The US Food and Drug Administration (FDA) has ordered Pfizer and Moderna to update their warning labels on COVID-19 vaccines to include a rare risk of heart inflammation in teen boys and young men.
The updated warnings apply to males aged 16-25, based on new data from FDA safety monitoring and a 2023 study. According to the FDA, for every million doses in this age group, there were 38 cases of myocarditis and/or pericarditis. The rate was about 8 cases per million doses for all people under 65.
The Centers for Disease Control and Prevention (CDC) says most of these cases occur soon after vaccination and tend to improve quickly. However, the FDA has noted that it is unclear if heart MRI scans in affected individuals can predict long-term heart effects of myocarditis.
Both Pfizer and Moderna have 30 days to respond to the FDA’s letter. The agencies are seeking transparency around the safety and efficacy of COVID-19 vaccines, with an emphasis on informing individuals about vaccine-related adverse events resulting in myocarditis and pericarditis.
The move comes as the US Senate holds a hearing on “how health officials downplayed and hid” these adverse events associated with COVID-19 vaccines.
Source: https://www.usnews.com/news/health-news/articles/2025-05-22/fda-warns-of-heart-risk-with-pfizer-moderna-covid-vaccines