> ## Content Index
> Fetch the complete content index at: https://www.fdaweb.com/llms.txt
> Use this file to discover other available public pages before exploring further.

# Data Reinforce Nirsevimab RSV Efficacy: Sanofi/AstraZeneca
- URL: https://www.fdaweb.com/data-reinforce-nirsevimab-rsv-efficacy-sanofi-astrazeneca/
- Published: 2022-05-11T12:00:00.000Z
- Updated: 2026-09-14T17:44:16.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5151790

Sanofi and AstraZeneca say a pre-specified pooled analysis of Phase 3 and Phase 2b data demonstrates efficacy of 79.5% for their nirsevimab against medically attended lower respiratory tract infections, including hospitalizations, caused by the respiratory syncytial virus (RSV). A Sanofi media [statement](https://www.sanofi.com/en/media-room/press-releases/2022/2022-05-11-08-00-00-2440425?ref=fdaweb.com) says the safety profile across the nirsevimab and placebo groups as reported in previous trials remains similar.

“These findings contribute to the growing body of evidence suggesting that nirsevimab can protect all infants through their first RSV season with a single dose,” the statement says.

Nirsevimab is described as an investigational long-acting antibody designed to protect all infants from birth entering their first RSV season with a single dose. FDA has granted it breakthrough therapy designation.