AstraZeneca-Sanofi's Nirsevimab Shows 75% Efficacy Against RSV In Healthy Infants

AstraZeneca Plc AZN and Sanofi SA SNY have shared detailed results from the MELODY Phase 3 trial evaluating nirsevimab in respiratory syncytial virus (RSV).
The data showed that a single dose of nirsevimab met the primary efficacy endpoint reducing the incidence of medically attended lower respiratory tract infections caused by RSV by 74.5% compared to placebo.
The trial also evaluated nirsevimab in infants with congenital heart disease, chronic lung disease, and prematurity.
The data demonstrated nirsevimab had similar safety and tolerability profile compared to Swedish Orphan Biovitrum AB's Synagis (palivizumab), the only available preventative option for RSV.
A prespecified pooled analysis of the MELODY and Phase 2b trials demonstrated a reduction of hospitalizations caused by RSV with the proposed dose of nirsevimab.
In term and preterm infants, 21 of 786 (2.7%) infants in the placebo arm compared to nine of 1,564 (0.6%) in the nirsevimab arm experienced an RSV-associated hospitalization, giving an estimated efficacy of 77.3%.
Although not statistically significant, there was a numerical reduction of the risk of RSV-associated hospitalizations observed in the MELODY trial alone.
Price Action: AZN shares are down 3.09% at $60.09, SNY stock is down 1.02% at $50.54 during the market session on the last check Thursday.