MSD (MRK.US) infant RSV vaccine approved in US refers to Sanofi/AstraZeneca

Zhitongcaijing · 06/10/2025 13:49

The Zhitong Finance App learned that MSD (MRK.US)'s prophylactic antibody therapy Enflonsia has been approved by the US FDA to protect infants from respiratory syncytial virus (RSV) infection. Currently, this market is dominated by Beyfortus, an RSV vaccine developed by Sanofi (SNY.US) and AstraZeneca (AZN.US).

MSD said in a statement that EnFlonsia will be used in the US to prevent newborns and infants from contracting lower respiratory diseases during their first RSV season.

The company added that this intramuscular injection, also known as clesrovimab-cfor, will be the first RSV prophylaxis injection for children using the same 105 mg dose regardless of the child's body weight.

The US Centers for Disease Control and Prevention (CDC) Immunization Practice Advisory Committee is expected to meet later this month to discuss and make recommendations on how to use this treatment in the US. MSD is expected to receive orders from Enflonsia in July and ship them in time for the 2025/2026 RSV season.

Beyfortus was approved by the FDA in 2023 to prevent RSV infection in infants and young children under 2 years of age. Last year, sales reached 1.7 billion euros (1.8 billion US dollars). Sanofi said on Monday that shipments of the drug will begin in the early third quarter to prepare for the upcoming respiratory virus season.