Vaccine-associated Myo/pericarditis

Page last updated 17 August 2022

Key Points

Key Points are meant to be a scientific, factual summary of the available information that relates solely to the Pfizer-BioNTech COVID-19 Vaccine, as supported by referenced publications within this section. Conclusions should not be drawn from the inclusion or absence of information.

Vaccine-related Myo/pericarditis Key Points References
Epidemiology
  • Epidemiological studies have reported an increased risk of myo/pericarditis after mRNA COVID-19 vaccination.1–14
    • The estimated incidence* of BNT162b2 vaccine-related myo/pericarditis, per 100,000 persons, was observed to be:
      • Myocarditis:
        • Risk difference (per 100,000 persons):
          • Between 1st and 2nd doses- 1.76 cases in ages ≥ 16 years, with the largest observed risk difference of 13.73 cases among males ages 16–19 years, 21 days post-vaccination.6
          • Between vaccinated and unvaccinated persons- 2.7 events, in age ≥ 16 years, 42 days post-vaccination.1
        • Cases (per 100,000 persons):
          • 2.13 cases in vaccinated persons aged ≥ 16 years, with the highest observed rates of 10.69 cases in ages 16–29 years.11
      • Pericarditis:
        • Risk difference (per 100,000 persons):
          • Between vaccinated and unvaccinated persons- 0.98 events, in age ≥ 16 years (42 days post-vaccination).1
      • Myo/pericarditis:
        • Cases (per 100,000 persons), highest observed rates:
          • 35.9 and 6.5 cases in males ages 12–17 (21 days post 2nd dose) and 5–11 years (unspecified dose), respectively.12
          • 5.4 cases in females ages 12–17, 21 days post 2nd dose. No cases were reported in females ages 5–11 years.12
    • The estimated incidence of SARS-CoV-2-related myo/pericarditis, per 100,000 persons, was observed to be:
      • Myo/pericarditis:
        • Risk difference (per 100,000 persons):
          • Between vaccinated and unvaccinated persons- 11 events, in age ≥ 16 years, 42 days after SARS-CoV-2 infection.1
        • Cases (per 100,000 persons), highest observed rates:
          • 65 and 17.6 cases in males ages 12–17 years and 5–11 years, respectively, with risk window of 21 days.12
          • 35.7 and 10.8 cases in females ages 12–17 years and 5–11 years, respectively, with risk window of 21 days.12
    • The estimated number of excess events of myo/pericarditis attributable to BNT162b2 vaccine, per 100,000 doses administered14 or per 100,000 vaccinees13, were observed to be:
      • 1.39 and 0.31 excess events in males and females, respectively, with the highest observed rate of 8.3 excess events in male 16–24 years, 28 days post 2nd dose.13
      • 1.9 excess events in males ages 12–17 years and 4.7 excess events in participants ages 18–24 years, 7 days post 2nd dose.14
  • Association of myo/pericarditis with COVID-19 viral infection has been reported and at higher rates than after mRNA COVID-19 vaccination.1,12
  • The myo/pericarditis reporting rate is very rare.3,7,10

(1) Barda; (2) Gargano; (3) Husby; (4) Klein; (5) Mevorach, NEJM 2022: (6) Mevorach, NEJM 2021; (7) Oster; (8) Patone; (9) Rosenblum; (10) Simone; (11) Witberg; (12) Block; (13) Karlstad; (14) Le Vu

 
Risk Factors
  • The risk of COVID-19 vaccine-related myo/pericarditis appears to be higher in certain subpopulations:
    • In male adolescents 12–17 years of age (60–82% of cases) and young adults < 39 years.1–3,5–8,10–13
    • After the 2nd dose of mRNA vaccine and within the first 7 days of vaccination.3–7,10

(1) Barda; (2) Gargano; (3) Husby; (4) Klein (5) Mevorach, NEJM 2022; (6) Mevorach, NEJM 2021; (7) Oster; (8) Patone; (10) Simone; (11) Witberg; (13) Karlstad; (14) Le Vu
Clinical course, severity, and complications
  • The majority of observed cases were mild (76–95%) and recovered (87%).2,5–7,12
  • Disease severity, duration, and complications appear to be decreased in mRNA vaccine-related myo/pericarditis when compared to classic viral or SARS-CoV-2-related myo/pericarditis.12

(2) Gargano; (5) Mevorach, JAMA 2021; (6) Mevorach, NEJM 2022; (7) Oster;  (12) Block
Current recommendations
  • CDC continues to recommend COVID-19 vaccination for everyone 6 months of age and older given the risk of COVID-19 illness and related, possibly severe complications, such as long-term health problems, hospitalization, and even death.16
  • An 8-week interval between the 1st and 2nd doses of BNT162b2 may be optimal for some individuals ages 6 months–64 years, especially for males ages 12–39 years, as it may reduce the small risk of vaccine-related myocarditis.16,17
  • A shorter interval of 3 weeks between the 1st and 2nd doses remains the recommended interval for those who are moderately or severely immunocompromised; adults ages ≥ 65 years; and when there is increased concern about COVID-19 community levels or an individual’s higher risk of severe disease. 16,17

(15) Clinical Considerations: Myocarditis and Pericarditis after receipt of mRNA COVID-19 Vaccines | CDC; (16) Use of COVID-19 Vaccines in the United States, Interim Clinical Considerations I CDC; (17) Interim COVID-19 Immunization Schedule for 6 months of age and older I CDC
 

* Major limitations estimated incidence of myo/pericarditis include the comparatively limited data available for both 5–11 year-olds and booster doses, relative to the primary series and booster doses in individuals 16 years and older, the inherent limitations of data in passive surveillance systems (such as VAERS, LAREB), the relatively low number of relevant reports in active surveillance systems, and a lack of background estimates (expected rates) for contextualization of the risk magnitude in some data sources. In addition, the studies listed have varying study designs and methodologies, and, therefore, cannot be compared.