A complete evidence review of the documented association between mRNA COVID-19 vaccines and myocarditis
Myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the lining around the heart) have been identified as rare but documented adverse events following mRNA COVID-19 vaccination. This page presents the evidence transparently — including incidence rates, risk factors, clinical course, and comparison to COVID-19-associated myocarditis.
This is a confirmed, established adverse event recognised by the CDC, FDA, WHO, and other major regulatory agencies worldwide.
Multiple studies and surveillance systems have documented the incidence of vaccine-associated myocarditis. The highest rates are observed in young males after the second dose.
| Age Group | Sex | Dose | Estimated Rate (per million doses) |
|---|---|---|---|
| 12–17 years | Male | 2nd dose | 70–105 |
| 18–24 years | Male | 2nd dose | 50–80 |
| 12–17 years | Female | 2nd dose | 8–12 |
| 18–24 years | Female | 2nd dose | 5–10 |
| 65+ years | Both | Any | 1–3 |
Source: CDC surveillance data, ACIP presentations (2021–2022). Rates may vary based on case definition, surveillance method, and time period. These are estimates — see sources for full methodology.
Important note on detection: Enhanced surveillance (including active hospital-based monitoring) detects more cases than passive reporting alone. The true incidence may be higher than currently estimated due to mild or asymptomatic cases that go undetected.
Research consistently shows that the risk of myocarditis from SARS-CoV-2 infection is higher than from vaccination:
Added a warning about myocarditis/pericarditis to Emergency Use Authorizations for Pfizer-BioNTech and Moderna COVID-19 vaccines. Warning retained in full approval labelling.
Recommended updated guidance for clinicians and updated screening considerations. Noted that benefits of vaccination continue to outweigh risks while monitoring continues.
Noted that benefits of vaccination continue to outweigh risks across population groups, but advised continued monitoring and updated guidance for clinicians.
Added myocarditis and pericarditis to the Product Information for mRNA vaccines with revised guidance for healthcare professionals.
CDC. "Myocarditis and Pericarditis After COVID-19 Vaccination." Centers for Disease Control and Prevention. 2022.
https://www.cdc.gov/coronavirus/2019-ncov/vaccines/safety/myocarditis.htmlPatone M, et al. "Risks of myocarditis, pericarditis, and cardiac arrhythmias associated with COVID-19 vaccination or SARS-CoV-2 infection." Nature Medicine. 2022;28:410-422.
https://doi.org/10.1038/s41591-021-01630-0Witberg G, et al. "Myocarditis after Covid-19 Vaccination in a Large Health Care Organization." New England Journal of Medicine. 2021;385:2132-2139.
https://doi.org/10.1056/NEJMoa2110737Li R, et al. "Myocarditis and Other Cardiovascular Complications of the mRNA-Based COVID-19 Vaccines." Cureus. 2021;13(6):e15400.
https://doi.org/10.7759/cureus.15400FDA. "Comirnaty and Paxlovid: FDA-Approved Products." U.S. Food and Drug Administration.
https://www.fda.gov/emergency-preparedness-and-response/coronavirus-disease-2019-covid-19/comirnaty-and-paxlovid-fda-approved-productsOverview of vaccine safety monitoring systems.
US Vaccine Adverse Event Reporting System.
Documented adverse events by vaccine type.
WHO AEFI and international pharmacovigilance.
National Vaccine Injury Compensation Program.