In a move that has sparked debate among health officials and parents alike, the U.S. Food and Drug Administration has opened a safety review of two approved respiratory syncytial virus (RSV) monoclonal antibody drugs for infants.
FDA Safety Review Launch
The review was announced by the FDA after a Reuters report, and the agency has confirmed that no safety issues have been reported with either drug. Andrew Nixon, a spokesperson at the Department of Health and Human Services, said in an emailed statement that the FDA is “rigorously reviewing the available data, as it does for all products, to ensure decisions remain rooted in evidence-based science and in the best interest of patients.” He added, “FDA routinely evaluates emerging safety information and will update product labeling if warranted by the totality of the evidence.”
No Safety Issues Reported
A Sanofi spokesperson explained that the safety and effectiveness of Beyfortus, a monoclonal antibody drug, has been demonstrated in over 50 clinical studies and real‑world studies, involving more than 400,000 infants. “At this time, no safety issue has been identified from clinical studies of nirsevimab or from post‑marketing experience with more than six million babies immunized worldwide,” the spokesperson said, using the generic name of the drug.
Merck’s spokesperson echoed the same sentiment, noting that the bar for establishing the safety of vaccines and preventive therapies like Enflonsia “is exceptionally, and appropriately, high.” The spokesperson said, “We met briefly with FDA representatives last week and we welcome ongoing scientific exchange and dialogue with the FDA and other regulatory or health authorities, their advisory committees, and scientific leaders on ENFLONSIA, including its safety profile.”
How the Drugs Work and CDC Recommendations
Both Beyfortus and Enflonsia are monoclonal antibodies that function similarly to vaccines, but instead of prompting the immune system to make antibodies, they deliver antibodies directly into the body in a process known as passive immunization. The Centers for Disease Control and Prevention (CDC) recommends either product for infants under 8 months born during or entering their first RSV season. For older infants who are at increased risk, only Beyfortus is recommended. Both drugs are included in the CDC’s childhood immunization schedule.
It remains unclear whether the FDA will change the products’ labels or restrict their availability.
Expert Voices and Public Concerns
Dr. Sean O’Leary, a pediatric infectious disease expert and spokesman for the American Academy of Pediatrics, said he believes the review is meant to “sow distrust” in immunizations. He added, “I certainly hope nothing regulatory comes of this, because there’s no basis for it.” He continued, “But even if it doesn’t, this systematic attempt to dismantle our immunization infrastructure is causing real harm in real time, in creating confusion among parents and even among clinicians.”
O’Leary warned that rolling back access to RSV injections would “inevitably lead to fewer children receiving the monoclonal antibody and more kids getting hospitalized.” He also stated, “These products have been shown to be very safe in clinical trials.” He noted, “Now that they’ve been put into broad use, we’re seeing really profound impacts on hospitalizations for young children.”
Context: Vaccine Policy Moves
On Friday, a CDC vaccine advisory group handpicked by Health Secretary Robert F. Kennedy Jr. voted to rollback a decades‑long recommendation that all newborns receive a dose of the hepatitis B vaccine within 24 hours of birth. Major medical organizations decried the move. The same uncertainty surrounding RSV therapies echoes the broader debate over vaccine policy and public confidence.
RSV Impact and Prevention
People infected with RSV typically show symptoms 4‑6 days after infection. Roughly two to three of every 100 infants under 6 months are hospitalized with RSV every year, according to the CDC. Most cases cause mild, cold‑like symptoms, but RSV can also lead to severe illness, including pneumonia and bronchiolitis, a lung infection that makes breathing difficult. Cases of RSV are beginning to increase in parts of the U.S., per CDC data.
The CDC recommends basic preventative measures such as washing hands and avoiding close contact with others to reduce the risk of RSV transmission.
Key Takeaways
- FDA has launched a safety review of Beyfortus and Enflonsia, but no safety issues have been identified to date.
- Sanofi and Merck affirm the safety record of their products, citing extensive clinical and real‑world data.
- The review has sparked criticism from pediatric experts who warn that it could erode public confidence in essential infant immunizations.
The FDA’s review underscores the ongoing scrutiny of new preventive therapies and highlights the delicate balance between regulatory oversight and maintaining public trust in life‑saving medical interventions.
