An analysis of studies comparing myocarditis and pericarditis in COVID-19 vaccinated and SARS-CoV-2 infected individuals.

We sought to identify studies that examined myocarditis and pericarditis after both COVID-19 vaccination and SARS-CoV-2 infection. A literature search was conducted, and retrospective cohort studies examining incidence rates for myocarditis and pericarditis after both COVID-19 vaccination and SARS-CoV-2 infection were included. The methodologies and conclusions of each study was assessed, and a risk of bias was determined. We found 6 articles that utilized cohorts of both vaccinated and infected populations. Of the included articles, all of them had risk of bias concerns, with 50 % having a poor-quality rating and 50 % having a fair quality rating. Methodological biases, including reliance on electronic health record data, inadequate observational periods, and failure to account for baseline characteristics between the two cohorts, were observed across studies. Ultimately, these methodological limitations lead to hyperinflated myocarditis rates in the infection cohorts and a lack of meaningful comparisons between the infection and vaccination cohorts.