FDA Approves Enflonsia to Prevent RSV in Infants with One Dose

Merck reported that the USFDA had approved enflosina (clesrovimab-cfor) to prevent respiratory syncytial virus (RSV)-induced lower respiratory tract illness in newborns and babies beginning their first RSV season. Enflosina is a long-acting monoclonal antibody that provides direct protection for up to five months, which is the typical length of an RSV season. All infants, regardless of weight, get a single fixed 105 mg dosage of this antibody.

Key Insights:
• FDA approves Enflonsia to prevent RSV illness in newborns and infants
• Single fixed-dose eliminates weight-based dosing, simplifying infant RSV protection
• U.S. distribution expected by July, ahead of 2025âÂ?Â?2026 RSV season

“RSV is the leading cause of infant hospitalizations in the U.S.,” said Dr. Octavio Ramilo, Chair of Infectious Diseases at St. Jude Children’s Research Hospital and investigator in the CLEVER and SMART trials. “ENFLONSIA’s efficacy and fixed-dose convenience make it a promising preventive option.”

“ENFLONSIA offers a meaningful new option to protect infants, both healthy and at-risk, with a simple dosing regimen,” said Dr. Dean Y. Li, President, Merck Research Laboratories. “We aim to make it available in the U.S. before the upcoming RSV season.”

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The Advisory Committee on Immunization Practices at the CDC is expected to assess ENFLONSIA later this month. In July, distribution is expected to begin, ahead of the RSV season in 2025–2026. Enflonsia has the advantage of being the first and only pediatric RSV preventative medication that does not call for weight-based dosing, making administration simpler and more convenient. Enflonsia and Beyfortus both have excellent safety and effectiveness profiles.