(HealthDay News) — The overall risk for myocarditis is higher after a positive SARS-CoV-2 test than after COVID-19 vaccination, according to a study published online Aug. 22 in Circulation.

Martina Patone, Ph. D., from the Nuffield Department of Primary Health Care Sciences in Oxford, England, and colleagues estimated the incidence rate ratio and excess number of hospital admissions or deaths from myocarditis per million people (aged 13 years or older) for the one to 28 days following adenovirus (ChAdOx1) or mRNA-based (BNT162b2 or mRNA-1273) vaccine doses or following a positive SARS-CoV-2 test.

Data were included for 42,842,345 people receiving at least one dose of vaccine, 21,242,629 of whom received three doses; 5,934,153 had SARS-CoV-2 infection before or after vaccination.

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The researchers found that 2,861 people (0.007 percent) had myocarditis, with 617 events one to 28 days after vaccination. Elevated myocarditis risk was seen at one to 28 days after a first dose of ChAdOx1 (incidence rate ratio, 1.33) and a first, second, and booster dose of BNT162b2 (incidence rate ratios, 1.52, 1.57, and 1.72, respectively), but was lower than after a positive SARS-CoV-2 test before or after vaccination (incidence rate ratios, 11.14 and 5.97, respectively).

Myocarditis risk was elevated after a second dose of mRNA-1273, which persisted after the booster dose (incidence rate ratios, 11.76 and 2.64, respectively). For all vaccines, the associations were stronger in men younger than 40 years.

“Our hope is that [these] data may enable a more well-informed discussion on the risk of vaccine-associated myocarditis when considered in contrast to the net benefits of COVID-19 vaccination,” a coauthor said in a statement.

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