How a major discovery can become a public health failure when used subotptimally: lessons from early nirsevimab...

In this Debate, based on our clinical data from the "pre-nirsevimab" and "first year of nirsevimab implementation" bronchiolitis seasons, we challenge the validity of policy decisions that led to partial immunization coverage of eligible newborns and infants during the 2024-25 season in Italy.

Starting with a pre-nirsevimab prospective cohort of 780 newborns, we documented that 84 (9.2%) were diagnosed with acute bronchiolitis (45 of them (5.8% of the cohort) were RSV positive. 44 patients (5.6%) were hospitalized due to bronchiolitis, of which 7 (0.9%) patients were admitted to the Pediatric Intensive Care Unit. Among hospitalized, 31 infants (70%) had RSV infection. Secondly, we evaluated the impact on bronchiolitis admissions during the first year of nirsevimab use in our region, showing a negligible effect on the most severe cases, probably due to the fact that a low coverage will risk to miss the relatively small number of infants (about 10%) that will develop RSV bronchiolitis in the first year of life. These findings inspired our clinical insights and reflections arguing that without a long-term, cost-conscious approach to implementation, even major scientific breakthroughs like nirsevimab risk becoming public health failures.

Our clinical insights and reflections aim to inspire deeper engagement among policymakers, health agencies, and clinicians to better adapt and integrate RSV preventive strategies-maximizing benefit not only for susceptible infants, but for society at large. In a world of finite healthcare resources, optimizing both the reach and the value of such essential interventions is imperative, given the multitude and diversity of health needs our society is facing.