cdc.gov/coronavirus

Update on myocarditis following mRNA 

COVID-19 vaccination

Advisory Committee on Immunization Practices 

(ACIP)

June 23, 2022

Tom Shimabukuro, MD, MPH, MBA

CDC COVID-19 Vaccine Coordination Unit
Topics

 Background on classic myocarditis and myocarditis associated with 

mRNA COVID-19 vaccination

 Update on myocarditis following mRNA COVID-19 vaccination with 

a focus on children ages 5–17 years*

• Findings from the Vaccine Adverse Event Reporting System (VAERS)

• Findings from the Vaccine Safety Datalink (VSD)

 Comparative risk for myocarditis between the two mRNA COVID-19 

vaccines, Moderna and Pfizer-BioNTech

2

* Analyses focus on children ages 5–11 years for the 2-dose (10 μg) primary series separated by at least 3 weeks, and children ages 12–17 years for the 2-dose (30 μg) 

primary series separated by at least 3 weeks followed by a booster dose at least 5 months after completion of the primary series; data outside of these authorizations 

and recommendations (e.g., off authorization use, vaccination errors, special population authorizations/recommendations) are not included in these analyses 
Epidemiology of classic myocarditis in children (excluding infants) 

 Usually an infectious cause, typically viral or presumed to be viral, although infection with a pathogen is 

frequently not identified (only ~40% of time a pathogen is identified)1,2,3

 Can be due to direct microbial infection of myocardial cells and/or ongoing inflammatory response, with 

or without clearance of pathogen4,5,6

• Can also be toxin-mediated or in setting of systemic infection or infection of non-cardiac tissue

 Rarer causes include autoimmune, hypersensitivity, and giant cell myocarditis

 Incidence in males > females starting after age 5 years7

 Previously unrecognized myocarditis was identified as cause of death in 8% of cases of sudden, 

unexplained death in 1–17- year-olds8 and 9% of sudden death in athletes9

 It is common to not identify a pathogen or possible infectious etiology for myocarditis

• Based on case series, where autopsy tissues were examined and tissue-based infectious disease testing was 

performed, a specific infectious cause was only identified in 13%–36% of cases across age groups6,10,11

• For a case series where endomyocardial biopsy tissues were tested, viral nucleic acids were detected in heart 

tissues in ~38% (adults and children combined)1

3

1Bowles et al. J Am Coll Cardiol. 2003;42:466-72. 2Simpson et al. J Am Coll Cardiol. 2013;61:(10_Supplement) E1264. 3Park et al. J Korean Med Sci. 2021;36:e232. 4Caforio et al. Eur 

Heart J. 2013;34:2636-48, 2648a-2648d. 5Feldman et al. N Engl J Med. 2000;343:1388-98. 6Guarner et al. Hum Pathol. 2007;38:1412-9. 7Arola et al. J Am Heart Assoc. 2017;6:e005306. 

8Burns et al. J Pediatr X. 2020;2:100023. 9Maron et al. Circulation. 2009;119:1085-92. 10Weber et al. Arch Dis Child. 2008;93:594-8. 11Ilina et al. Pediatrics. 2011;128:e513-20. 
4

Previously presented at the June 23, 2021, ACIP meeting: https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2021-06/02-COVID-Oster-508.pdf

LOS = Length of hospital stay 
5

* https://www.cdc.gov/vaccines/acip/meetings/index.html, https://www.cdc.gov/vaccinesafety/research/publications/index.html † Oster et al. JAMA. 2022;327:331-340.

