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Risk of Myocarditis After Sequential Doses of COVID-19 Vaccine and SARS-CoV-2 Infection by Age and Sex
Martina Patone1, Xue W Mei1, Lahiru Handunnetthi2
1Nuffield Department of Primary Health Care Sciences (M.P., X.W.M., S.D., A.H., C.A.C.C., J.H.-C.), University of Oxford.
Circulation
|August 22, 2022
Summary
Myocarditis risk is higher after COVID-19 infection than vaccination. While generally modest after COVID-19 vaccination, younger men face increased risk, especially after the mRNA-1273 vaccine second dose.
Area of Science:
- Immunology
- Infectious Diseases
- Cardiology
Background:
- Myocarditis, inflammation of the heart muscle, is a known complication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.
- The comparative risk of myocarditis following COVID-19 vaccination versus SARS-CoV-2 infection, particularly in younger populations and after multiple vaccine doses, requires further investigation.
Purpose of the Study:
- To assess the association between COVID-19 vaccination (adenovirus and mRNA-based vaccines) and myocarditis.
- To compare the risk of myocarditis after vaccination with the risk following SARS-CoV-2 infection.
- To evaluate age and sex-specific risks, especially in younger individuals and after sequential vaccine doses.
Main Methods:
- A self-controlled case series study was conducted in England, analyzing data from individuals aged 13 years and older vaccinated between December 2020 and December 2021.
- The study evaluated myocarditis events within 28 days following vaccination (ChAdOx1, BNT162b2, mRNA-1273) or SARS-CoV-2 infection.
- Incidence rate ratios and excess events per million people were calculated, stratified by age, sex, and vaccine type/dose.
Main Results:
- Myocarditis occurred in 0.007% of vaccinated individuals, with 617 events within 28 days post-vaccination.
- Increased myocarditis risk was observed after first dose of ChAdOx1 and first, second, and booster doses of BNT162b2.
- The risk of myocarditis was significantly higher after SARS-CoV-2 infection compared to vaccination. A notable increase in risk was seen after the second mRNA-1273 dose, particularly in men under 40.
Conclusions:
- COVID-19 infection poses a greater risk of myocarditis than COVID-19 vaccination.
- The risk of myocarditis following vaccination, including sequential doses and boosters, is generally modest.
- Younger men exhibit a higher risk of myocarditis post-vaccination, especially after the second mRNA-1273 dose, warranting specific attention.
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