The US FDA is reviewing a request from Merck to extend the use of Enflonsia, potentially extending protection for children under 2 after their first respiratory syncytial virus (RSV) season, amid growing concerns over repeat infections.
The US Food and Drug Administration has accepted Merck’s request to expand the label for Enflonsia, a move that could broaden protection against respiratory syncytial virus for children under 2 who remain at risk after their first RSV season.
The application seeks approval for use in children under 2 who are vulnerable to severe RSV lower respiratory tract disease during a second season, including those with chronic lung disease, congenital heart disease or certain pre-term birth risk factors. Merck says Enflonsia is the first and only preventive option against RSV lower respiratory tract disease that can be given to infants without weight-based dosing.
RSV is a highly contagious virus that infects the lungs and breathing passages and can be especially dangerous for infants. The FDA already lists several preventive options for babies, including monoclonal antibodies such as nirsevimab and palivizumab, but Merck argues Enflonsia would fill a particular gap for children who need continued protection beyond their first RSV season.
The filing is backed by phase 3 SMART trial data, which Merck says have already been presented at a Respiratory Syncytial Virus Foundation conference and published in the New England Journal of Medicine and JAMA Pediatrics. The European Medicines Agency accepted a similar expansion request in July, and Merck said the FDA has set a target decision date of March 22, 2027. Enflonsia is already approved in more than 40 countries for infants during their first RSV season, after earlier clearances in the US and European Union.
Disclaimer: This content is for informational purposes only and is not intended to be a substitute for professional medical judgment, advice, diagnosis, or treatment.
