Heart Problems After Vaccination Are Very Rare, Federal Researchers Say

More than 1,200 cases have been reported, mostly mild and more often in young men and boys. The benefits of vaccination still far outweigh the risks, experts said.

The coronavirus vaccines made by Pfizer-BioNTech and Moderna may have caused heart problems in more than 1,200 Americans, including about 500 who were younger than age 30, according to data reported on Wednesday by researchers at the Centers for Disease Control and Prevention. Still, the benefits of immunization greatly outweighed the risks, and advisers to the C.D.C. strongly recommended vaccination for all Americans 12 and older. The heart problems reported are myocarditis, an inflammation of the heart muscle; and pericarditis, inflammation of the lining around the heart. The risk is higher after the second dose of an mRNA vaccine than after the first, the researchers reported, and much higher in men than in women.