FDA Updates Pfizer, Moderna COVID Vaccine Labels with Expanded Myocarditis Warnings

The U.S. Food and Drug Administration (FDA) has mandated updated warnings on Pfizer's Comirnaty and Moderna's Spikevax COVID-19 vaccines to include detailed information about the risk of myocarditis and pericarditis, particularly in males aged 12 to 24. The updated labels reflect new data on the 2023-2024 vaccine formulations, estimating about eight cases of myocarditis or pericarditis per 1 million doses administered to individuals aged 6 months through 64 years, with the highest risk in young males. This decision follows a study using cardiac MRI that identified heart muscle changes in patients developing myocarditis post-vaccination, with some showing persistent signs of heart injury months later. The FDA requires manufacturers to include these findings and to investigate potential long-term heart effects. Although the FDA's expanded warnings contrast with earlier CDC conclusions that found no increased myocarditis risk and noted generally mild, quickly resolving cases, the label updates coincide with broader vaccine policy changes under Health Secretary Robert F. Kennedy Jr. The FDA's actions reflect ongoing efforts to balance vaccine safety with public health priorities amid evolving scientific evidence.