Merck’s RSV treatment for infants is approved by FDA

A recent milestone in the fight against respiratory syncytial virus (RSV) was achieved with the approval of Merck’s clesrovimab by the Food and Drug Administration. Marketed under the name Enflonsia, this monoclonal antibody product is designed to protect children under the age of 12 months from the severe effects of RSV infection. Priced at $556 per dose, Enflonsia is set to compete with Sanofi and AstraZeneca’s Beyfortus (nirsevimab) at the same price point.

One key advantage of Enflonsia is its single dosage for all babies, regardless of weight, simplifying the administration process for healthcare providers. This streamlined approach aims to address logistical challenges faced during the rollout of other RSV treatments. However, while Beyfortus is approved for use in both the first and second RSV seasons for high-risk babies, Enflonsia is currently only approved for infants in their first year facing the virus.

Merck is actively conducting a study comparing Enflonsia to Synagis, the first RSV monoclonal antibody on the market, with hopes of expanding its license to include high-risk children in their second RSV season. The Advisory Committee on Immunization Practices was expected to evaluate Enflonsia at its upcoming meeting, but recent developments, including the dismissal of the entire committee, have raised concerns about the meeting’s proceedings.

Despite these challenges, Merck plans to begin accepting orders for Enflonsia in July, aiming to ship doses in time for the 2025 RSV season. The efficacy of Enflonsia in reducing medically attended lower respiratory infections and RSV hospitalizations by significant margins underscores its potential impact on infant health and healthcare systems.

In recent years, the landscape of RSV prevention has evolved with the introduction of Pfizer’s Abrysvo vaccine for pregnant individuals, offering maternal antibodies to protect newborns. For babies born to unvaccinated mothers, monoclonal antibody treatments like Enflonsia provide a vital defense against RSV, ensuring protection during the vulnerable fall and winter seasons.

The approval of Enflonsia marks a significant step forward in the battle against RSV, offering hope for families and healthcare providers alike. As new preventive tools continue to emerge, the fight against RSV is gaining momentum, bringing us closer to a world where infants are safeguarded against this debilitating virus.