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Getting the latest healthcare news for you
Getting the latest healthcare news for you
The FDA is now reviewing whether clesrovimab (Enflonsia) should be approved to protect high-risk children through their second RSV season. Phase 3 SMART trial data show the drug was well-tolerated, with RSV-related illness rates comparable to the older standard, palivizumab. A decision is expected by March 22, 2027.
The FDA has accepted Merck's application to expand approval of clesrovimab (Enflonsia) — a long-acting monoclonal antibody — to cover high-risk children under 2 years old entering their second RSV season. Currently, clesrovimab is only approved for infants in their first RSV season. The expansion targets kids with conditions like prematurity, chronic lung disease, or congenital heart disease, who remain vulnerable beyond year one.
The application is backed by phase 3 SMART trial data involving 997 high-risk infants. In season one, a single 105 mg dose of clesrovimab performed comparably to monthly palivizumab doses — with similar RSV-associated illness and adverse event rates. For season two, 276 eligible children received a higher 210 mg dose, which was also well-tolerated, with no treatment-related serious adverse events.
By the Numbers:
Why it matters: RSV is a leading cause of infant hospitalization worldwide, and high-risk children don't always age out of danger after year one. If approved, clesrovimab's fixed single dose — simpler than weight-based or monthly alternatives — could make second-season RSV prevention more accessible and easier to administer.
