The COVID-19 pandemic changed the epidemiology of myocarditis and pericarditis in England: a 9-year population-based study of 50 million adults

Background Prior to the COVID-19 pandemic, myocarditis and pericarditis (myopericarditis) cases were largely sporadic, associated with heterogeneous and frequently unidentifiable viruses.1 The COVID-19 pandemic uniquely exposed entire populations to a single pathogen and mass vaccination. Despite extensive SARS-CoV-2 transmission and one of the world’s largest vaccination programmes, the population-level impact of the pandemic on myopericarditis incidence in England remains poorly defined. Purpose To quantify national temporal trends in myopericarditis incidence in England over 9 years (2015-2024) and evaluate the contributions of COVID-19 infection and vaccination in the largest primary care cohort studied to date. Methods Population-based retrospective cohort study using primary care records from Clinical Practice Research Datalink (CPRD) Aurum, including 50 million adults registered in English primary care.2-3 Incident myopericarditis cases were identified using diagnostic codes. Annual incidence rates were calculated across pre-pandemic and pandemic periods. Associations within 30 days of COVID-19 infection and vaccination were assessed using negative binomial regression, estimating adjusted incidence rate ratios (aIRR). Results Among 22,369 incident cases, myopericarditis incidence rose from 13.9 per 100,000 person-years in 2015 to a peak of 19.5 in 2022, and remained elevated at 18.7 through 2024, driven predominantly by myocarditis. COVID-19 infection conferred an 8-fold increase in incidence (aIRR 8.54, 95% CI 7.89–9.22), substantially exceeding the risk associated with mRNA vaccination (Moderna dose 1: aIRR 3.54, 95% CI 2.23–5.31, dose 2 aIRR 3.38, 95% CI 1.98–5.06 and BNT162b2 dose 1: aIRR 1.47, 95% CI 1.20–1.79, dose 2 aIRR 1.87, 95% CI 1.54–2.24). Male sex was independently associated with a higher incidence (aIRR 2.09, 95% CI 2.02–2.15). However, pandemic-era increases were disproportionately concentrated among groups not traditionally considered high-risk: the relative increase was markedly greater among females (+35.8%) than males (+9.4%), with the largest rises observed in women aged 36-40 (+69.4%) and adults aged 66–70 (+38.0%), compared with modest increases (+10%) among those aged 16–35. Conclusion The COVID-19 pandemic produced a sustained shift in the epidemiology of myopericarditis in England. COVID-19 infection was the dominant driver of the increase in incidence. Beyond increased absolute rates, the pandemic period was characterised by a relative shift toward greater increases in females and older adults. Understanding the persistent increase in myopericarditis rates is critical for future service planning. Post-pandemic surveillance and clinical vigilance should extend beyond the traditionally recognised young male demographic.figure1figure2