UNIVERSAL infant nirsevimab prophylaxis was linked to substantial reductions in respiratory syncytial virus (RSV)-related hospitalisations and outpatient visits, according to new population-based data from Galicia, Spain. The findings provide real-world evidence for clinicians and policymakers considering RSV prevention strategies in infants.
Nirsevimab Prophylaxis in Real-World Settings
The NIRSE-GAL study is an ongoing, longitudinal investigation of nirsevimab under a universal infant immunisation programme. Infants eligible for nirsevimab during the 2023–24 RSV season were followed through the 2024–25 season. Researchers evaluated hospitalisations for RSV-related lower respiratory tract infection (LRTI), acute bronchitis, bronchiolitis, pneumonia, all-cause admissions, and primary care outcomes including wheezing, asthma, and otitis media. First recurrences of these conditions were also tracked. Historical incidence rates from six pre-pandemic RSV seasons were used as comparators, with adjustments for seasonality.
Sustained Reduction in Hospitalisations
Of 12,492 eligible infants, 11,796 (94.4%) received nirsevimab. RSV-related LRTI hospitalisations dropped by 85.9% in the first season and 55.3% in the second season, with 123 infants needing immunisation to prevent a single second-season admission. First LRTI hospitalisations fell by 59.8% in the first season and 48.1% over 18 months. Acute bronchitis or bronchiolitis admissions decreased by around 59% in the first season and remained similarly reduced through 18 months. All-cause hospitalisations declined by 20.3% in the first season, although reductions were not significant thereafter.
Impact on Outpatient Visits
Nirsevimab also lowered outpatient morbidity. First-season visits for bronchitis or bronchiolitis decreased by 30.8%, LRTI visits by 33.4%, and wheezing or asthma visits by 27.7%. First recurrent outpatient visits showed even greater reductions: 52.5% for acute bronchitis or bronchiolitis, 28.2% for wheezing or asthma, and 47.3% for LRTI. These data indicate that nirsevimab not only reduces initial hospital admissions but also diminishes recurrent episodes in the second RSV season.
Implications for Clinical Practice
For clinicians, the findings reinforce nirsevimab’s role in preventing severe RSV disease in infants. Sustained reductions in LRTI hospitalisations and outpatient visits suggest meaningful clinical and healthcare-system benefits. The absence of adverse shifts in RSV morbidity supports safety and long-term effectiveness. Policymakers and healthcare providers can use these data to inform immunisation strategies, optimise resource allocation, and support cost-effectiveness models for universal infant RSV prophylaxis.
Reference
Razzini JL et al. 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. Lancet Infect Dis. 2026; DOI:10.1016/S1473-3099(25)00742-X.
