A new medication from Merck has been approved by the Food and Drug Administration to shield newborns from respiratory syncytial virus, or RSV, a common but potentially dangerous seasonal infection.

The medication, Enflonsia, is a long-acting monoclonal antibody designed to shield newborns and infants starting their first RSV season from lower respiratory tract illness caused by RSV. According to the Centers for Disease Control and Prevention, RSV is a major reason why infants in the US are admitted to hospitals, particularly in the fall and winter.

According to Merck, enflosina (clesrovimab-cfor) has been approved by the USFDA to prevent lower respiratory tract sickness in newborns and infants starting their first season of respiratory syncytial virus (RSV). A long-acting monoclonal antibody called enflosina offers direct protection for up to five months, which is how long an RSV season usually lasts. This antibody is administered in a single fixed dosage of 105 mg to all newborns, regardless of weight.

Dr. Octavio Ramilo, Chair of Infectious Diseases at St. Jude Children’s Research Hospital and an investigator in the CLEVER and SMART studies, stated that RSV is the primary cause of hospitalizations for infants in the United States. “ENFLONSIA is a promising preventive option due to its effectiveness and fixed-dose convenience.”

“With a straightforward dosage schedule, ENFLONSIA provides a significant new choice to safeguard infants, both healthy and at-risk,” stated Dr. Dean Y. Li, President of Merck Research Laboratories. “Our goal is to release it in the United States prior to the forthcoming RSV season.”

Later this month, the CDC’s Advisory Committee on Immunization Practices is anticipated to evaluate ENFLONSIA. Distribution is anticipated to start in July, in advance of the 2025–2026 RSV season.

Being the first and only pediatric RSV prophylactic drug without weight-based dosing, Enflonsia offers the benefit of being easier and more convenient to administer. Both Beyfortus and Enflonsia have outstanding safety and efficacy records.