Incidence of Myocarditis/Pericarditis Following mRNA COVID-19 Vaccination Among Children and Younger Adults in the United States

In this population-based surveillance, the authors found that myocarditis/pericarditis 0 to 7 days after mRNA vaccination in persons aged 5 to 39 years occurred in approximately 1 in 200,000 doses after the first dose and 1 in 30,000 doses after second dose of the primary series, and 1 in 50,000 doses after the first booster. The incidence varied markedly by age and sex, however, with a disproportionate number of cases occurring in male persons, notably among adolescents after dose 2 and first boosters.