Respiratory syncytial virus: "very promising results" for Sanofi-AstraZeneca treatment

French laboratory Sanofi claimed "very promising results" on Friday after a large study was conducted on its preventive treatment nirsevimab, co-developed with British firm AstraZeneca, aimed at reducing the risk of hospitalization for infants with respiratory syncytial virus (RSV).

This drug, the world's first approved preventive treatment for RSV, which causes bronchiolitis, "prevented 83.21% of hospitalizations in infants under twelve months who received a single dose of nirsevimab, compared to infants who received no intervention" against the virus, Sanofi said in a statement.

This finding is the result of a phase three study involving more than 8,000 children in France, Germany, and the United Kingdom, using real-world data collected during the 2022-2023 RSV circulation season.

"The overall burden on healthcare systems could be significantly reduced if nirsevimab was administered to all infants. In 2017, direct healthcare expenses related to RSV (including hospital care, outpatient visits, and follow-up care) were estimated at €4.82 billion worldwide," Sanofi said.

Currently, nine out of ten children are infected with RSV before the age of two. Although the infection is generally mild, nearly one in three children who go to the emergency room for bronchiolitis require hospitalization.

According to a French national study conducted from 2010 to 2018, an average of 50,878 children under the age of five are hospitalized each year due to RSV. Among them, children under one year old represent more than 69% of hospitalizations, or more than 35,000 children per year, Sanofi recalls.

Nirsevimab has received marketing authorization in the European Union, the United Kingdom, and Canada for the prevention of lower respiratory tract infections caused by RSV in newborns and infants during their first RSV exposure season.

In addition, its approval request is under review in the United States.