FDA Approves New RSV Antibody,Enflonsia,for Infant Protection

The Food and Drug Administration (FDA) approved Merck‘s Enflonsia (clesrovimab) on Monday, a new monoclonal antibody aimed at protecting infants under 12 months from respiratory syncytial virus (RSV). This approval introduces a third option to combat RSV, a common and perhaps severe respiratory illness in young children. Public health experts anticipate that increased competition may eventually lower the cost of these preventative treatments, easing the financial strain on families and the healthcare system.

Enflonsia vs. Beyfortus: Key Differences

Enflonsia enters the market at a wholesale price of $556 per dose, matching the price of its primary competitor, Beyfortus (nirsevimab), developed by Sanofi and AstraZeneca.While the pricing is identical, the two products differ in dosage and approved use cases.

Did You Know?

RSV is the most common cause of bronchiolitis (inflammation of the small airways in the lung) and pneumonia in children younger than 1 year in the United States. Most children have been infected with RSV by the time they are 2 years old, according to the Centers for Disease Control and Prevention (CDC).

A key advantage of Enflonsia is its single-dose regimen for all infants, nonetheless of weight, potentially simplifying administration in pediatric offices. Beyfortus, on the other hand, requires different dosages based on an infant’s weight. however, Enflonsia is currently approved only for infants in their first RSV season, while beyfortus is approved for all babies in their first RSV season and for high-risk babies in their second season.

Merck’s Strategy and Future Expansion

Paula Annunziato, Merck’s senior vice president for clinical research, highlighted the logistical simplicity of Enflonsia’s single-dose approach. Merck is also conducting a study comparing Enflonsia to Synagis, an older RSV monoclonal antibody approved only for high-risk infants. Positive results could lead to an expansion of Enflonsia’s approval to include high-risk children in their second RSV season.

Impact on RSV Prevention

Clinical trials have demonstrated that Enflonsia reduces medically attended lower respiratory tract infections caused by RSV by over 60% and lowers RSV-related hospitalization rates by over 84%.These figures underscore the potential of Enflonsia to considerably reduce the burden of RSV on infants and the healthcare system.

the introduction of Enflonsia follows the recent availability of other RSV prevention tools, including Pfizer‘s Abrysvo, a vaccine for pregnant individuals that transfers protective antibodies to the fetus. This vaccine is recommended for pregnant individuals between September and January to protect newborns during RSV season.

Timeline for Enflonsia Availability

Merck anticipates beginning to take orders for Enflonsia in July and shipping doses in time for the 2025 RSV season. The availability of multiple preventative options marks a significant advancement in the fight against RSV, offering diverse strategies to protect vulnerable infants.

The Advisory Committee on Immunization Practices (ACIP) was scheduled to vote on recommending Enflonsia at its next meeting in late June. However, recent events, including the replacement of the entire committee, have raised questions about the meeting’s functionality. The Department of Health and Human Services has stated that the meeting will proceed as planned.

Disclaimer: This article provides information about a new medical product. Consult with a healthcare professional for personalized medical advice.

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