The US Food and Drug Administration (FDA) has instructed Pfizer/BioNTech and Moderna to add clearer warnings about rare heart inflammation risks on their Covid-19 vaccine labels. This update aims to provide more detailed information about myocarditis and pericarditis, especially for specific age groups at higher risk.
The updated labels will highlight the rare possibility of myocarditis—heart muscle inflammation—and pericarditis—inflammation of the heart’s outer lining—following vaccination. The US Centers for Disease Control and Prevention (CDC) confirms these cases are uncommon but may occur, mainly among younger males.
Despite these warnings, extensive studies continue to show that mRNA Covid-19 vaccines are safe and effective for most people. Millions have been vaccinated without serious side effects. Data indicates that catching Covid-19 itself carries a higher risk of developing myocarditis or pericarditis than receiving the vaccine.
The CDC recently shared data from 2020 to 2022 showing a slight but statistically significant increase in myocarditis cases following vaccination. However, cases remain rare and there has been no evidence of increased risk with vaccine doses given after 2022. When myocarditis occurs post-vaccination, it generally resolves quickly without lasting health problems, according to the CDC.
The new warnings focus on males aged 16 to 25, expanding from the previous age groups of 18 to 24 for Moderna and 12 to 17 for Pfizer. FDA letters dated April 17 revealed insurance claim analyses that recorded about eight myocarditis or pericarditis cases per million doses in people aged six months to 64 years. Among males 16 to 25, cases were slightly more frequent within seven days after vaccination, at approximately 38 per million doses, but still rare.
A spokesperson for the Department of Health and Human Services said the label updates promote “radical transparency.” Pfizer and Moderna have not made public comments on these changes.
These vaccines were developed during the Trump administration and underwent what the CDC describes as “the most intensive safety analysis in US history.” Monitoring of vaccine safety and effectiveness continues, even amid ongoing political debates.
Health and Human Services Secretary Robert F. Kennedy Jr., a known vaccine skeptic, has falsely called the Covid-19 vaccines “the deadliest vaccine ever made.” Meanwhile, Senator Ron Johnson accused the Biden administration of minimizing vaccine risks and delaying safety information during a Senate hearing.
In contrast, Hawaii Governor Josh Green, a family physician, praised the vaccine safety monitoring process. He said it functioned “exactly as intended” by identifying rare myocarditis cases and delivering timely data updates and clinical guidance. He also criticized misinformation suggesting the vaccines are broadly unsafe.
Recently, the FDA narrowed eligibility for updated Covid-19 vaccines expected this fall. The revised guidance prioritizes adults 65 and older and those with certain health conditions. FDA officials Dr. Marty Makary and Dr. Vinay Prasad called for more placebo-controlled studies, especially among adults aged 50 to 64, before recommending routine boosters for healthy children and adults.
The FDA’s vaccine advisory panel is scheduled to meet soon to choose coronavirus strains for the next seasonal vaccines.