WASHINGTON — The Food and Drug Administration (FDA) announced updates to warnings about possible heart inflammation, a rare side effect primarily observed in young male recipients of the leading COVID-19 vaccines. The side effect, known as myocarditis, surfaced as a potential complication when the vaccines became widely accessible in 2021. Prescribing guidelines for both Pfizer and Moderna vaccines already highlighted this issue, but the FDA recently instructed the manufacturers to refine and broaden their warnings. This initiative aims to offer a more comprehensive account of the condition and extend coverage to a larger demographic.
In April, the FDA issued letters to Pfizer and Moderna requesting they revise the labels on their COVID-19 vaccines. While the FDA possesses the authority to enforce label changes, these modifications are typically a collaborative effort with the companies involved. The updated warning identifies the myocarditis risk at 8 cases per 1 million vaccinations for individuals aged 6 months to 64 years, particularly noting its prevalence among young men aged 12 to 24. Prior warnings mainly cited occurrences in 12- to 17-year-olds.
This alteration in labeling contrasts with previous assessments from other U.S. governmental scientists. For instance, the Centers for Disease Control and Prevention (CDC) previously reported no increased myocarditis risk based on government vaccine injury data from as far back as 2022. Additionally, they pointed out that post-vaccine heart inflammation cases generally resolve swiftly and are typically milder than COVID-19-induced myocarditis.
The FDA’s recent label update was issued amid discussions by new vaccine advisers, appointed by Health Secretary Robert F. Kennedy Jr., on the ongoing use of COVID-19 vaccines for critical groups, including pregnant women. This is the inaugural meeting of the CDC advisory panel since Kennedy’s abrupt replacement of all 17 members with new appointees, some of whom have criticized vaccines in the past.
The FDA’s approach to labeling changes fits within broader efforts led by officials under Kennedy to challenge vaccine usage. FDA Commissioner Marty Makary, along with a senior deputy, recently recommended limiting annual COVID-19 vaccinations to seniors and those at enhanced risk. They suggested that seasonal adjustments to vaccines, if necessary, would warrant additional scrutiny and approval.
Experts outside the FDA criticized the new warning as misguided. Dr. Robert Morris, a public health authority from the University of Washington, remarked, “While it’s crucial to recognize myocarditis risks, the proposed solution is incorrect. Instead, we should focus on identifying individuals more susceptible to myocarditis and find strategies to mitigate that risk.”
Makary and some colleagues at the FDA gained recognition during the pandemic for their critical stance on government policies regarding COVID-19 boosters. Before his tenure at the FDA, Makary, along with two deputies, co-authored a paper in 2022 contending that booster mandates for young adults might lead to more vaccine-related injuries than the COVID-19 hospitalizations they prevent. This view stood in opposition to many public health authorities and experts at the CDC at that time.