Heart inflammation after COVID vaccine may be more common than thoughtMyocarditis and pericarditis both saw increased prevalence in COVID-19 vaccine recipients compared with a pre-vaccine period of January 2019 to January 2021, with the incidence still rare but higher than in previous studies, according to a JAMA research letter yesterday.The researchers used electronic medical records from 40 hospitals in Washington, Oregon, Montana, and Los Angeles County to look at data from 2,000,287 people who received at least one COVID-19 vaccination from February to May 2021.Twenty people had vaccine-related myocarditis (1.0 per 100,000 people) and 37 had pericarditis (1.8 per 100,000).