C.D.C. advisers are expected to discuss rare heart problems in vaccinated younger people.

The majority of cases have been mild, with symptoms like fatigue, chest pain and disturbances in heart rhythm that quickly clear up.

source https://www.nytimes.com/2021/06/23/health/cdc-advisers-are-expected-to-discuss-rare-heart-problems-in-vaccinated-younger-people.html