Date: June 9, 2025
Company: Merck
Brand: Enflonsia
Generic: clesrovimab-cfor
Indication: Passive immunization for the prevention of respiratory syncytial virus (RSV) lower respiratory tract disease in newborns and infants who are born during or entering their first RSV season.
On June 9, 2025, the U.S. Food and Drug Administration (FDA) approved Merck’s RSV preventive option, Enflonsia (clesrovimab-cfor), for the prevention of respiratory syncytial virus (RSV) lower respiratory tract disease in infants.
The long-acting monoclonal antibody (mAb) provides rapid, direct, and durable protection for the first five months of a baby’s life. Enflonsia is administered in a 105 mg dose, making it the first and only RSV preventive option for infants that uses the same dose regardless of weight.
The first dose should be administered to an infant during or preceding their first, active RSV season. Infants with a history of serious hypersensitivity reactions, including anaphylaxis, should not receive Enflonsia. The most common adverse reactions noted were injection-site erythema (3.8%), injection-site swelling (2.7%), and rash (2.3%).
RSV is a notable concern for parents with newborns. The Centers for Disease Control and Prevention estimates that 58,000 to 80,000 children younger than five years old are hospitalized due to RSV every year, noting that the younger the child the higher their risk of severe illness from RSV.
Guidelines Related To This Topic:
- The Management of Community-Acquired Pneumonia in Infants and Children Older Than 3 Months of Age
- Infectious Diseases Society of America/Pediatric Infectious Diseases Society
- Chronic Cough Related to Acute Viral Bronchiolitis in Children
- American College of Chest Physicians
- Post-Prematurity Respiratory Disease
- American Thoracic Society
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