‡ Law et al. Circulation. 2021;144:e123-e135. Ghelani et al. Circ Cardiovasc Qual Outcomes. 2012;5:622-7. Kim et al. Korean Circ J. 2020;50:1013-1022. Messroghli et al. Am Heart J. 2017;187:133-

144. Patel et al. J Am Heart Assoc. 2022;11:e024393.

¶ There are rare reports in the literature, especially from other countries, but it is unclear to what extent such cases were investigated

Characteristic

Myocarditis associated with mRNA 

COVID-19 vaccination*,† Viral myocarditis‡

Inciting exposure mRNA COVID-19 vaccination

• Dose 2 > Dose 1

Viral illness

• 30–60% with asymptomatic viral 

course

Demographics Most cases in adolescents and young 

adults, males > females

Males > females, male incidence peaks 

in adolescence and gradually declines

Symptom onset A few days after vaccination, most within 

a week 1–4 weeks after viral illness

Fulminant course Rare¶ 23%

ICU level support ~2% ~50%

Mortality/transplant Rare¶ 11–22%

Cardiac dysfunction 12% 60%

Recovery of cardiac function Nearly all ~75%

Time to recovery of cardiac 

function (ejection fraction on 

cardiac echo), if initially poor

Hours to days Days to weeks to months
+

Vaccine Adverse Event 

Reporting System

http://vaers.hhs.gov

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

6
VAERS

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

VAERS accepts reports from everyone (healthcare professionals, patients, 

parents, caregivers, manufacturers, etc.) regardless of the plausibility of 

the vaccine causing the event or the clinical seriousness of the event

7
Reports to VAERS of myocarditis after Pfizer-BioNTech vaccination 

among children ages 5–17 years (as of May 26, 2022)

*

8

Preliminary reports of 

myocarditis (N=972)

Under review†

(n=214)

Met CDC definition‡

(n=635)

* As of May 26, 2022, primary series vaccination among children ages 16–17 years since Dec 14, 2020; 

children ages 12–15 years since May 10, 2021; children ages 5–11 years since Nov 3, 2021; 1st dose booster 

vaccination among children ages 16–17 years since Dec 9, 2021; children ages 12–15 years since Jan 5, 2022. 

† Awaiting medical records and/or healthcare provider interview; some still processing

‡ Adjudicated after healthcare provider interview and/or medical record review; CDC myocarditis case 

definition available at: https://www.cdc.gov/mmwr/volumes/70/wr/mm7027e2.htm

 54.8 million total Pfizer-BioNTech doses 

administered to children ages 5–17 years 

in the Unites States

• 27.7 million dose 1

• 23.3 million dose 2

• 3.8 million 1st booster dose (ages 12–17 years) Misclassified, not a 

primary series or 1st dose 

booster, or did not meet 

definition ‡ (n=123)
Verified* U.S. reports to VAERS of myocarditis after Pfizer-BioNTech vaccination 

among children ages 5–17 years, by time to symptom onset† and dose number 

(N=630, as of May 26, 2022)

9 *Verified according to CDC myocarditis case definition available at: https://www.cdc.gov/mmwr/volumes/70/wr/mm7027e2.htm

† 630 of 635 (99%) with known 

time to symptom onset; 49 (8%) 

reports with time to symptom 

0 onset >10 days

50

100

150

200

250

0 1 2 3 4 5 6 7 8 9 10

Verified reports of myocarditis

Time to symptom onset, days

Dose 1 Dose 2 1st Booster Dose
VAERS reporting rates of myocarditis (per 1 million doses administered) after mRNA 

COVID-19 vaccination, days 0–7 and 8–21 post-vaccination*,†

* As of May 26, 2022; reports verified to meet case definition by provider interview or medical record review; primary series and 1st booster doses only

† 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 days 0–7 

and 8–21 risk intervals, this estimated background is 0.2 to 2.2 per 1 million person-day 0–7 risk interval and 0.4 to 3.8 per 1 million person-day 8–21 risk interval

(peach shaded cells indicate that reporting rate exceeded estimated background incidence for the period)

10

0–7 days 8–21 days 0–7 days 8–21 days

Males Males Females Females

Age (yrs) Dose 1 Dose 2 Booster Dose 1 Dose 2 Booster Dose 1 Dose 2 Booster Dose 1 Dose 2 Booster

