Unable to work or

attend school

Needed medical care

Percentage

Dose 1 Dose 2 Booster

*

*

*

*

*
Reactions and health impact events reported by v-safe participants aged ≥18 years at 

least once in days 0–7 after homologous Moderna vaccination, by dose

Includes 311,374 participants who completed at least one survey in the first week after each dose, data collected during October 20–April 10, 2022 

* Dose 2 compared to dose 3: statistically significant difference (p-value <0.05) using multivariable generalized estimating equations model that accounted for 

the correlation between registrants and adjusted for demographic variables. 41

0

10

20

30

40

50

60

70

80

90

100

Any injection site

reaction

Any systemic reaction Any health impact Unable to perform

daily activities

Unable to work Needed medical care

Percentage

Dose 1 Dose 2 Booster

* *

*

*

*
Summary of the safety of 1st booster 

mRNA COVID-19 vaccination

42
Summary

VSD Rapid Cycle Analysis (RCA) monitoring 

 The only safety signal detected for any pre-specified outcome following 1st booster dose has 

been for myocarditis/pericarditis in the 21 days after mRNA COVID-19 vaccination

 Myocarditis/pericarditis differed between persons ages 12–39 and 40+ years 

• 12–39 years: mostly myocarditis and myopericarditis with onset <7 days after vaccination

• 40+ years: mostly pericarditis; cases more spread out in the 3 weeks after vaccination

 For persons ages 12–39 years, rate ratios for myocarditis/pericarditis 0–7 days after 1st

booster dose were elevated

• Rate per million 1st booster doses administered was not higher than after dose 2 mRNA 

COVID-19 vaccination 

 For persons ages 40 years and older, rate ratios for myocarditis/pericarditis were elevated, 

but less so in the 0–7 and 0–21 days after the 1st booster dose compared to persons ages 12–

39 years

43
Summary (cont.)

VAERS monitoring (after 93 million 1st mRNA COVID-19 booster vaccinations in the United Sates)

 Local and systemic reactions are most commonly reported following 1st booster dose

 110 verified reports of myocarditis and 38 of pericarditis

• Myocarditis reporting rates were highest among young males (ages 12–29 years)

‒ Reporting rates for persons ages 12–29 years following 1st booster exceeded 

background, but were lower compared to post-dose 2 rates with primary series

• Pericarditis reports were relatively rare, and distributed evenly among males and 

females and among the varied age groups

• More myocarditis (82%) than pericarditis (39%) case patients were hospitalized 

‒ Most hospitalized patients recovered from symptoms at time of follow up*

V-safe monitoring 

 No unusual or unexpected findings or new safety concerns identified

*Follow up varies based on timing of the report and healthcare records availability 44
Summary (cont.)

45

 Active surveillance in VSD and passive surveillance in VAERS suggests an increased risk of 

myocarditis/pericarditis following the 1st mRNA COVID-19 booster vaccination

• For myocarditis, the findings are consistent with those observed with primary series 

vaccination, but the risk appears to be lower following the 1st booster dose compared 

to dose 2 of primary series

‒ Risk of myocarditis is highest in younger males with onset clustering within 0–7 

days of 1st booster vaccination

‒ Pericarditis is less common, more evenly distributed between males and females, 

and more evenly distributed across age groups

 Local and systemic reactogenicity and health impacts appear similar or attenuated for 1st

mRNA COVID-19 booster vaccination compared to dose 2 of primary series

 Monitoring is ongoing 
Acknowledgments

 VAERS team

 CISA team

 VSD team

 COVID-19 Vaccine Task Force Data Monitoring 

and Reporting Group

 CDC Immunization Safety Office

 FDA/Center for Biologics Evaluation and Research

 State and local health departments 

 Healthcare providers and other stakeholders 

reporting to VAERS

 V-safe team

 V-safe participants

 Anne Hause

 James Baggs

 Paige Marquez

 Isaac McCullum

 Bicheng Zhang

 Tanya Myers

46

 Kaiser Permanente Northern California

• Nicky Klein, Laurie Aukes, Berwick Chan, Bruce Fireman, 

Kristin Goddard, Ned Lewis, Karen Nunley, Pat Ross, Arnold 

Yee, Ousseny Zerbo, Nandini Bahkshi

 Marshfield Clinic Research Institute

• Jim Donahue, Ed Belongia, Tom Boyce, Kayla Hanson, 

Burney Kieke, Dave McClure, Erica Scotty

 CDC Immunization Safety Office

• Eric Weintraub, Tat’Yana Kenigsberg, Mike McNeil, 

Jonathan Duffy, Frank Destefano, Tanya Myers, Tom 

Shimabukuro, Matt Oster

 VSD Sites

• HealthPartners Institute, Minneapolis, Minnesota

• Kaiser Permanente Colorado, Denver, Colorado

• Kaiser Permanente Northwest, Portland, Oregon

• Kaiser Permanente Southern California, Los Angeles, 

California

• Kaiser Permanente Washington, Seattle, Washington

• Denver Health, Denver, Colorado
For more information, contact CDC

1-800-CDC-INFO (232-4636)

TTY: 1-888-232-6348 www.cdc.gov

The findings and conclusions in this report are those of the authors and do not necessarily represent the 

official position of the Centers for Disease Control and Prevention.

Thank you!