The U.S. Food and Drug Administration (FDA) is reportedly considering adding a black box warning to COVID-19 vaccines, according to information shared with CNN by two unnamed sources. A black box warning is the FDA’s most serious alert for prescription drugs or medical devices, indicating significant risks that must be weighed against the benefits of treatment.
It remains uncertain whether the potential warning would apply to all COVID-19 vaccines or specifically to mRNA-based products, such as Pfizer/BioNTech’s Comirnaty and Moderna’s Spikevax. Novavax’s protein-based vaccine Nuvaxovid is also approved in the United States. The scope of age groups affected by any new warnings has not been clarified.
The possible move comes amid increased scrutiny of mRNA vaccines since Health Secretary Robert F. Kennedy Jr. assumed office in February and as political debate around pandemic measures continues.
A spokesperson for the Department of Health and Human Services, Andrew Nixon, addressed speculation about FDA plans: “Unless the FDA announces it, any claim about what it will do is pure speculation.” Nixon reiterated this stance in an email to BioSpace on Friday morning, stating, “The FDA takes very seriously any death that is attributed to a regulated medical product.”
According to one source cited by CNN, Vinay Prasad, head of the Center for Biologics Evaluation and Research at the FDA, is leading the initiative for a black box warning. This follows an internal memo from Prasad last month suggesting that 10 child deaths could be linked to COVID-19 vaccination—a claim initially raised by Tracy Beth Høeg while serving as senior advisor at the agency.
This memo has sparked strong opposition from healthcare professionals and former regulatory officials. More than a dozen former leaders from both the FDA and CDC criticized proposed policy changes regarding vaccine safety in an editorial published earlier this month in The New England Journal of Medicine.
Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia, commented on these developments: “I think it’s irresponsible and unprofessional,” he told BioSpace regarding reports about a possible black box warning. He added that neither Vinay Prasad nor FDA Commissioner Marty Makary have provided clear evidence linking COVID-19 vaccines to child fatalities: “because this agency, either Vinay Prasad or [FDA Commissioner] Marty Makary, have not in any way made clear why it is they think the COVID-19 vaccine killed children.”
In response to questions from Endpoints News on December 3rd, an FDA spokesperson said investigations into additional adverse event cases are ongoing and promised a public report on reported deaths by year-end.
Offit expressed interest in seeing detailed autopsy data: he said he would like confirmation of severe heart muscle damage along with antibodies specific to SARS-CoV-2 spike protein—evidence distinguishing vaccination from natural infection.
The FDA has expanded its investigation into deaths potentially related to COVID-19 vaccination across multiple age groups.
Meanwhile, new data released Thursday by the Centers for Disease Control and Prevention (CDC) indicate that updated 2024–2025 formulations of COVID-19 vaccines were 76% effective at preventing emergency or urgent care visits among children aged nine months through four years.
