Heart inflammation requiring hospital care was more common among people who received COVID-19 vaccines than those who did not, according to a new study of tens of millions of Europeans.Rates of myocarditis or pericarditis, two types of heart inflammation, are above the levels in an unvaccinated cohort, pegged at 38 per 100,000 after receipt of a second dose of a vaccine built on messenger RNA (mRNA) technology in males aged 16 to 24—the group studies have shown are most at risk of the post-vaccination condition—researchers with health agencies in Finland, Denmark, Sweden, and Norway found.“These extra cases among men aged...