5–11 0.2 2.6 0.0 0.6 0.0 0.0 0.2 0.7 0.0 0.2 0.0 0.0

12–15 5.3 46.4 15.3 1.2 1.2 0.9 0.7 4.1 0.0 0.4 0.2 0.9

16–17 7.2 75.9 24.1 1.7 3.2 1.3 0.0 7.5 0.0 0.7 0.4 0.0

18–24 4.2 38.9 9.9 1.1 2.2 0.4 0.6 4.0 0.6 0.2 0.7 0.0

25–29 1.8 15.2 4.8 0.4 1.1 0.5 0.4 3.5 2.0 0.2 0.0 0.8

30–39 1.9 7.5 1.8 0.4 0.8 0.2 0.6 0.9 0.6 0.3 0.2 0.0

40–49 0.5 3.3 0.4 0.2 0.5 0.0 0.4 1.6 0.6 0.2 0.2 0.0

50–64 0.5 0.7 0.4 0.2 0.3 0.1 0.6 0.5 0.1 0.2 0.5 0.1

65+ 0.2 0.3 0.6 0.3 0.2 0.1 0.1 0.5 0.1 0.1 0.2 0.1

PfizerBioNTech

PfizerBioNTech 

and 

Moderna
CDC enhanced surveillance for myocarditis outcomes following mRNA COVID-19 

vaccination in VAERS case reports among children ages 5–17 years*

11

 Purpose: Assess functional status and clinical outcomes among individuals 

reported to have developed myocarditis after COVID-19 mRNA vaccination

 Methods: A two-component survey conducted at least 90 days after the 

onset of myocarditis symptoms

• Patient or parent survey: Focused on ascertaining functional status, clinical 

symptoms, quality of life, and need for medication or other medical treatment 

• Healthcare provider (e.g., cardiologist) survey: Gather data on cardiac health and 

functional status

* https://www.cdc.gov/coronavirus/2019-ncov/vaccines/safety/myo-outcomes.html; surveillance project 

includes two separate cohorts, children ages 5–11 years and people ages 12–29 years 
12

CDC enhanced surveillance for myocarditis outcomes following mRNA COVID-19 

vaccination in VAERS case reports among children ages 5–17 years

 During the surveillance periods (through November 2021 for 12–17 years and 

April 2022 for 5–11 years), VAERS received 430 reports of myocarditis or 

myopericarditis after mRNA COVID-19 vaccination in children ages 5–17 years 

that met CDC case definition* and were at least 90 days post-myocarditis 

diagnosis 

• 190 completed the patient or parent survey, 128 were unreachable on multiple attempts, 98 

had no telephone contact information in the report, and 7 declined to participate 

• 226 cardiologists or other healthcare providers (HCP) completed a survey, 120 were 

unreachable on multiple attempts, and 65 had no telephone contact information in the report

* https://www.cdc.gov/mmwr/volumes/70/wr/mm7027e2.htm
CDC enhanced surveillance for myocarditis outcomes following mRNA COVID-19 

vaccination in VAERS case reports among children ages 5–17 years

13

0

20

40

60

80

100

120

140

Same cardiac status as at the

initial myocarditis diagnosis

Improved, but not fully

recovered

Probably fully recovered,

awaiting additional

information

Fully recovered

Number of Patients

Patient recovery

63% 

18% 17% 

0% 

Note: 5 (2%) providers were unsure

 Based on the cardiologists or healthcare provider assessment, most patients appear to have 

fully or probably fully recovered from their myocarditis 

• 226 patients received a follow-up assessment by a cardiologist or other healthcare 

provider regarding their myocarditis recovery

Children ages 5–17 years

80.1% fully or 

probably fully 

recovered 
CDC enhanced surveillance for myocarditis outcomes following mRNA COVID-19 

vaccination in VAERS case reports among children ages 5–17 years

14

Key findings

 At least 90 days after myocarditis diagnosis, most patients who were reached reported no 

impact on their quality of life, and most did not report missing school or work

 Most (80.1%) healthcare providers who completed surveys indicated the patient was fully 

recovered or probably fully recovered

• There was substantial heterogeneity in initial and follow-up treatment and testing

