Incidence of Myopericarditis and Myocardial Injury in Coronavirus Disease 2019 Vaccinated Subjects

Several recent publications have described myopericarditis cases after the coronavirus disease 2019 (COVID-19) vaccination. However, it is uncertain if these cases occurred secondary to the vaccination or more common etiologies of myopericarditis. To help determine whether a correlation exists between COVID-19 vaccination and myopericarditis, the present study compared the gender-specific cumulative incidence of myopericarditis and myocardial injury in a cohort of COVID-19 vaccinated patients at a tertiary care center in 2021 with the cumulative incidence of these conditions in the same subjects exactly 2 years earlier. We found that the age-adjusted incidence rate of myopericarditis in men was higher in the vaccinated than the control population, rate ratio 9.7 (p = 0.04). However, the age-adjusted incidence rate of myopericarditis in women was no different between the vaccinated and control populations, rate ratio 1.28 (p = 0.71). We further found that the rate of myocardial injury was higher in both men and women in 2021 than in 2019 both before and after vaccination, suggesting that some of the apparent increase in the diagnosis of myopericarditis after vaccination may be attributable to factors unrelated to the COVID-19 vaccinations. In conclusion, our study reaffirms the apparent increase in the diagnosis of myopericarditis after COVID-19 vaccination in men but not in women, although this finding may be confounded by increased rates of myocardial injury in 2021. The benefits of COVID-19 vaccination to individual and public health clearly outweigh the small potential increased risk of myopericarditis after vaccination.