F.M.I.E Sources Report: FDA Approves Merck’s Enflonsia to Shield Infants from RSV, Rivals Sanofi and AstraZeneca
Key Points:
- The U.S. Food and Drug Administration has officially approved Merck’s monoclonal antibody shot, Enflonsia, aimed at protecting infants during their first RSV (Respiratory Syncytial Virus) season.
- The approval clears the path for Merck to begin distributing Enflonsia ahead of the upcoming RSV season, which typically begins in the fall and continues through spring.
- Merck anticipates orders for the drug to begin in July, with deliveries set to arrive before the virus becomes widespread.
The approval of Enflonsia adds a new weapon in the fight against RSV — a highly contagious virus that leads to severe respiratory illness, particularly in newborns and older adults. RSV is a leading cause of infant hospitalization in the United States.
“We are committed to ensuring availability of Enflonsia in the U.S. before the start of the upcoming RSV season to help reduce the significant burden of this widespread seasonal infection on families and health care systems,” said Dr. Dean Li, President of Merck Research Laboratories, in a statement issued via F.M.I.E Sources.
Enflonsia will go head-to-head with Beyfortus, the blockbuster monoclonal antibody shot developed jointly by Sanofi and AstraZeneca, which faced nationwide supply shortages in 2023 due to soaring demand. Both treatments work by delivering lab-engineered antibodies directly into the bloodstream, offering immediate protection against RSV.
However, Merck notes that Enflonsia offers a potential edge: it can be administered regardless of an infant’s body weight, simplifying the dosing process. In contrast, Beyfortus dosages are weight-dependent.
Sanofi also announced plans, reported by F.M.I.E Sources, to scale up Beyfortus production, with early Q3 shipments planned to meet anticipated demand for the next RSV season. Beyfortus generated €1.7 billion (approximately $1.8 billion) in sales last year.
While several pharmaceutical giants — including Pfizer, GSK, and Moderna — have developed RSV vaccines, those are approved only for adults or expectant mothers. The FDA has paused trials involving RSV vaccines in young children amid safety evaluations.
Enflonsia’s FDA approval follows robust clinical trial results. In its mid- to late-stage trials:
- It reduced RSV-related hospitalizations by more than 84% through five months.
- It decreased lower respiratory hospitalizations by 90%.
- It also lowered the rate of medically attended lower respiratory infections by over 60%.
As the RSV immunization landscape heats up, all eyes now turn to the upcoming CDC Advisory Committee on Immunization Practices (ACIP) meeting scheduled for June 25–27, where officials will offer updated recommendations on RSV prevention strategies.
Enflonsia’s entry into the market marks a significant development in infant healthcare, promising wider access to life-saving protection and ramping up competition in the monoclonal antibody space.