• There did not appear to be a single test that was indicative of recovery

Next steps

 Additional follow-up with patients who were not yet recovered at time of the 90+ day 

survey (and their healthcare providers) to further assess recovery status at 12+ months
Vaccine Safety Datalink (VSD)

15

 Established in 1990

 Collaborative project between CDC and 9 integrated healthcare organizations 
VSD Rapid Cycle Analysis (RCA)

Aims:

 To monitor the safety of COVID-19 vaccines weekly using 

prespecified outcomes of interest among VSD members

 To describe the uptake of COVID-19 vaccines over time among 

eligible VSD members overall and in strata by age, site, and 

race/ethnicity

16
VSD COVID-19 vaccine RCA prespecified surveillance outcomes

17

Prespecified outcomes Settings

Acute disseminated encephalomyelitis Emergency dept, Inpatient

Acute myocardial infarction – First ever in EHR in ICD-10 era Emergency dept, Inpatient

Acute respiratory distress syndrome (descriptive monitoring only) Emergency dept, Inpatient

Anaphylaxis – First in 7 days in EHR in ICD-10 era (descriptive monitoring only) Emergency dept, Inpatient

Appendicitis Emergency dept, Inpatient

Bell’s palsy – First ever in EHR in ICD-10 era Emergency dept, Inpatient, Outpatient

Cerebral venous sinus thrombosis Emergency dept, Inpatient

Disseminated intravascular coagulation Emergency dept, Inpatient

Encephalitis / myelitis / encephalomyelitis Emergency dept, Inpatient

Guillain-Barré syndrome Emergency dept, Inpatient

Immune thrombocytopenia Emergency dept, Inpatient, Outpatient

Kawasaki disease (descriptive monitoring only) Emergency dept, Inpatient

Multisystem inflammatory syndrome in children/adults (MIS-C/MIS-A) (descriptive monitoring only) Emergency dept, Inpatient

Myocarditis / pericarditis – First in 60 days in EHR in ICD-10 era Emergency dept, Inpatient

Narcolepsy / cataplexy (descriptive monitoring only) Emergency dept, Inpatient, Outpatient

Pulmonary embolism – First ever in EHR in ICD-10 era Emergency dept, Inpatient

Seizures Emergency dept, Inpatient

Stroke, hemorrhagic Emergency dept, Inpatient

Stroke, ischemic Emergency dept, Inpatient

Thrombosis with thrombocytopenia syndrome – First ever in EHR in ICD-10 era Emergency dept, Inpatient

Thrombotic thrombocytopenic purpura Emergency dept, Inpatient

Transverse myelitis Emergency dept, Inpatient

Venous thromboembolism – First ever in EHR in ICD-10 era Emergency dept, Inpatient, Outpatient

EHR = Electronic 

health record
VSD Rapid Cycle Analysis (RCA) analytic strategy

 For the primary analysis, the number of outcomes observed in the risk interval 

after COVID-19 vaccination were compared to the number expected

 The expected was derived from “vaccinated concurrent comparators” who 

were in a comparison interval after COVID-19 vaccination

 On each day that an outcome occurred, vaccinees who were in their risk 

interval were compared with similar vaccinees who were concurrently in their 

comparison interval

• Comparisons were adjusted for age group, sex, race/ethnicity, VSD site, as 

well as calendar date

 For the prespecified outcome myocarditis/pericarditis, cases were verified 

using the CDC case definition (https://www.cdc.gov/mmwr/volumes/70/wr/mm7027e2.htm) 

18
19

Pfizer-BioNTech vaccine doses administered* in VSD in pediatric age groups

5–11 years to date:

417,439 dose 1

389,855 dose 2

12–15 years to date:

419,116 dose 1

405,071 dose 2

16–17 years to date: 

213,076 dose 1

206,959 dose 2

* Pfizer-BioNTech was the only authorized vaccine in these ages during the surveillance period 

Over 2 million total PfizerBioNTech primary series 

doses administered in 

children ages 5–17 years 
Pfizer-BioNTech vaccine booster doses administered* in VSD in pediatric age groups

* Pfizer-BioNTech was the only authorized vaccine in these ages during the surveillance period 

