mRNA COVID vaccines can rarely cause heart inflammation
COVID vaccines protect against serious illness. Myocarditis after mRNA vaccination is rare, even in young men. Most hospitalized patients’ initial symptoms resolve by discharge. Studies generally find higher myocarditis risk after COVID infection than vaccination, with exceptions by age, vaccine and dose.
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Studies generally find greater myocarditis risk after infection
Large studies in England and Israel found greater myocarditis risk after COVID infection overall than after vaccination. The English study included more than 42 million people in 2020–2021. An important exception was men under 40 after a second dose of original Moderna: 97 extra myocarditis hospital admissions or deaths per million, versus 16 after a positive test before vaccination, in the same 28-day window. These historical estimates are not today’s booster rates or a complete comparison of vaccination’s benefits and harms.
Rare even in the higher-risk group
The highest risk is in adolescent and young adult males, but the absolute risk remains low. After 2023–24 mRNA doses, FDA estimated about 27 myocarditis or pericarditis cases per million doses in males aged 12–24 during days 1–7, compared with 8 per million among ages 6 months–64. Myocarditis affects the heart muscle; pericarditis affects its surrounding lining. These are observed rates before adjustment, not extra cases proven to be caused by vaccination. They cannot be compared directly with the English study’s 28-day estimates.
Symptoms usually improve early; follow-up still matters
In a US study of 2020–2021 reports, 87% of discharged patients under 30 with available symptom information—577 of 661—had their initial symptoms resolve by discharge. Feeling better does not necessarily mean the heart has fully recovered. A French 18-month study found better outcomes after vaccine-associated myocarditis than in other myocarditis groups, although some patients needed ongoing care. FDA reports persistent scan findings in some patients; their long-term meaning is uncertain.
Vaccination protects against more than heart inflammation
Vaccination reduces serious COVID illness, including hospital treatment. That protection belongs in the decision alongside the rare heart risk. Checked 15 October 2026: CDC recommends 2026–27 COVID vaccination for US adults. A personal decision also considers age, health, prior immunity, product, dose and previous reactions. Discuss a history of myocarditis or current symptoms with a clinician.
Vaccination protects against serious COVID. Myocarditis is rare, and initial symptoms usually improve by discharge; follow-up can still be needed.
Keep in mind
- The findings apply to the vaccines, populations and outcomes studied. Personal recommendations depend on your health and current local guidance.
Sources you can check
Publication links open in a new tab, so you can keep your place here.
FDA Approves Required Updated Warning in Labeling of mRNA COVID-19 Vaccines Regarding Myocarditis and Pericarditis Following Vaccination (opens in a new tab)
FDA, June 2025
Observed 2023–24-formulation incidence in days 1–7 is not an excess-risk estimate. Persistent MRI findings have uncertain long-term meaning.
Return to reading ↑Risk of Myocarditis After Sequential Doses of COVID-19 Vaccine and SARS-CoV-2 Infection by Age and Sex (opens in a new tab)
Circulation, 2022
Historical English estimates use 28-day windows and vary by age, sex, product and dose; not current booster rates.
Return to reading ↑Long-Term Prognosis of Patients With Myocarditis Attributed to COVID-19 mRNA Vaccination, SARS-CoV-2 Infection, or Conventional Etiologies (opens in a new tab)
JAMA, 2024
French hospitalized patients followed for 18 months. Better average outcomes do not mean every patient recovered completely.
Return to reading ↑Interim Estimated Effectiveness of 2025–2026 COVID-19 Vaccines in Adults Using a Test-Negative Design (opens in a new tab)
JAMA Network Open, 2026
US immunocompetent adults, September–December 2025; compares a current-season dose with none, with short follow-up.
Return to reading ↑Myocarditis Cases Reported After mRNA-Based COVID-19 Vaccination in the US From December 2020 to August 2021 (opens in a new tab)
JAMA, 2022
US reports from 2020–2021. Among discharged patients under 30 with symptom information, 577 of 661 had presenting symptoms resolve. This does not establish complete heart recovery.
Return to reading ↑Safety of the BNT162b2 mRNA Covid-19 Vaccine in a Nationwide Setting (opens in a new tab)
New England Journal of Medicine, 2021
Historical Israeli matched comparisons found more excess myocarditis after documented infection than Pfizer vaccination; separate comparison groups, not a randomized trial or current booster estimate.
Return to reading ↑Interim Clinical Considerations for Use of COVID-19 Vaccines in the United States (opens in a new tab)
CDC, September 2026
US 2026–27 recommendations, checked 15 October 2026. Recommendations and FDA-approved indications are distinct; clinical exceptions and local guidance matter.
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Detailed research notes and source data
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These pages have not completed expert review. For personal vaccine advice, talk to a clinician who knows your circumstances.
Research checked: . Wording reviewed: 2026-10-15. Version: vaccine-2026-10-15-myocarditis.
We revisit the page when new evidence or corrections change the answer. A public history of corrections is not available yet.