Myocarditis.

VAERS data from December 2020 to August 2021 reveals the lower estimate of the 95% CI for confirmed cases of myocarditis exceeded the upper bound of expected rates in males after the first Pfizer (ages 12-24) and Moderna (18-39) vaccines and especially after the second Pfizer (12-49) and Moderna (18-49) vaccines, with both symptom onset and resolution occurring more quickly—usually within days—than typically seen. | Oster, JAMA 2022