SARS-CoV-2 vaccination and myocarditis or myopericarditis: population based cohort study

OBJECTIVE To investigate the association between SARS-CoV-2 vaccination and myocarditis or myopericarditis. DESIGN Population based cohort study. SETTING Denmark. PARTICIPANTS 4 931 775 individuals aged 12 years or older, followed from 1 October 2020 to 5 October 2021. MAIN OUTCOME MEASURES The primary outcome, myocarditis or myopericarditis, was defined as a combination of a hospital diagnosis of myocarditis or pericarditis, increased troponin levels, and a hospital stay lasting more than 24 hours. Follow-up time before vaccination was compared with follow-up time 0-28 days from the day of vaccination for both first and second doses, using Cox proportional hazards regression with age as an underlying timescale to estimate hazard ratios adjusted for sex, comorbidities, and other potential confounders. RESULTS During follow-up, 269 participants developed myocarditis or myopericarditis, of whom 108 (40%) were 12-39 years old and 196 (73%) were male. Of 3 482 295 individuals vaccinated with BNT162b2

Automated summary

This study investigated the association between SARS-CoV-2 vaccination and myocarditis or myopericarditis, finding an increased risk of developing these conditions within 0-28 days post-vaccination, especially among individuals aged 12-39 and males.