On June 26, 2025, the CDC's Advisory Committee on Immunization Practices (ACIP) voted to recommend Merck's Enflonsia (clesrovimab-cfor) for the prevention of RSV lower respiratory tract disease in infants under 8 months old entering their first RSV season1234.
Enflonsia is a long-acting monoclonal antibody, not a vaccine, and is the first RSV preventative for infants to use a single dose regardless of weight12.
Enflonsia was FDA-approved in early June 2025 and is now the second monoclonal antibody option for RSV, joining Sanofi/AstraZeneca's Beyfortus24.
Clinical data showed Enflonsia cut medically attended RSV lower respiratory infections by over 60% and reduced RSV hospitalizations by more than 84%2.
The ACIP vote was 5 to 2 in favor of recommending Enflonsia for infants not already protected by a maternal RSV vaccine34.
ACIP also voted to include Enflonsia in the Vaccines for Children (VFC) program, expanding free access for eligible families14.
Merck plans to make Enflonsia available for ordering in July 2025, with shipments to be delivered ahead of the 2025–2026 RSV season12.
Sources:
1. https://www.merck.com/news/acip-recommends-use-of-mercks-enflonsia-clesrovimab-cfor-for-prevention-of-respiratory-syncytial-virus-rsv-lower-respiratory-tract-disease-in-infants-younger-than-8-months-of-age/
2. https://www.statnews.com/2025/06/26/cdc-acip-merck-rsv-monoclonal-antibody-enflonsia/
3. https://www.fiercepharma.com/pharma/cdc-advisory-panel-endorses-mercks-rsv-shot-enflonsia-not-without-dissent
4. https://www.contagionlive.com/view/acip-recommends-clesrovimab-for-infants-under-8-months-without-maternal-rsv-protection