Global impact of nirsevimab on respiratory syncytial virus: Valle d’Aosta and beyond

ABSTRACT
Respiratory syncytial virus (RSV) is a leading cause of bronchiolitis and pneumonia in infants, with significant morbidity and mortality worldwide. Despite advancements in medical care, RSV continues to impose a substantial economic and emotional burden on families. Current preventive measures, such as the monoclonal antibody palivizumab, are limited to high-risk populations due to cost and administration frequency. Recently, a new prophylactic agent, nirsevimab, has become available for protection of all infants and children during their first RSV season.
Nirsevimab is a humanized monoclonal antibody that targets the fusion (F) protein of RSV in its prefusion conformation, a critical structure for viral infectivity. Nirsevimab has shown an extended half-life and broad neutralizing activity against various RSV strains, including those resistant to other antibodies.
This review focuses on implementation of universal nirsevimab prophylaxis, including the pivotal Italian experience in the Valle d’Aosta region, during the 2023-2024 epidemic season.
Data from the region indicate a significant reduction in RSV hospitalizations among infants who received nirsevimab, with no hospitalizations reported in this group compared to 9.7% hospitalization rate in the non-prophylaxis group. Side effects were mild and short-lived. The findings suggest that universal nirsevimab prophylaxis is an effective and safe strategy for reducing the burden of RSV in infants, aligning with successful programs in other countries, such as USA, Spain and France.
Further research is needed to explore its long-term impact and cost-effectiveness. By addressing these questions, nirsevimab can play a crucial role in improving infant health outcomes and reducing the burden of RSV.

Received: July 31, 2024
Accepted: Sept 23, 2024