Impact of anti-RSV strategies on bronchiolitis across Europe, an interrupted time series analysis
Abstract
Objectives: To compare the real-life impact of various anti-RSV strategies on bronchiolitis visits to pediatric emergency departments (PEDs) across Europe.
Methods: We performed a quasi-experimental controlled interrupted time-series analysis including all bronchiolitis cases in infants under one year presenting to 28 PEDs in 13 European countries between 01/01/18 and 31/03/25. Five strategies were compared: early nirsevimab with catch-up, late nirsevimab with catch-up, early nirsevimab without catch-up, RSVpreF maternal vaccine, and combined nirsevimab/RSVpreF. Seven centers served as controls. Cumulative changes were pooled using meta-analysis and compared using weighted linear regression, adjusting for coverage. Secondary analyses examined specific age groups, severity, and RSV positivity rate.
Results: A total of 130,562 bronchiolitis visits were included. Impact was highly heterogeneous, ranging from −65% (−81 to − 39) in Luxembourg in 2024–2025 (combined nirsevimab/RSVpreF) to + 11% (−21 to + 56) in London in 2024–2025 (RSVpreF maternal vaccine). The reduction in RSV positivity rate was −44% (−57 to − 30). Adjusted for coverage, the combined nirsevimab/RSVpreF strategy showed the greatest reduction (−42%, −40 to − 32), followed by early nirsevimab with catch-up (−31%, −37 to − 25); the difference was not statistically significant (OR 0.89, 0.76 to 1.01). All other strategies showed significantly lower impact, except for infants under 3 months and hospitalized cases, where no difference was observed across strategies.
Conclusions: Different RSV prevention strategies yield significantly different outcomes, underscoring the importance of implementation framework. This study provides real-world comparative evidence to inform national immunization decisions across Europe.
Key messages: • Impact varied across strategies and settings, ranging from −65% to + 11% change in bronchiolitis visits, highlighting that implementation framework is a critical determinant of outcome.
• The combined nirsevimab/RSVpreF and early nirsevimab with catch-up strategies demonstrated the greatest reductions. Overall, target population and timing of implementation emerged as key drivers.
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BibTeX
@article{lenglart2026impact,
title = {{Impact of anti-RSV strategies on bronchiolitis across Europe, an interrupted time series analysis}},
author = {L Lenglart and L Titomanlio and RG Nijman and N Ouldali and E Study group},
journal = {The European Journal of Public Health},
year = {2026},
month = oct,
doi = {10.1093/eurpub/ckag169.461},
url = {https://doi.org/10.1093/eurpub/ckag169.461},
note = {CC BY-NC 4.0},
}
RIS
TY - JOUR
TI - Impact of anti-RSV strategies on bronchiolitis across Europe, an interrupted time series analysis
AU - L Lenglart
AU - L Titomanlio
AU - RG Nijman
AU - N Ouldali
AU - E Study group
PY - 2026
DA - 2026/10/01
JO - The European Journal of Public Health
DO - 10.1093/eurpub/ckag169.461
UR - https://doi.org/10.1093/eurpub/ckag169.461
AB - Objectives: To compare the real-life impact of various anti-RSV strategies on bronchiolitis visits to pediatric emergency departments (PEDs) across Europe. Methods: We performed a quasi-experimental controlled interrupted time-series analysis including all bronchiolitis cases in infants under one year presenting to 28 PEDs in 13 European countries between 01/01/18 and 31/03/25. Five strategies were compared: early nirsevimab with catch-up, late nirsevimab with catch-up, early nirsevimab without catch-up, RSVpreF maternal vaccine, and combined nirsevimab/RSVpreF. Seven centers served as controls. Cumulative changes were pooled using meta-analysis and compared using weighted linear regression, adjusting for coverage. Secondary analyses examined specific age groups, severity, and RSV positivity rate. Results: A total of 130,562 bronchiolitis visits were included. Impact was highly heterogeneous, ranging from −65% (−81 to − 39) in Luxembourg in 2024–2025 (combined nirsevimab/RSVpreF) to + 11% (−21 to + 56) in London in 2024–2025 (RSVpreF maternal vaccine). The reduction in RSV positivity rate was −44% (−57 to − 30). Adjusted for coverage, the combined nirsevimab/RSVpreF strategy showed the greatest reduction (−42%, −40 to − 32), followed by early nirsevimab with catch-up (−31%, −37 to − 25); the difference was not statistically significant (OR 0.89, 0.76 to 1.01). All other strategies showed significantly lower impact, except for infants under 3 months and hospitalized cases, where no difference was observed across strategies. Conclusions: Different RSV prevention strategies yield significantly different outcomes, underscoring the importance of implementation framework. This study provides real-world comparative evidence to inform national immunization decisions across Europe. Key messages: • Impact varied across strategies and settings, ranging from −65% to + 11% change in bronchiolitis visits, highlighting that implementation framework is a critical determinant of outcome. • The combined nirsevimab/RSVpreF and early nirsevimab with catch-up strategies demonstrated the greatest reductions. Overall, target population and timing of implementation emerged as key drivers.
SN - 1101-1262
SN - 1464-360X
ER -