Merck Enflonsia wins ACIP backing for RSV protection in infants under 8 months
Rahway: Merck, known as MSD outside of the United States and Canada, has announced the U.S. Centers for Disease Control and Prevention (CDC) Advisory Committee on Immunization Practices (ACIP) voted to recommend ENFLONSIA (clesrovimab-cfor) as an option for the prevention of respiratory syncytial virus (RSV) lower respiratory tract disease in infants younger than 8 months of age who are born during or entering their first RSV season.
The ACIPalso voted to include ENFLONSIA in the Vaccines for Children Program—an important step in ensuring broad access to this preventive option for infants.
ENFLONSIA is a preventive, long-acting monoclonal antibody (mAb) designed to provide direct, rapid and durable protection through 5 months, a typical RSV season, with the same dose regardless of weight. A typical RSV season usually spans autumn to spring of the next year.
ENFLONSIA should not be administered to infants with a history of serious hypersensitivity reactions, including anaphylaxis, to any component of ENFLONSIA. See additional Selected Safety Information below.
“Ahead of the 2025-2026 RSV season, we are proud to offer ENFLONSIA as a new preventive option designed to protect healthy and at-risk infants from RSV disease across a spectrum of severity, including worsening disease requiring hospitalization,” said Dr. Richard M. Haupt, vice president, head of global medical & scientific affairs, vaccines and infectious diseases, Merck Research Laboratories. “The Committee’s recommendation is an important step forward in efforts to help reduce the significant burden RSV continues to place on infants, families and health care systems.”
The U.S. Food and Drug Administration (FDA) approved ENFLONSIA earlier this month based on clinical data from the Phase 2b/3 CLEVER and Phase 3 SMART trials. Merck plans to make ENFLONSIA available for ordering by physicians and health care administrators in July 2025, with shipments to be delivered before the start of the 2025-2026 RSV season.
The ACIP’s recommendation for ENFLONSIA is provisional and will be official once reviewed and finalized by the CDC Director or the Health and Human Services Secretary (in the absence of a CDC Director).
ENFLONSIA is administered using the same dose regardless of weight (105 mg/0.7 mL in a prefilled syringe) and is designed to provide direct, rapid and durable protection through 5 months, a typical RSV season. For infants born during the RSV season, ENFLONSIA is to be administered within the first week of life. For infants born outside of the RSV season, ENFLONSIA should be administered shortly before the RSV season begins. For infants undergoing cardiac surgery with cardiopulmonary bypass during or entering their first RSV season, an additional 105 mg dose is recommended as soon as the infant is stable after surgery. ENFLONSIA has a 30-month shelf life.
