New Monoclonal Antibody for RSV Prevention in Infants Gains FDA Approval

A recently approved medical breakthrough promises enhanced protection for infants against respiratory syncytial virus (RSV), which is a leading cause of hospitalization in young children across the United States. The U.S. Food and Drug Administration (FDA) has authorized the use of Enflonsia, a monoclonal antibody developed by Merck, designed to safeguard newborns and infants throughout their initial RSV season, typically from fall to early spring.

Administered as a single 105-milligram injection, Enflonsia demonstrated remarkable efficacy in clinical trials, reducing RSV-related hospitalizations by over 84%. It also significantly lowered the incidence of severe lower respiratory infections such as pneumonia by more than 60%. According to Dr. Dean Li, president of Merck Research Laboratories, Enflonsia offers a crucial new tool for protecting at-risk and healthy infants during the seasonal outbreak.

The safety profile of Enflonsia was comparable to placebo with mild side effects like swelling at the injection site and rash being the most common. The drug is expected to become available in the US before the upcoming RSV season, pending recommendations from the Centers for Disease Control and Prevention (CDC). However, recent delays in CDC review processes—due to administrative changes—may affect the timing.

RSV remains a common virus, with most children experiencing it by age two. While it often causes mild cold-like symptoms in older children and adults, it can be devastating for infants. The virus may inflame tiny airways, complicating breathing and leading to serious conditions like bronchiolitis and pneumonia, sometimes resulting in death. Annually, about 2-3% of infants under six months are hospitalized due to RSV, equating to roughly 58,000 to 80,000 hospitalizations for children under five.

Currently, there’s no specific antiviral treatment for RSV; management typically involves supportive care such as oxygen therapy. Healthcare professionals express deep concern over the ongoing impact of RSV, emphasizing the importance of preventive measures. In addition to Enflonsia, another antibody, Beyfortus by Sanofi and AstraZeneca, was approved in 2023 but faced supply constraints last season. Vaccination strategies during pregnancy also help protect newborns.

Recent studies indicate that these preventive tools are making a difference, with lower hospitalization rates observed during the 2024–2025 season. Experts urge parents to utilize all available preventative options to reduce the burden of RSV on families and healthcare systems.

This advancement marks a significant step forward in pediatric infectious disease prevention, providing hope for a future where severe RSV cases become much less common. For more details, visit source.