5–11 years to date:

20,255 booster doses

12–15 years to date:

137,353 booster doses

16–17 years to date: 

92,167 booster doses

20
VSD RCA findings for myocarditis and pericarditis following mRNA 

COVID-19 vaccines

 Children ages 5–11 years (primary series only)

• No statistical signals to date for myocarditis/pericarditis

 People ages ≥12 years, including adults

• Statistical signals detected for myocarditis/pericarditis for Pfizer-BioNTech and for both 

mRNA COVID-19 vaccines combined for primary series vaccination

• Statistical signals detected for myocarditis/pericarditis for both mRNA COVID-19 vaccines 

combined for 1st booster dose
Day of symptom onset of verified myocarditis/pericarditis among children ages 5–17 

years after either primary series dose of an mRNA COVID-19 vaccine

22

Two overlapping clusters identified

Days 0-3 (P<0.001)

Days 0-4 (P<0.001)

Based on data through 

May 28, 2022
Verified myocarditis and pericarditis in the 0–7-day risk interval among MALE

children ages 5-17 years by age group and dose (compared with outcome events in vaccinated 

comparators on the same calendar days, based on data through May 28, 2022) 

23

NE=not estimable

* Comparison interval is 22–42 days after either dose. † Adjusted for VSD site, 5-year age group, sex, race/ethnicity, and calendar date. 1st booster analyses are also adjusted for time since primary series.

‡ One case was non-informative for the risk interval analyses but was included in the excess risk calculation estimates. 

¶ Subgroup events may not sum to “12–17” total due to non-informative events. 

Age Group Pfizer-BioNTech

dose

Events in

Risk Interval

Events in 

Comparison Interval*

Adjusted

Rate Ratio† 

95%

Conf Interval

2-sided

P-value

Excess cases in Risk

Period per million doses

5–11 Years

Dose 1 0 0 NE NE NE NE

Dose 2‡ 2 0 NE 0.87 – ∞ 0.061 15.2

1st Booster 0 0 NE NE NE NE

12–17 Years¶

Dose 1 3 1 14.00 1.20 – 421.96 0.035 8.9

Dose 2 44 1 160.52 30.19 – 3343.73 <0.001 147.0

1st Booster 9 1 14.98 1.39 – 484.33 0.023 85.1

12–15 Years

subgroup

Dose 1 2 1 13.63 0.94 – 433.36 0.056 8.8

Dose 2 28 1 104.88 18.45 – 2267.59 <0.001 151.0

1st Booster 1 1 3.97 0.05 – 320.79 0.560 12.7

16–17 Years

subgroup

Dose 1 1 0 NE 0.13 – ∞ 0.285 9.6

Dose 2 14 0 NE 10.20 – ∞ <0.001 138.7

1st Booster 7 0 NE 1.16 – ∞ 0.038 200.3
Verified myocarditis and pericarditis in the 0–7-day risk interval among FEMALE

children ages 5-17 years by age group and dose (compared with outcome events in vaccinated 

comparators on the same calendar days, based on data through May 28, 2022) 

24

Age Group Pfizer-BioNTech

dose

Events in

Risk Interval

Events in 

Comparison Interval*

Adjusted

Rate Ratio† 

95%

Conf Interval

2-sided

P-value

Excess cases in Risk

Period per million doses

5-11 Years

Dose 1 0 0 NE NE NE NE

Dose 2 0 0 NE NE NE NE

1st Booster 0 0 NE NE NE NE

12 – 17 Years‡

Dose 1 1 1 9.16 0.23 – 364.80 0.200 2.8

Dose 2 5 1 18.15 1.62 – 558.73 0.018 18.4

1st Booster 2 3 0.79 0.07 – 7.49 0.835 - 5.0

12 – 15 Years

subgroup

Dose 1 0 0 NE NE NE 0.0

Dose 2 4 0 NE 1.01 – ∞ 0.049 24.8

1st Booster 0 0 NE NE NE 0.0

16 – 17 Years

subgroup

Dose 1 1 1 12.11 0.31 – 477.83 0.154 8.4

Dose 2 1 1 6.10 0.16 – 239.90 0.283 7.9

1st Booster 2 3 1.10 0.11 – 9.58 0.924 4.0

NE=not estimable

* Comparison interval is 22–42 days after either dose. † Adjusted for VSD site, 5-year age group, sex, race/ethnicity, and calendar date. 1st booster analyses are also adjusted for time since primary series.

