DRUGDOCS | Enflonsia®

Drug updated on 2/4/2026

Dosage Form	Injection (intramuscular; 105 mg/0.7 mL)
Drug Class	human immunoglobulin G1 kappa monoclonal antibody
Ongoing and Completed Studies	ClinicalTrials.gov

Indication

Indicated for the prevention of RSV lower respiratory tract disease in neonates and infants who are born during or entering their first RSV season.

This summary is based on the review of one systematic review/meta-analysis. ^[1]
Enflonsia (clesrovimab-cfor) is indicated for the prevention of respiratory syncytial virus (RSV) lower respiratory tract disease in neonates and infants during their first RSV season.
Clesrovimab (Enflonsia) is noted for its considerable promise relative to other monoclonal antibodies, including motavizumab, motavizumab-YTE, ALX-0171, and suptavumab.
Safety data were reported from 59 studies covering monoclonal antibodies and antiviral therapies; however, specific safety outcomes for clesrovimab (Enflonsia) were not detailed in the study.
No significant safety concerns or adverse effects were specified for clesrovimab (Enflonsia) or other therapies.
Infant populations are identified as a specific subgroup for nirsevimab, which is approved for clinical use in this group; no specific subgroups or clinically relevant population differences are reported for clesrovimab (Enflonsia).

Document Title	Year	Source
Enflonsia (clesrovimab-cfor) Prescribing Information	2025	Merck Sharp & Dohme LLC, Rahway, NJ

Document Title	Year	Source
Systematic Review of the Efficacy and Safety of RSV-Specific Monoclonal Antibodies and Antivirals in Development	2024	Reviews in Medical Virology

Document Title	Year	Source
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.	2025	MWR Morbidity and Mortality Weekly Report