Nirsevimab Cuts Infant RSV ICU Admissions by 97% in Real-World Canadian Data

The SPRINT-KIDS team examined 2024-2025 RSV season records from seven pediatric hospitals after Ontario and Quebec launched universal nirsevimab programs. Researchers compared infants who received the monoclonal antibody with those who did not, tracking laboratory-confirmed RSV hospitalizations and ICU admissions. Most hospitalized infants were previously healthy, with only 3% having comorbidities, supporting a universal rather than risk-based strategy.

This real-world evidence aligns with earlier randomized trials of nirsevimab but adds Canadian provincial rollout data. The 97% ICU protection exceeds some U.S. observational estimates, possibly reflecting higher uptake or different circulating strains. Funding from public health agencies reduces industry bias concerns, though observational design leaves room for unmeasured confounding such as parental health-seeking behavior.

Next steps include linkage of provincial immunization registries with outcomes across additional seasons and provinces. Policymakers will watch whether effectiveness remains above 70% against ICU admission and whether rare adverse events emerge at population scale before broader Canadian adoption.