Nirsevimab delivers 83 percent reduction in RSV infant hospitalizations in a real world clinical trial setting: Sanofi

The Hospitalized RSV Monoclonal Antibody Prevention (HARMONIE) study is a large, multi-country European interventional clinical trial aiming to determine the efficacy and safety of a single intramuscular dose of nirsevimab, with data collected in a real-world setting during the 2022-2023 RSV season. The trial recruited more than 8,000 infants and took place at nearly 250 sites across France, Germany and the United Kingdom. The data from HARMONIE were presented at the 41st Annual Meeting of the European Society for Paediatric Infectious Diseases (ESPID).

Thomas Triomphe, Executive Vice President, Vaccines, Sanofi said, “This winter saw higher rates of RSV-related infant hospitalizations than during pandemic or pre-pandemic years. The HARMONIE data demonstrate the real-world impact nirsevimab has on pediatric hospitalizations, and illustrate its importance for infants, their families and public health.”

Dr Simon Drysdale, Consultant Pediatrician in Infectious Diseases at St. George’s University Hospital NHS Foundation Trust and Co-Chief Investigator of HARMONIE said, “RSV-related chest infections lead to high numbers of infants under 12 months old being hospitalized every year. These data reinforce the potential public health benefit of nirsevimab in terms of helping to reduce the strain on hospitals caused each year by RSV.”

The data from HARMONIE also show that nirsevimab reduced the incidence of hospitalizations due to severe RSV-related LRTD (patients whose oxygen level is under 90% and require oxygen supplementation) by 75.71% (95% CI 32.75 to 92.91; P<0.001).

Additionally, nirsevimab demonstrated a reduction of 58.04% (95% CI 39.69 to 71.19; P<0.001) in the incidence of all-cause LRTD hospitalization compared to infants who received no RSV intervention. This means the overall burden on healthcare systems could be reduced significantly if all infants receive nirsevimab. RSV-related direct medical costs, globally — including hospital, outpatient and follow-up care — were estimated at €4.82 billion in 2017.

Throughout HARMONIE, nirsevimab maintained a favorable safety profile, consistent with the pivotal trial results.