Incidence of Myocarditis Before and After SARS-CoV-2 Vaccination and Infection in Canterbury, 2016–2022

To compare the incidence of myocarditis in Canterbury before SARS-CoV-2 pandemic, during a period high vaccination uptake, and widespread community transmission. Adult patients admitted to Christchurch Hospital between 2016 2022 who received diagnostic code acute (ICD10 codes I40, I41, I51.4) were included. Demographic data, peak troponin concentration (hs-cTn), mortality, recent vaccination, or positive test recorded. Incidence background (2016–2020), (2021), transmission (2022) phases compared using Pearson’s Chi-squared test. Background admission was seven per 100,000 population/year (CI 6–8.2); mean age 47 [SD 16] years; 36% women; there one death <28 days admission. Vaccination phase 8.5 6.2–11.6); 49 19] 46% eight (20%) admissions within 28 person died. Community 13.1 10.2–16.9); 50 21] 48% (44%) cases associated with active infection; four died—three from COVID-19. There no variance annual vaccine rollout 2016–2020 (p=0.5). The infection higher than previous years (p=0.001). an increased diagnosis when rates transmission, almost half which infection. increase alone.