The FDA has approved Merck’s RSV antibody injection for newborns and infants, to be marketed under the name Enfanzia. The one-time shot, known scientifically as clesrovimab, is Merck’s direct competitor to Sanofi and AstraZeneca’s RSV shot, Beyfortus — which made $1.8 billion in its first year.\nThe approval positions Merck to claim a share of what analysts project to be a $13.59 billion global RSV market by 2030.\nMerck says Enfanzia will reduce RSV-related hospitalizations by over 84% and medically attended cases by 60%. The company claims its safety profile is comparable to placebo.\nBut clinical trial data tell a different story.\nAccording to records filed on ClinicalTrials.gov, infants who received Enfanzia experienced an 11.71% serious adverse event (SAE) rate — including a range of neurological issues such as seizures, febrile convulsions, facial paralysis, and brain injuries. These events were three times more frequent than in the placebo group.\nThere were also more deaths: three in the Enfanzia group, compared to one in the placebo group — a 50% increase. Additionally, babies who received the shot were more likely to suffer respiratory tract infections. Upper respiratory infections increased by 350%, and lower tract infections rose by 63%.\nDr. Karl Jablonowski, a biostatistician with Children’s Health Defense, questioned the FDA’s standards:\n“If these are the standards for a successful FDA application, what does it take to fail?”\nOne major safety concern is the one-size-fits-all dose. Enfanzia uses a flat 105 mg dose regardless of the infant’s size. Dr. Peter Selley, a retired pediatrician, warned this could lead to dangerously high drug levels in very small or premature babies.\n“Tiny preterm babies under 5 kilograms are going to be injected with a relatively much bigger dose… leading to massive levels of the drug in their circulation.”\nRSV, or respiratory syncytial virus, infects nearly all babies by age two. While it is the leading cause of infant hospitalizations in the U.S., most cases are mild, and infant deaths remain rare — averaging about 25 per year.\nSeveral pharmaceutical companies are now racing to dominate the infant RSV market. Pfizer’s Abrysvo, approved for use in pregnant women, was linked to increased risk of preterm birth. Beyfortus, a two-dose RSV shot, is already on the market. Synagis is reserved for high-risk infants only.\nThe CDC’s Advisory Committee on Immunization Practices (ACIP) is scheduled to vote on whether to recommend Enfanzia at its June 25–27 meeting. But the vote may now be uncertain: RFK Jr., in his role as HHS secretary, recently removed all 17 members of ACIP, citing systemic corruption and ties to the pharmaceutical industry.

FDA approves Merck’s RSV shot for babies despite 11.71% serious adverse reactions

The FDA approved Merck’s RSV antibody injection Enfanzia for newborns and infants, positioning the company to capture a projected $13.59 billion global RSV market by 2030. However, clinical trials revealed higher serious adverse events (SAEs) in the Enfanzia group compared to placebo, including neurological issues, deaths, and increased infection rates. The approval faces uncertainty as the CDC’s ACIP committee may be influenced by recent changes to its leadership.