Abstract 10071: Myocarditis in SARS-CoV-2 Infection versus COVID-19 Vaccination: A Systematic Review and Meta-Analysis

Abstract

Introduction: COVID-19 infection and vaccines are associated with acute myocarditis. However, the relative risk of myocarditis is not fully characterized. The aim of this study is to compare the risk ratio (RR) of myocarditis in COVID-19 vaccines and SARS-CoV-2 infection groups and to delineate the effect modifiers. Hypothesis: Risk ratio of myocarditis is higher in the infection group than in the vaccinated group, and this risk is modified by age and sex. Methods: Multiple electronic databases and trial registries were searched to April 2022, for randomized controlled trials and observational cohort studies reporting the risk of myocarditis associated with the COVID-19 vaccines and the risk associated with SARS-CoV-2 infection. We estimated the effect of COVID-19 infection and vaccines on rates of myocarditis by random-effects meta-analyses using the generic inverse variance method. Meta-regression analyses were conducted to assess the effect of sex and age on the incidence of myocarditis. Results: 22 eligible studies consisting of 55.5 million in the vaccinated cohort and 2.5 million in the infection cohort were included. Median age was 49 years (interquartile range (IQR): 38-56), and 49% (IQR: 43% to 52%) were male. Of patients diagnosed with myocarditis, 3.48% were hospitalized and 0.05% died. The RR for myocarditis in the infection group was15 (95% CI: 11.09 - 19.81) and 2.0 (95% CI: 1.44-2.65) in the vaccine group. Of patients who developed myocarditis after receiving the vaccine or having the infection, 61% (IQR: 39% -87%) were male. Meta-regression analysis indicated that male sex and young age were associated with myocarditis. Risk of bias assessment was moderate. Conclusions: In this systematic review and meta-analysis, we found that the risk of incident myocarditis is about 7 times higher in persons who were infected with SARS-CoV-2 virus than in those who received the vaccine.