The FDA updated its fact sheet for healthcare providers about Johnson & Johnson's COVID-19 vaccine to include warnings of myocarditis and pericarditis.
Myocarditis is inflammation of the heart and pericarditis is inflammation of the lining outside the heart. Both are listed as potential risks of the vaccine, and the FDA said symptoms typically happen within eight days of inoculation. The risk is very low, the agency said.
People who receive the vaccine and experience chest pain, shortness of breath, or feelings of having a fast-beating, fluttering or pounding heart are instructed to seek immediate medical attention.
The agency made the revision on March 13, about 10 months after the FDA limited the shot's use after worries of a blood clot risk. The shot makes up a small share of all COVID-19 vaccinations: Nearly 19 million J&J shots have been administered, while 475 million of Pfizer's and Moderna's vaccines have been used, according to the CDC.