FDA opens safety review of injectable RSV drugs approved for babies and toddlers

FDA Reviews Safety of RSV Drugs for Infants Amid Changing Health Policies

Federal health officials have initiated a safety review of two injectable medications designed to protect babies and toddlers from respiratory syncytial virus (RSV), a common respiratory illness that hospitalizes thousands of American children annually.

The Food and Drug Administration is examining drugs manufactured by pharmaceutical giants Merck and Sanofi. Unlike vaccines, these medications are long-acting antibody treatments that provide immediate protection against RSV infection. The review comes at a time when the Department of Health and Human Services, under Secretary Robert F. Kennedy Jr., has been rolling back recommendations for routine childhood vaccinations.

A spokesperson for Secretary Kennedy characterized the inquiry as a standard safety evaluation, stating that the FDA “will update product labeling if warranted by the totality of the evidence.” Both pharmaceutical companies have maintained that no new safety concerns have emerged with their products.

Merck, which manufactures Enflonsia, confirmed that company representatives met with FDA officials last week. “We expect questions from the FDA, and we want them to ask,” the company said in a statement. “We believe deeply in the importance of transparency and we value the FDA’s rigorous review of our clinical data of all of our products.” Enflonsia is approved to protect infants before or during their first RSV season, typically a five-month period.

Similarly, Sanofi defended its product Beyfortus, noting that the company has seen no safety issues across more than 50 studies. “At this time, no safety issue has been identified from clinical studies of Beyfortus or from post-marketing experience with more than 6 million babies immunized worldwide,” Sanofi stated.

RSV presents as a mild cold for most healthy individuals but can become life-threatening for vulnerable populations, particularly infants and the elderly. The virus is a leading cause of hospitalization among young children in the United States, especially during fall and winter months when respiratory illnesses circulate more widely.

In 2023, the Centers for Disease Control and Prevention’s advisory committee recommended these antibody injections for infants born just before or during RSV season if their mothers hadn’t received an RSV vaccine during pregnancy. The panel also advised administering doses to certain high-risk children aged 8 to 19 months who face greater danger from severe RSV illness.

The landscape of public health recommendations has shifted significantly since Kennedy took leadership of HHS. He has replaced every member of the CDC’s advisory committee, which has begun revising longstanding vaccination guidelines. Last week, the newly constituted panel recommended ending routine hepatitis B vaccination for newborns—a decision that prompted immediate criticism from numerous medical and scientific organizations.

The hepatitis B recommendation represents a dramatic departure from decades of public health practice aimed at preventing a virus that can lead to liver failure and cancer. Medical societies have expressed concern that such changes could reverse hard-won progress against preventable diseases.

Meanwhile, FDA officials have been conducting broader examinations of vaccine safety, with particular attention to COVID-19 vaccines. The agency has suggested plans for a comprehensive restructuring of its vaccine approval and review processes, which have been in place for decades.

These developments reflect the changing approach to public health under the current administration, with potential implications for childhood immunization programs that have traditionally enjoyed broad support across the medical community. The outcome of the RSV medication review could influence protection strategies against a virus that remains a significant threat to infant health nationwide.