‡ Subgroup events may not sum to “12–17” total due to non-informative events. 
VSD incidence rates of verified myocarditis/pericarditis in the 0–7 days following PfizerBioNTech vaccination, December 14, 2020–May 28, 2022

25

Children ages 5-17 years Cases Doses Incidence rate per

million doses admin.

95% Confidence

Intervals

5–11 years

Males – Dose 1 0 211,644 0.0 0.0 – 14.2

Males – Dose 2 3 197,465 15.2 3.1 – 44.5

Females – Dose 1 0 205,795 0.0 0.0 – 14.6

Females – Dose 2 0 192,380 0.0 0.0 – 15.6

12–15 years

Males – Dose 1 2 210,622 9.5 1.2 – 34.3

Males – Dose 2 31 203,420 152.5 103.6 – 216.4

Males – 1st Booster 1 59,483 17.0 0.4 – 94.9

Females – Dose 1 0 208,494 0.0 0.0 – 14.4

Females – Dose 2 5 201,638 24.8 8.1 – 57.9

Females - 1st Booster 0 61,876 0.0 0.0 – 48.4

16–17 years

Males – Dose 1 1 104,142 9.6 0.2 – 53.5

Males – Dose 2 14 100,980 138.7 75.8 – 232.8

Males – 1st Booster 8 40,177 200.3 86.5 – 394.7

Females – Dose 1 1 108,934 9.2 0.2 – 51.2

Females – Dose 2 1 105,929 9.4 0.2 – 52.6

Females - 1st Booster 2 45,794 44.0 5.3 – 159.0
Level of care and status of verified myocarditis and pericarditis case ages 5–17 years in 

the 0-7 days after primary series and 1st booster dose of mRNA COVID-19 vaccine, VSD

26

Level of care and status

Pfizer-BioNTech 

primary series

(n=58)

Pfizer-BioNTech 

1st booster

(n=12)

Highest level of care

Emergency department 4 (7%) 0 (0%)

Admitted to hospital 34 (59%) 6 (50%)

Admitted to ICU 20 (34%) 6 (50%)

Length of hospital stay, median (range) 2 days (0–7 days) 1 day (1–4 days)

0 – 1 days 20 (34%) 8 (67%)

2 – 3 days 28 (48%) 3 (25%)

4+ days 10 (17%) 1 (8%)

Discharged to home 58 (100%) 12 (100%)

Based on data through 

June 4, 2022
Comparative risk for myocarditis between the two available 

mRNA COVID-19 vaccines, Moderna and Pfizer-BioNTech

27
Presented at the October 21, 2021, ACIP meeting: https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2021-10-20-21/07-COVID-Su-508.pdf 28
Presented at the October 21, 2021, ACIP meeting: https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2021-10-20-21/07-COVID-Su-508.pdf 29
Presented at the October 21, 2021, ACIP meeting: https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2021-10-20-21/07-COVID-Su-508.pdf 30
Presented at the February 4, 2021, ACIP meeting: https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2022-02-04/10-COVID-Klein-508.pdf 31
Presented at the February 4, 2021, ACIP meeting: https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2022-02-04/10-COVID-Klein-508.pdf 32
Presented at the February 4, 2021, ACIP meeting: https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2022-02-04/10-COVID-Klein-508.pdf 33
VSD incidence rates of verified myocarditis/pericarditis 0–7 days following 

COVID-19 mRNA vaccination – December 14, 2020–March 31, 2022

34

(Adults ages 18-39 years)

