Lessons and proposals after a successful strategy against RSV: the Chilean experience with nirsevimab during the 2024 season and challenges for the 2025-2027 period

Abstract

For decades, Respiratory Syncytial Virus (RSV) has been one of the leading causes of morbidity and mortality in infants in Chile and worldwide. The 2023 season, marked by an early and severe out-break, highlighted the limitations of the health system in dealing with this virus, generating broad consensus on the need for a more robust, preventive, and intersectoral strategy. In this context, the creation of the RSV Coalition –an articulated effort between former health authorities, scientific societies, universities, and clinical and technical experts– made it possible to design and promote a series of recommendations that played a significant role in the decision-making process by the health authorities at the time. These efforts materialized in 2024 with the pioneering incorporation of the monoclonal antibody Nirsevimab into the National Immunization Program. Chile thus became the first country in the Southern Hemisphere to implement a national and universal RSV immunization strategy, achieving high coverage rates and substantial reductions in hospitalizations. This article aims to document the positive outcomes of this implementation, as well as to critically reflect on the factors that made it possible, to identify remaining gaps, and –above all– to project the decisions required to prevent setbacks and move toward a sustainable, equitable, evidence-based prevention policy against RSV and other childhood respiratory infections.