Effectiveness of nirsevimab in infants with acute respiratory infections

Spain introduced universal respiratory syncytial virus (RSV) prophylaxis, making all newborns eligible to receive nirsevimab in the 2023–2024 RSV season. Many Spanish regions also provided the immunization to infants under six months old at the start of the season. This study aimed to evaluate the impact of RSV prophylaxis on the number of infants visiting pediatric emergency departments for acute respiratory infections.

A retrospective study was conducted across 15 pediatric emergency departments in 9 regions from the 2018 to 2024 epidemic seasons (November–January). It compared the 2023–2024 season to previous seasons in terms of lower respiratory tract infections, acute bronchiolitis cases, hospital admissions due to acute bronchiolitis, and PICU admissions.

Results showed a significant 57.7% decrease in lower respiratory tract infections, a 59.2% decrease in acute bronchiolitis cases, a 63.1% reduction in bronchiolitis-related hospital admissions, and a 63.1% reduction in PICU admissionsin the 2023–2024 season. Moreover, regions with extended catch-up immunizations showed better outcomes.

The study concluded that nirsevimab is highly effective in protecting infants from RSV infection, with extended catch-up immunization being the most effective approach. However, cost-effectiveness must also be considered.

Source:Andina Martínez D, Claret Teruel G, Gijón Mediavilla M, Cámara Otegui A, Baños López L, de Miguel Lavisier B, Ferrero García-Loygorri C, Sánchez Tatay V, Pavlovic Nesic S, Clerigué Arrieta N, Gimeno-Hernández Garza V, Guerra Diez JL, Ranera Málaga A, Escalada Pellitero S, Barrueco Ramos C, Alonso-Cadenas JA; Impact of universal Respiratory Syncytial Virus prophylaxis in Spain Working Group. Nirsevimab and Acute Bronchiolitis Episodes in Pediatric Emergency Departments. Pediatrics. 2024 Oct 1;154(4):e2024066584. doi: 10.1542/peds.2024-066584. PMID: 39257372.