Pfizer-BioNTech* Moderna†

Incidence rate per

million doses admin

Incidence rate per

million doses admin

18–29 years

Males – Dose 1 11.5 24.1

Males – Dose 2 81.7 97.3

Males – 1st Booster 47.6 70.3

Females – Dose 1 2.4 3.9

Females – Dose 2 5.0 0.0

Females - 1st Booster 4.7 13.9

30–39 years

Males – Dose 1 2.8 4.5

Males – Dose 2 14.7 37.0

Males – 1st Booster 16.5 7.1

Females – Dose 1 0.0 3.8

Females – Dose 2 7.3 3.9

Females - 1st Booster 4.0 11.1

* Pfizer dose totals, all ages/sexes: dose 1: 2,583,600, dose 2: 2,464,035, 1st booster: 997,217; 

† Moderna dose totals, all ages/sexes: dose 1: 950,608, dose 2: 914,745, 1st booster: 563,824
Summary: Myocarditis and pericarditis following mRNA COVID19 vaccination

35

 Current evidence supports a causal association between mRNA COVID-19 vaccines and 

myocarditis and pericarditis with cases clustering within the first week of vaccination

 Myocarditis is a rare event following mRNA COVID-19 vaccination

• CDC has verified 635 myocarditis case reports in children ages 5–17 years after 54.8 million 

Pfizer-BioNTech doses administered in this age group in the United States 

 Risk appears greatest in adolescents in the age groups 16–17 and 12–15 years and is generally 

higher after dose 2 compared to dose 1 of the primary series and in males compared to females

• In VSD analysis, in a minority of age and sex strata, incidence is highest following booster dose

 The reporting rate in VAERS of myocarditis following Pfizer-BioNTech in male children ages 5–11 

years after dose 2 of the primary series is slightly elevated when compared to background 

incidence; otherwise, reporting rates are within background incidence

 To date, myocarditis and pericarditis has not statistically signaled in VSD RCA surveillance in 

children ages 5–11 years
Summary: Myocarditis and pericarditis following mRNA COVID19 vaccination (cont.)

36

 Available information suggests that most persons with myocarditis after 

mRNA COVID-19 vaccination recover from their myocarditis by 90+ days 

after diagnosis

 In age groups where product comparisons can be made (e.g., 18–39 years), 

some evidence suggests that myocarditis and pericarditis risk may be 

higher after Moderna than after Pfizer-BioNTech; however, findings are not 

consistent in all U.S. monitoring systems
Acknowledgments

37

 VAERS Team

 V-safe Team

 Clinical Immunization Safety Assessment 

(CISA) Project

 Vaccine Safety Datalink (VSD) Team

 CDC Immunization Safety Office

 CDC Infectious Diseases Pathology Branch

 COVID-19 Vaccine Task Force Data 

Monitoring and Reporting Group

 FDA/Center for Biologics Evaluation and 

Research

 Kaiser Permanente Northern California (VSD)

 Marshfield Clinic Research Institute (VSD)

 VSD sites

• HealthPartners Institute, Minneapolis, MN

• Kaiser Permanente Colorado, Denver, CO

• Kaiser Permanente Northwest, Portland, OR

• Kaiser Permanente Southern California, Los Angeles, CA

• Kaiser Permanente Washington, Seattle, WA

• Denver Health, Denver, CO
Promoting v-safe in practice– we need help!

How:

 Direct patients to https://vsafe.cdc.gov/en/

• Ideally this should occur before vaccination

 Provide v-safe information sheet to patients

 Display posters about v-safe 

https://www.cdc.gov/coronavirus/2019ncov/vaccines/safety/vsafe/printresources.html
39

7 participating medical 

research centers with 

vaccine safety experts

†More information about clinical consults available at: 

http://www.cdc.gov/vaccinesafety/Activities/CISA.html

CISA 

Clinical

Immunization

Safety

Assessment 

(CISA) Project 

 clinical consult services

†

 clinical research
Disclaimer

 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 (CDC) or the U.S. Food and Drug 

Administration (FDA)

 Mention of a product or company name is for identification 

purposes only and does not constitute endorsement by CDC or FDA

40
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!