The Food and Drug Administration directed manufacturers to update the labels.
Federal regulators on June 25 updated labels for the Pfizer-BioNTech and Moderna COVID-19 vaccines to expand warnings regarding heart inflammation.
The updatedlabels state that myocarditis, inflammation, and a related condition called pericarditis have occurred following receipt of one of the shots “most commonly in males 12 years through 24 years of age.”
The Food and Drug Administration said in letters to the vaccine manufacturers earlier this year that they should update warnings on the inflammation to reflect available information.
The previous labels said that the highest observed risk of myocarditis after Pfizer vaccination was in males aged 12 to 17 while the highest observed risk following Moderna vaccination was in males aged 18 to 24.
Richard Forshee, acting director of the FDA’s Office of Biostatistics and Pharmacovigilance pointed to newer research, including a 2024 FDA study that found that some myocarditis patients had signs of heart scarring months after vaccination.
The vaccine makers could have challenged the directives, but instead opted to revise the labeling to comply with them, according to letters made public on Wednesday.
Pfizer, BioNTech, and Moderna did not return inquiries. The vaccines from the companies were the first to use messenger ribonucleic acid (mRNA) technology and receive clearance in the United States.
They were administered to hundreds of millions of people during the COVID-19 pandemic, and some people continue to receive the vaccines.
“Continuous monitoring and assessment of the safety of all vaccines, including the mRNA COVID-19 vaccines, is an FDA priority and we remain committed to informing the public when we learn new information about these vaccines,” the FDA said in a statement.
As part of the approvals of the vaccines, the manufacturers are also conducting studies assessing the long-term impacts on the hearts of recipients.
The new labels state that the estimated incidence of myocarditis or pericarditis within seven days of a dose of one of the vaccines is eight cases per million doses in people ages 6 months through 64, and 27 cases per million doses in males ages 12 to 24.
