Merck gains EU backing for 24-month RSV use

Merck (NYSE:MRK) received a positive recommendation from the European Medicines Agency's Committee for Medicinal Products for Human Use (CHMP) to expand ENFLONSIA's indication to prevent respiratory syncytial virus (RSV) lower respiratory tract disease in eligible high-risk children up to 24 months old.

The recommendation expands ENFLONSIA's potential use beyond the first RSV season, following its European Commission approval in April 2026 for preventing RSV lower respiratory tract disease in infants during their first season.

"For some children, the risk of severe RSV does not end after their first RSV season and they remain at increased risk for serious cases of RSV-related bronchiolitis or pneumonia that can require hospitalization," said Dr. Macaya Douoguih, Vice President and Therapeutic Area Head of Global Clinical Development at Merck Research Laboratories.

The Phase 3 SMART trial supporting the recommendation included 276 eligible children receiving an additional 210 mg ENFLONSIA dose during their second RSV season, with 99% of recipients having chronic lung disease or congenital heart disease.

The European Commission will review the CHMP recommendation and is expected to issue its final marketing authorization decision within two months, while the U.S. FDA has set March 22, 2027, as its target decision date for a similar expanded indication.

ENFLONSIA, whose active ingredient is clesrovimab, was first approved in the United States in June 2025 and Europe in April 2026, and Merck says the medicine is now approved in more than 55 countries for first-season RSV prevention.