evidence: Incidence, risk factors, natural history, and hypothesised mechanisms of myocarditis and pericarditis following covid-19 vaccination - 1Division of General Internal Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA - 2Center for Health Equity Research and Promotion, VA Pittsburgh Healthcare System, Pittsburgh, PA, USA - Correspondence to: J Luo luoj@pitt.edu [...] In this context, Pillay and colleagues (doi:10.1136/bmj-2021-069445)3 conducted a systematic review to examine incidence rates, risk factors, short term clinical course, and longer term outcomes of myocarditis and pericarditis after covid-19 mRNA vaccination. Among thousands of database citations through to 10 January 2022, their team ultimately focused on 46 studies. [...] In summary, a large body of reviewed studies continues to suggest that mRNA covid-19 vaccines are associated with a rare but heightened risk of acute myocarditis and pericarditis. These risks are highest in young males shortly after the second dose. Key uncertainties remain, including risks associated with boosters, risks associated with primary vaccination of young children, and the long term outcomes of those who experience myocarditis. But these uncertainties must be placed in the context of the substantial and widely accepted benefits of vaccination.