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. 2025 Nov;30(45):2500816.
doi: 10.2807/1560-7917.ES.2025.30.45.2500816.

Effectiveness of long-acting monoclonal antibodies against laboratory-confirmed RSV in children aged < 24 months and hospitalised for severe acute respiratory infection, European pilot study, 2024 to 2025

Camelia Savulescu  1 , Iris Ganser  1 , Nathalie Nicolay  2 , Adrien Lajot  3 , Sandra Campos  4   5 , Iván Martínez-Baz  6   7 , Ana Paula Rodrigues  8 , Mathil Vandromme  3 , Marta Cara-Rodríguez  9 , Aitziber Echeverría  6   7 , Vânia Gaio  8 , Marie-Pierre Parsy  10 , Ana Roldan Garrido  11 , Jesús Castilla  6   7 , Raquel Guiomar  12 , Sabrina Bacci  2 , Angela Mc Rose  1 ; VEBIS hospital network RSV IE group  13
Collaborators, Affiliations

Effectiveness of long-acting monoclonal antibodies against laboratory-confirmed RSV in children aged < 24 months and hospitalised for severe acute respiratory infection, European pilot study, 2024 to 2025

Camelia Savulescu et al. Euro Surveill. 2025 Nov.

Abstract

We measured effectiveness of nirsevimab against laboratory-confirmed respiratory syncytial virus (RSV) infection in a test-negative case-control study among children aged < 24 months hospitalised for severe acute respiratory infection in three European countries. The overall effectiveness in the 2024/25 season among 2,201 children was 79% (95% CI: 58 to 89) and 85%, 78% and 69% at < 30, 30-89 and 90-215 days since immunisation. Immunisation was effective for preventing RSV-related hospitalisation in children, but effectiveness by time since immunisation needs monitoring in future seasons.

Keywords: Europe; RSV; monoclonal antibodies, nirsevimab, effectiveness.

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Conflict of interest statement

Conflict of interest: APR reported honoraria from Sanofi for a lecture on RSV, MV reported national funding from SARI surveillance from Belgian Public Services (FPS Santé Publique).

Collaborators from the VEBIS hospital network RSV IE group: NDa reported grants from Sciensano and MSD, honoraria for lectures from Astra Zeneca, support for attending meetings from MSD, Gilead, ViiV healthcare, Eumedica (payments made to the institution), and participation in Advisory board of MSD in the past 36 months. CB reported an 8-month contract as project officer with European Public Health Association (EUPHA) in the past 36 months. SDa reported support for attending ESPID 2025 from Sanofi-Pasteur. CB, LDM, PM, SH, YD, YL, NB reported national funding for SARI surveillance from Belgian Public Services (FPS Santé Publique).

All other authors declare no conflicts of interest related to this work.

Figures

Flowchart for inclusion into the RSV immunisation effectiveness pilot study among hospitalised children aged < 24 months in Europe during the 2024/25 season. This details the reasons for exclusions, allowing us to arrive at the final number of cases and controls included in analysis.
Figure 1
Inclusion and exclusion criteria for the VEBIS RSV immunisation effectiveness multicentre hospital study, Europe, 2024/25 season (n = 4,102)
Bar charts showing the number of patients (children aged < 24 months) hospitalised with severe acute respiratory infection in participating European hospitals, by week of their symptom onset, during the 2024/25 season. Patients are shown as PCR-positive cases of RSV or as controls (RSV-negative). The line graph indicates the week of immunisation for these patients.
Figure 2
Distribution of hospitalised RSV cases and controls, by date of symptom onset, and distribution of included immunised patients, by week of immunisation, VEBIS immunisation effectiveness multicentre hospital study, Europe, 2024/25 season (n = 2,201)
Effectiveness of immunisation with monoclonal antibody against respiratory syncytial virus among children aged <24 months in participating hospitals in Europe during the 2024/25 season. Graph shows effectiveness overall and for those aged 0–6 and 7–23 months separately, for the entire study period and by time since immunisation (< 30, 30–89 and ≥ 90 days).
Figure 3
Immunisation effectiveness against RSV in children aged < 24 months, by age group and time since immunisation, 2-stage pooled analysis, VEBIS multicentre hospital study, Europe, 2024/25 seasona, b
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References

    1. European Medicines Agency (EMA). Beyfortus (nirsevimab). Amsterdam; EMA: Jul 2024. Available from: https://www.ema.europa.eu/en/documents/overview/beyfortus-epar-medicine-...
    1. World Health Organization (WHO) . WHO position paper on immunization to protect infants against respiratory syncytial virus disease, May 2025. Wkly Epidemiol Rec. 2025;22(100):193-218.
    1. European Centre for Disease Prevention and Control (ECDC). Operational considerations for respiratory virus surveillance in Europe. Stockholm: ECDC; 18 Jul 2022. Available from: https://www.ecdc.europa.eu/en/publications-data/operational-consideratio...
    1. Ministerio de Sanidad (Sanidad). Recomendaciones de inmunización pasiva para prevención de enfermedad grave por VRS en la población infantil. [Passive immunization recommendations for the prevention of severe RSV disease in children]. Madrid: Sanidad; Nov 2024. Spanish. Available from: https://www.sanidad.gob.es/areas/promocionPrevencion/vacunaciones/comoTr...
    1. Direção Geral da Saúde (DGS). Imunização Sazonal contra o Vírus Sincicial Respiratório em Idade Pediátrica: Outono-Inverno 2024-2025. [Seasonal immunisation against respiratory syncytial virus in paediatric population: Autumn-Winter 2024-2025]. Lisboa: DGS; 12 Aug 2024. Portuguese. Available from: https://www.spp.pt/UserFiles/file/DOCUMENTOS%20OFICIAIS/Norma%2005_2024_...

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