C.D.C. Is Investigating a Heart Problem in a Few Young Vaccine Recipients

The agency is reviewing several dozen reports that teenagers and young adults may have developed myocarditis after vaccination, officials said. But the agency has not determined whether the vaccine caused the condition.

The Centers for Disease Control and Prevention is looking into reports that a very small number of teenagers and young adults vaccinated against the coronavirus may have experienced heart problems, according to the agency’s vaccine safety group. The group’s statement was sparse in details, saying only that there were “relatively few” cases and that they may be entirely unrelated to vaccination. The condition, called myocarditis, is an inflammation of the heart muscle, and can occur following certain infections. The C.D.C.’s review of the reports is in the early stages, and the agency has yet to determine whether there is any evidence that the vaccines caused the heart condition. The agency has posted guidance on its website urging doctors and clinicians to be alert to unusual heart symptoms among young people who had just received their shots.