Manzanares, ÁngelaPardo Seco, Jacobo JoséRivero Calle, IreneDacosta Urbieta, Ana IsabelMallah, NarmeenRodríguez-Tenreiro Sánchez, CarmenSalas Ellacuriaga, AntonioMartinón Torres, Federico2025-07-152025-07-152025-05-02Manzanares, A., Pardo-Seco, J., Rivero-Calle, I. et al. Respiratory syncytial virus–related lower respiratory tract infection hospitalizations in infants receiving nirsevimab in Galicia (Spain): the NIRSE-GAL study. Eur J Pediatr 184, 321 (2025). https://doi.org/10.1007/s00431-025-06151-30340-6199https://hdl.handle.net/10347/42474As part of the NIRSEGAL study (https://www.nirsegal.es/en), we present the clinical characteristics and course of respiratory syncytial virus (RSV)-related low respiratory tract infection (LRTI) hospitalizations in infants eligible for nirsevimab administration during the 2023–2024 season. Infants eligible for nirsevimab immunization (born between 1 April, 2023, and 30 March, 2024) who were hospitalized due to RSV-related LRTI between September 25, 2023, and April 15, 2024, in a hospital from the Galician Public Health system were included. Clinical and demographic characteristics of RSV-related LRTI hospitalizations were analyzed, with comparisons made between breakthrough cases (those immunized with nirsevimab) and non-breakthrough cases. During the study period, 69 RSV-related LRTI hospitalizations were recorded, with a median hospital stay of 4 (interquartile range (IQR) 3–6) days; 65.2% (N=45) were breakthrough cases. The median age was 2.7 (IQR 1.5–5.2) months, and more than half of them (N=39, 56.5%) were male. The incidence of cases was parallel to the RSV epidemic curve, suggesting no waning of nirsevimab efcacy. Of the total hospitalizations, 16 infants (23.2%) had a high-risk condition, 44 (63.8%) needed oxygen support, 15 (21.7%) were admitted to the intensive care unit (ICU), and 11 (15.9%) received non-invasive mechanical ventilation (NIMV). No statistically signifcant diferences were observed in these characteristics when comparing breakthrough and non-breakthrough cases. Conclusion: In the nirsevimab era, a substantial proportion of children who were hospitalized for RSV-related LRTI needed oxygen support, NIMV, and ICU admission. Clinical characteristics, timing, and outcomes were comparable between breakthrough and non-breakthrough cases. Trial registration: The NIRSE-GAL study protocol was registered on ClinicalTrials.gov (NCT06180993).eng© The Author(s) 2025. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.Attribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/Respiratory syncytial virus (RSV)Low respiratory tract infection (LRTI)NirsevimabBreakthrough casesImmunizationInfantsjournal article10.1007/s00431-025-06151-3open access