Evidence on Nirsevimab: Sustained Impact Across Two RSV Seasons

Impact of universal nirsevimab prophylaxis in infants on hospital and primary care outcomes across two respiratory syncytial virus seasons in Galicia, Spain (NIRSE-GAL): A population-based prospective observational study

Study Objective

Results: 
Impact on Key Hospitalization Outcomes

Additional outcome including pneumonia, was also analyzed (refer manuscript for full results).
CI, Confidence Interval; LRTI, Lower Respiratory Tract Infection; RSV, Respiratory Syncytial Virus.

Results: 
RSV-Related LRTI Hospitalization Over Time

As illustrated in the graph above:

• Immediate and substantial reduction in RSV burden: During the first RSV season, observed hospitalizations remain near zero compared to the high expected peak.
• Sustained protection into the second RSV season: The gap between expected and observed hospitalizations persists into the second season,demonstrating a carry-over effect beyond the initial season of protection.
• No evidence of rebound: The second-season data does not show an increase above expected levels, supporting no shift toward delayed or more severe disease.

Adapted from Razzini J L, et al. Available at: https://doi.org/10.1016/S1473-3099(25)00742-X.
Observed (green) and expected (blue) weekly RSV-related LRTI hospitalizations with 95% CIs (shaded bands) across first RSV season, second RSV season, and up to 18 months follow-up. Expected counts assume no immunization for the 2023-24 cohort.
CI, Confidence interval; LRTI, Lower Respiratory Tract Infection; RSV, Respiratory Syncytial Virus.