Real-World Effectiveness of Nirsevimab: Evidence from the NIRSE-GAL Study

Study Design and Methodology of the NIRSE-GAL Study in Galicia

The NIRSE-GAL study is an ongoing population-based, prospective, longitudinal study conducted in Galicia, Spain. It includes infants eligible to receive nirsevimab and evaluates its impact on RSV-related outcomes in both inpatient and outpatient healthcare settings.¹

NIRSE-GAL: Population-Based Prospective Study of Nirsevimab in Infants (1)

Clinical Outcomes from the NIRSE-GAL Study in Infants Receiving Nirsevimab

Clinical outcomes were compared with historical RSV seasons before the introduction of nirsevimab to evaluate reductions in RSV-related clinical events. The primary endpoint was RSV-related LRTI hospitalisation.¹

Primary Outcome of the NIRSE-GAL Study (1)

RSV-related LRTI hospitalisations were assessed from their first RSV (2023-24) until the end of their second RSV season (2024-25).

RSV-Related LRTI Hospitalisations Across Two Seasons

Nirsevimab prophylaxis showed sustained reductions in RSV-related LRTI hospitalisations across two seasons.

Secondary Outcomes of the NIRSE-GAL Study

Secondary endpoints included LRTI hospitalisation, acute bronchitis or bronchiolitis hospitalisation, and all-cause hospitalisation.¹

Secondary Outcomes of NIRSE-GAL Study Across Two Seasons (1) 

Recurrence and Outpatient Outcomes

First recurrent hospitalisations in the second RSV season decreased significantly:
78.2% for RSV-related LRTI, 62.4% for LRTI, and 76.9% for acute bronchitis or bronchiolitis.¹

Outpatient visits related to respiratory illnesses, including bronchitis, bronchiolitis, wheezing, and asthma, also declined, suggesting a broader reduction in healthcare burden and potential economic benefits.¹

Conclusion

Universal nirsevimab prophylaxis in the NIRSE-GAL study significantly reduced RSV-related hospitalisations and outpatient morbidity, with sustained reductions extending into the second RSV season.¹ These findings provide strong population-level evidence supporting infant immunization strategies and cost-effectiveness evaluations.¹