Although cases of myocarditis or pericarditis temporally tied to COVID-19 vaccination are rare, they may be more common than reported, suggests a review of electronic medical records (EMR).

According to George Diaz, MD, Providence Regional Medical Center Everett, Washington, they seem to represent two distinct syndromes. While myocarditis usually occurs soon after vaccination in younger individuals and mostly following the second dose, pericarditis seems to occur later in older patients, after either the first shot or the second.

Investigators looked at the records of 2,000,287 individuals who received at least one vaccination at 40 hospitals in Washington, Oregon, Montana, and California. Around 77% of the individuals had received more than one dose; most received the Pfizer (53%) and Moderna (44%) vaccines; about 3% received the Johnson & Johnson vaccine. According to the records, 20 individuals developed vaccine-related myocarditis, i.e., 1 per 100,000, while 37 developed pericarditis, which amounts to 1.8 per 100,000. The findings are published online August 4 in JAMA… (Medscape)