After mRNA-Based COVID-19 Vaccination
in the US From December 2020 to August 2021

Conclusions and relevance: Based on passive surveillance reporting in the US, the risk of myocarditis after receiving mRNA-based COVID-19 vaccines was increased across multiple age and *** strata and was highest after the second vaccination dose in adolescent males and young men. This risk should be considered in the context of the benefits of COVID-19 vaccination. DOI: 10.1001/jama.2021.24110