Italy's nationwide rollout of nirsevimab — a monoclonal antibody that protects infants against RSV — delivered a 43.6% overall drop in pediatric RSV hospitalizations during the 2024–2025 season, according to a retrospective analysis of nearly 11,000 hospitalizations across 19 pediatric centers over six seasons. The results, published in the International Journal of Infectious Diseases, offer one of the clearest real-world signals yet that RSV prevention in children is working at scale.

But the headline number masks significant regional variation. Regions that launched programs early and made nirsevimab available to a broader group of children saw reductions exceeding 70%, while those with stricter eligibility criteria or delayed rollouts saw only modest declines — or no measurable change at all.

Key Takeaways:

• Regions with the broadest eligibility and earliest program start saw RSV hospitalization reductions of more than 70%
• Regions with stricter or delayed programs saw reductions of only 30–42%, or no clear change
• The overall reduction across all 19 centers was 43.6% in the first nirsevimab season
• Authors note that continued surveillance and harmonized coverage monitoring will be essential to fully assess long-term impact

Why it matters: These findings send a clear message to policymakers: scientific efficacy alone doesn't determine real-world impact. Timely, equitable, and strategically designed immunization programs are essential to maximizing the benefits of nirsevimab — a lesson that likely applies as other countries scale up their own RSV prevention efforts.