Effectiveness of catch-up and at-birth nirsevimab immunisation against RSV hospital admission in the first year of life: a population-based case–control study, Spain, 2023/24 season

BackgroundRespiratory syncytial virus (RSV) causes substantial morbidity in infants < 1 year. In October 2023, Spain recommended the monoclonal antibody nirsevimab to all children born since 1 April 2023, at birth or as catch-up if born before October 2023.AimWe estimated nirsevimab effectiveness in preventing RSV hospitalisations during the 2023/24 season.MethodsWe conducted a nationwide population-based matched case-control study. Cases were children hospitalised for lower respiratory tract infection who were RSV PCR-positive. For each case, we selected four population density controls born in the same province and date (±2 days). We defined at-birth immunisation as receiving nirsevimab during the first 2 weeks of life, and catch-up immunisation within 30 days from campaign onset. Causal intention-to-treat (ITT) and per-protocol (PP) effectiveness was estimated using inverse-probability-of-immunisation weighted conditional logistic regression.ResultsWe included 406 cases and 1,623 controls in catch-up and 546 cases and 2,182 controls in at-birth immunisation studies. Effectiveness in preventing RSV hospitalisations for catch-up immunisation was 71% (95% confidence interval (CI): 65-76) by ITT and 80% (95% CI: 75-84) PP. Effectiveness for at-birth immunisation was 78% (95% CI: 73-82) by ITT and 83% (95% CI: 79-87) PP. Effectiveness was similar for ICU admission, need of mechanical ventilation, and RSV viral subgroups A and B. Children born pre-term or with birthweight < 2,500 g showed lower PP effectiveness of 60-70%.ConclusionsPopulation-level nirsevimab immunoprophylaxis in children in their first RSV season was very effective in preventing RSV hospitalisations, ICU admission and mechanical ventilation, with reduced but still high effectiveness for pre-term and low-birthweight children.

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Publication Details

Journal
Eurosurveillance
Published
2025-02-06
DOI
https://doi.org/10.2807/1560-7917.es.2025.30.5.2400596
Citations
19
Primary Topic
Respiratory viral infections research
Type
article
Field-Weighted Citation Impact
25.73
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article

Effectiveness of catch-up and at-birth nirsevimab immunisation against RSV hospital admission in the first year of life: a population-based case–control study, Spain, 2023/24 season

María Isabel Barranco, María de los Ángeles Díaz Domínguez, Olivier G. Nunez, Pello Latasa Zamalloa et al.
19 citations
Eurosurveillance
Respiratory viral infections research
25.73
article

Effectiveness of catch-up and at-birth nirsevimab immunisation against RSV hospital admission in the first year of life: a population-based case–control study, Spain, 2023/24 season

María Isabel Barranco, María de los Ángeles Díaz Domínguez, Olivier G. Nunez, Pello Latasa Zamalloa, Ana Carmen Ibáñez Pérez, María Victoria García Rivera, Aurora Limia, Manuel Garcìa Cenoz, Susana Monge, Cristina Andreu‐Vázquez, Inmaculada Jarrín, Manuel Galán Cuesta, Sara Josefina Ibarra Montenegro, Roberto Pastor‐Barriuso, Ana Fernández Ibáñez, Manuel Pacheco, Marcos Alonso-García, Olaia Pérez‐Martínez, Manuel Méndez Díaz, David Moreno‐Pérez, Eva Rivas Wagner, Sergio Fernández Martínez, Enriqueta Muñoz Platón, Jacobo Mendioroz, Rosa Álvarez-Gil, Begoña Adiego Sancho, Virginia Álvarez Río, Nieves López González‐Coviella, Montserrat Martínez, Nicola Lorusso, Matilde Zornoza, Roxana Morey Arance, Noa Batalla, Luisa Hermoso, Miguel Fiol Jaume, Jesús Castilla, Belén Berradre Sáenz, Marta Huerta Huerta, J.M. Aragoneses Lamas, Pedro Eliseo Pastor Villalba, Ángeles Gutierrez, Rosa Sancho, Susana Casado Cobo, Carmen Olmedo
article en
19 citations

Abstract

BackgroundRespiratory syncytial virus (RSV) causes substantial morbidity in infants < 1 year. In October 2023, Spain recommended the monoclonal antibody nirsevimab to all children born since 1 April 2023, at birth or as catch-up if born before October 2023.AimWe estimated nirsevimab effectiveness in preventing RSV hospitalisations during the 2023/24 season.MethodsWe conducted a nationwide population-based matched case-control study. Cases were children hospitalised for lower respiratory tract infection who were RSV PCR-positive. For each case, we selected four population density controls born in the same province and date (±2 days). We defined at-birth immunisation as receiving nirsevimab during the first 2 weeks of life, and catch-up immunisation within 30 days from campaign onset. Causal intention-to-treat (ITT) and per-protocol (PP) effectiveness was estimated using inverse-probability-of-immunisation weighted conditional logistic regression.ResultsWe included 406 cases and 1,623 controls in catch-up and 546 cases and 2,182 controls in at-birth immunisation studies. Effectiveness in preventing RSV hospitalisations for catch-up immunisation was 71% (95% confidence interval (CI): 65-76) by ITT and 80% (95% CI: 75-84) PP. Effectiveness for at-birth immunisation was 78% (95% CI: 73-82) by ITT and 83% (95% CI: 79-87) PP. Effectiveness was similar for ICU admission, need of mechanical ventilation, and RSV viral subgroups A and B. Children born pre-term or with birthweight < 2,500 g showed lower PP effectiveness of 60-70%.ConclusionsPopulation-level nirsevimab immunoprophylaxis in children in their first RSV season was very effective in preventing RSV hospitalisations, ICU admission and mechanical ventilation, with reduced but still high effectiveness for pre-term and low-birthweight children.

EurosurveillanceVol. 30(5)
Instituto de Salud Carlos III (ES), Instituto de Salud Pública de Navarra (ES), Ministry of Health (ES), Department of Health (ES), Centre for Biomedical Network Research on Rare Diseases (ES), Gobierno de Aragón (ES), Centro de Tecnologías Aeronauticas (Spain) (ES), Hospital Universitario Son Espases (ES), Centro de Investigación Biomédica en Red de Epidemiología y Salud Pública (ES), Individual Differences (US), Instituto de Investigación Biomédica de Málaga (ES)
Good health and well-being
Openalex Percentile: Top 0%
Respiratory viral infections research
25.73
DOIOpen Access PDFOpenAlex
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