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Practice Guideline
. 2025 Aug 28;74(32):508-514.
doi: 10.15585/mmwr.mm7432a3.

Use of Clesrovimab for Prevention of Severe Respiratory Syncytial Virus-Associated Lower Respiratory Tract Infections in Infants: Recommendations of the Advisory Committee on Immunization Practices - United States, 2025

Danielle L Moulia, Ruth Link-Gelles, Helen Y Chu, Denise Jamieson, Oliver Brooks, Sarah Meyer, Eric S Weintraub, David K Shay, Mila M Prill, Ebony S Thomas, David Hutton, Ismael R Ortega-Sanchez, Adam MacNeil, Meredith L McMorrow, Jefferson M Jones
Practice Guideline

Use of Clesrovimab for Prevention of Severe Respiratory Syncytial Virus-Associated Lower Respiratory Tract Infections in Infants: Recommendations of the Advisory Committee on Immunization Practices - United States, 2025

Danielle L Moulia et al. MMWR Morb Mortal Wkly Rep. .

Abstract

Before the introduction of universal respiratory syncytial virus (RSV) immunization recommendations for infants, RSV was the leading cause of hospitalization among infants in the United States. Since 2023, CDC's Advisory Committee on Immunization Practices (ACIP) has recommended that all infants be protected against RSV-associated lower respiratory tract infection (LRTI) through either 1) maternal RSV vaccination during pregnancy (Abrysvo, Pfizer) or 2) administration of nirsevimab (Beyfortus, Sanofi and AstraZeneca), a long-acting RSV monoclonal antibody, to the infant. In June 2025, the Food and Drug Administration licensed clesrovimab (Enflonsia, Merck), a second long-acting RSV monoclonal antibody, for prevention of RSV-associated LRTI in infants. Since September 2024, the ACIP Maternal/Pediatric RSV Work Group has reviewed evidence regarding the safety and efficacy of clesrovimab use in infants. On June 26, 2025, ACIP recommended clesrovimab as a second long-acting monoclonal antibody product that could be used as an alternative to nirsevimab for prevention of RSV-associated LRTI among infants aged <8 months who are born during or entering their first RSV season and who are not protected through maternal RSV vaccination. All infants should be protected against RSV-associated LRTI through use of one of these three products (i.e., maternal RSV vaccination or administration of nirsevimab or clesrovimab to the infant). No one product is preferred; the choice should be guided by parent preference, product availability, and timing of the infant's birth relative to the RSV season.

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Conflict of interest statement

All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. Helen Y. Chu reports receipt of grants or contracts from the National Institutes of Health; payment or honoraria from Merck for a 1-day meeting in January 2023 on molnupiravir use as RSV antiviral treatment (an activity that was reviewed by the ACIP secretariat and was determined not to constitute a conflict of interest at the time of the disclosure, which was more than 6 months before work group review of clesrovimab or any Merck products), Medscape (speaker bureau), Clinical Care Options (speaker bureau), Catalyst Medical Education (speaker bureau), Vir Biotechnology (advisory board), U.S. Department of Defense (advisory board), the American Heart Association (lecture honoraria), the University of Minnesota (lecture honoraria), Roche (advisory board), Catholic University, Seoul, South Korea (lecture honoraria), Washington University in St. Louis (lecture honoraria), and the American Academy of Allergy, Asthma & Immunology (AAAAI) meeting (lecture honoraria); and travel or meeting support from Medscape (respiratory syncytial virus continuing medical education [RSV CME]), Prime (RSV CME), Infectious Diseases Society of America (annual meeting), International Symposium on Antimicrobial Agents and Resistance, Washington University Virology Symposium, Pediatric Academic Society, and AAAAI meeting; and service on CDC’s Advisory Committee on Immunization Practices. No other potential conflicts of interest were disclosed.

References

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