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."