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Nirsevimab and Acute Bronchiolitis Episodes in Pediatric Emergency Departments
David Andina Martínez1,2, Gemma Claret Teruel3,4,5, Manuel Gijón Mediavilla6
1Pediatric Emergency Department, Hospital Infantil Universitario Niño Jesús, Madrid, Spain.
Insights
Universal nirsevimab prophylaxis significantly reduced respiratory syncytial virus (RSV) infections in infants. This universal RSV immunization strategy, including extended catch-up, proved highly effective in preventing lower respiratory tract infections and hospitalizations.
Area of Science:
- Pediatric infectious diseases
- Immunization strategies
- Public health interventions
Background:
- Spain implemented universal nirsevimab prophylaxis for infants during the 2023-2024 respiratory syncytial virus (RSV) season.
- Many regions also offered extended catch-up immunization for infants under 6 months.
- This study evaluated the impact of RSV prophylaxis on pediatric emergency department visits for acute respiratory infections.
Purpose of the Study:
- To assess the effect of universal RSV prophylaxis with nirsevimab on infant emergency department presentations.
- To compare RSV-related illness rates before and after the widespread implementation of nirsevimab.
- To evaluate the effectiveness of different prophylaxis approaches, including extended catch-up programs.
Main Methods:
- A retrospective study analyzed data from 15 Spanish pediatric emergency departments across 9 regions.
- The study compared epidemic seasons from 2018-2023 with the 2023-2024 season.
- Key metrics included lower respiratory tract infections, acute bronchiolitis episodes, hospital admissions, and PICU admissions.
Main Results:
- A significant decrease was observed in 2023-2024: 57.7% fewer lower respiratory tract infections and 59.2% fewer acute bronchiolitis episodes.
- Hospital admissions for acute bronchiolitis decreased by 63.1%, and PICU admissions also dropped by 63.1%.
- Regions employing extended catch-up immunization strategies demonstrated superior outcomes.
Conclusions:
- Nirsevimab provides highly effective protection for a broad infant population against RSV.
- Universal prophylaxis, particularly when combined with extended catch-up programs, is the most effective strategy.
- Cost-effectiveness considerations remain important for widespread implementation.
Background And Objectives:
In the 2023-2024 respiratory syncytial virus (RSV) season, Spain became one of the first countries to introduce universal RSV prophylaxis, during which all infants born at this time were eligible to receive nirsevimab. Locally, most Spanish regions also immunized infants younger than age 6 months at the start of the season (extended catch-up). The aim of this study was to assess how RSV prophylaxis affected the number of infants presenting to pediatric emergency departments with acute respiratory infections.
Methods:
A retrospective study was conducted in 15 Spanish pediatric emergency departments from 9 different regions between the 2018 and 2024 epidemic seasons (November-January). We compared the seasons occurring in 2018-2023 and the 2023-2024 season regarding the number of episodes of lower respiratory tract infection and acute bronchiolitis, acute bronchiolitis-related hospital admissions, and PICU admissions.
Results:
A comparison with the average rates for the previous epidemic seasons revealed a 57.7% decrease in episodes of lower respiratory tract infection in 2023-2024 (95% CI, 56.5-58.8; P < .001; range among hospitals, 4.8-82.8), a 59.2% decrease in episodes of acute bronchiolitis (95% CI, 57.9-60.4; P < .001; range, 6.9-84.1), a 63.1% reduction in acute bronchiolitis-related hospital admissions (95% CI, 60.9-65.2; P < .001; range, 31.4-86.8), and a 63.1% reduction in PICU admissions (95% CI, 58.1-67.9; P < .001; range, 18.2-81.8). Hospitals in regions applying extended catch-up showed better results.
Conclusions:
Nirsevimab can protect a broad infant population against RSV infection with high effectiveness. Approaches including extended catch-up are the most effective, although cost- effectiveness must be considered.
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