FDA Approves Merck RSV⁤ Shot, ⁢Enflonsia, for Infant Protection

⁤ ​ ⁢ Updated june 10, 2025
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The Food and⁢ Drug Administration has approved Merck’s Enflonsia (clesrovimab-cfor), an RSV shot designed to protect infants​ from respiratory syncytial virus. This approval positions Merck to compete with Sanofi and AstraZeneca’s Beyfortus in the ⁣ infant RSV prevention market.

Merck anticipates that orders‍ for Enflonsia will begin in july, with shipments preceding the typical fall and‍ winter RSV season. The RSV treatment offers doctors another option to combat the virus, a leading cause ‍of infant hospitalizations and a contributor to⁣ thousands of deaths among older adults ⁣annually.

Dr. Dean Li,president of Merck ‌Research‌ laboratories,stated the company’s commitment to ensuring Enflonsia’s availability‍ before the ⁢upcoming‍ RSV season. The goal is to alleviate ‍the ​burden ⁤of this ⁢widespread seasonal infection on ⁢families and healthcare​ systems, Li said.

Enflonsia and Beyfortus are both preventative monoclonal antibodies, delivering immediate protection by directly introducing ⁣antibodies into the ⁣bloodstream. Though,‌ they target different parts of the virus, making ⁣direct comparisons challenging. A key differentiator is that Enflonsia’s ⁢dosage is ⁢not weight-based, possibly⁣ offering dosing convenience.

We are committed to ensuring availability of [Enflonsia] in the U.S. before the‌ start of the upcoming RSV season to help reduce the critically‌ important burden of this widespread seasonal infection on families and health care systems.

Sanofi announced‌ plans to⁢ increase Beyfortus supply, aiming to begin ⁣shipments early in the third quarter. Beyfortus generated €1.7 billion ⁢($1.8 billion) in sales last year.

What’s next

The ​CDC’s outside vaccine advisors will⁢ convene from June 25-27 to formulate recommendations for RSV shots​ and other immunizations, shaping⁤ the⁣ future landscape of RSV prevention and ‍treatment.