AZ, Sanofi closing in on first approval for RSV in 23 years

April 27, 2023

AstraZeneca and Sanofi have reported positive topline results from a study of a vaccine for respiratory syncytial virus (RSV) — the leading cause of bronchitis in infants.

RSV infections impact most infants and can become serious. Estimates show that RSV infections lead to an estimated 80,000 hospitalizations and cause about 500 deaths in children in the U.S. each year. Currently, the only treatment option is AstraZeneca’s Synagis, which was developed to provide protection from the virus for one month in high-risk children.

But in a partnership with Sanofi, AstraZeneca developed nirsevimab, an antibody that could protect children from RSV for a five-month season with a single dose.

Although the companies did not provide detailed data from their phase 3 trial of nirsevimab — which was conducted before the pandemic — the companies said that the drug hit its primary efficacy endpoint.

Nirsevimab has received breakthrough designation in the U.S., EU and China. No other drug has been approved to treat RSV in 23 years.

The companies now say that more data on the vaccine will be released soon at a medical conference.