When is Myocarditis Most Severe? 2 Questions on Etiology

Terry Brenneman, MD

Fairly soon after the use of the mRNA COVID vaccines from Moderna and Pfizer became widespread, the true risk of myocarditis associated with vaccine receipt became apparent, with young men being at highest risk. It was also known that infection with the SARS-CoV-2 virus could cause clinically significant myocarditis.

A meta-analysis published in 2022 looked at 22 studies (some RCT and some observational cohort) that included 55 million vaccinated individuals and 2.5 million COVID-infected persons. Both sexes have an increased risk but men and younger persons were at highest risk. The study concluded that the risk of myocarditis was 7 times higher in COVID- infected persons than in persons who developed the inflammatory condition after COVID vaccination. Another study, performed by the Centers for Disease Control and Prevention, found a 16-fold increased risk of myocarditis from COVID disease when compared to vaccination.

Myocarditis can be totally asymptomatic. At the other end of the clinical spectrum, however, myocarditis can be fatal, with arrhythmias, heart failure, heart attacks, and stroke all possible sequelae. Let's see what you know about “conventional” myocarditis.