FDA approval adds an antibody option for infants’ first RSV season
Enflonsia’s June 2025 approval followed trials evaluating prevention of lower respiratory tract disease.
News report
The U.S. Food and Drug Administration approved Enflonsia, or clesrovimab, on June 9, 2025, to help prevent respiratory syncytial virus lower respiratory tract disease in infants born during or entering their first RSV season.
The medicine is a monoclonal antibody, which supplies a targeted immune protein directly. That distinguishes it from a vaccine designed to stimulate a person’s own immune response. The approval concerns prevention of a defined type of RSV disease, rather than treatment of an existing infection.
FDA’s trial summary describes evidence from two clinical studies. One was a randomized, double-blind, placebo-controlled study conducted at sites in 22 countries and included infants born at different gestational ages. The second study provided additional evidence relevant to safety and the populations considered in the review.
The prescribing information identifies allergic reactions as a possible risk and describes other reported adverse reactions. An approval reflects the regulator’s assessment of benefits and risks for the stated use; it does not mean a medicine is free of adverse effects or appropriate for every infant.
The 2025 decision added another prevention product to the clinical landscape. Individual use involves age, season and health circumstances assessed in routine care, beyond what a news report can determine. The public health significance is the expansion of tools evaluated specifically for the youngest patients, with evidence and eligibility set out in the regulatory record.
