evidence: England’s National Immunization database records were then cross-referenced and matched to the national offices with data on COVID-19 infection, hospital admission and death certificates for the same time period, December 1, 2020 through December 15, 2021. Individuals were classified based on age and sex to reveal which groups had the highest risk of myocarditis after a COVID-19 vaccine or after COVID-19 infection and hospitalization. The authors used the self-controlled case series (SCCS) method, which was developed to estimate the relative incidence of an acute event in a pre-defined post-vaccination risk period (1-28 days), compared to other times (pre-vaccination or long after vaccination). Being a within-person comparison, the analyses were controlled to adjust for any fixed characteristics, including sex, race or ethnicity, or chronic health conditions. [...] - An increased risk of vaccine-associated myocarditis was found in men ages 40 and younger after a first dose of either of the mRNA COVID-19 vaccines (4 and 14 estimated extra cases for every one million men vaccinated with respectively Pfizer or Moderna vaccine), or a second dose of any of the three COVID-19 vaccines available in England during the study period: 14, 11 and 97 estimated additional cases of myocarditis for every one million men vaccinated, respectively for the ChAdOx1, the Pfizer-BioNTech or the Moderna vaccine.