In a letter to the drugmaker, the FDA said the agency approved Beyfortus, an RSV monoclonal antibody, as a defense against RSV lower respiratory tract disease — but that Sanofi has been claiming it protects broadly against RSV disease, which occurs in the lower and upper tracts. Beyfortus has come under scrutiny following reports of at least two infant deaths during clinical trials for the drug.
The U.S. Food and Drug Administration (FDA) is accusing Sanofi of making false or misleading promotional claims about Beyfortus, a preventative treatment for RSV, Fierce Pharma reported.
In a letter to the drugmaker, the FDA said it approved Beyfortus specifically as a defense against respiratory syncytial virus (RSV) lower respiratory tract disease — but that Sanofi has been claiming it protects broadly against RSV disease, which occurs in the lower and upper tracts.
The company has sent providers emails urging them to give the shot to “help prevent RSV disease in infants.”
The promotional materials included other similar statements, including, “Beyfortus is a monoclonal antibody that helps prevent RSV disease starting from Day 1 after injection,” and “Your efforts in immunizing infants against RSV disease can impact the population health burden in your community.”
The FDA said that language creates the “misleading impression” that the drug prevents RSV disease generally.
FDA asks Sanofi to take immediate action to stop misbranding RSV shot
Beyfortus, a monoclonal antibody manufactured by Sanofi and AstraZeneca, was approved by the FDA in 2023. Unlike a vaccine, monoclonal antibodies provide passive immunity by delivering laboratory-produced antibodies designed to protect infants against severe RSV disease.
The FDA emphasized that Beyfortus is specifically approved for the prevention of RSV lower respiratory tract disease — not RSV infection or upper respiratory tract illness generally.
The agency noted that while the promotional emails later referred to protecting infants from “RSV-LRTI,” lower respiratory tract infection, that clarification did not adequately correct the overall impression created by the broader claims appearing earlier in the communications.
“By failing to adequately communicate the indication for Beyfortus, the emails create a misleading impression about the drug’s FDA-approved indication,” the letter states.
The agency concluded that the promotional materials “misbrand Beyfortus” under the Federal Food, Drug, and Cosmetic Act (FD&C Act).
The FDA requested that Sanofi take immediate action to stop disseminating the promotional communications or other materials containing similar representations.
The agency also instructed the company to submit a written response within 15 working days detailing all Beyfortus promotional communications containing comparable claims, along with its plan to discontinue or correct them.
If Sanofi believes its promotional materials do not violate federal law, FDA said the company may provide its reasoning and supporting evidence as part of its response.
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