Expansion of influenza A(H1N1)pdm09 NA:S247N viruses with reduced susceptibility to oseltamivir, Catalonia, Spain, and in Europe, July to October 2025
Between July and October 2025, among the total 117 influenza A(H1N1)pdm09 strains characterised in Catalonia, 20% to 100% per week were carrying the NA:S247N substitution. The mutation, conferring reduced susceptibility to oseltamivir, was phenotypically confirmed (IC<sub>50</sub> between 0.82 and 1.63 nM, compared to median IC<sub>50</sub> of 0.3 nM for susceptible strains). An increased proportion of S247N variants was also observed in sequence data (10,944 sequences) from other parts of Spain and five of 35 submitting countries across Europe.
Authors
- Ariadna Rando‐Segura (ORCID: https://orcid.org/0000-0003-4555-7286)
- Juliana Esperalba (ORCID: https://orcid.org/0000-0003-1326-1341)
- Narcı́s Saubi (ORCID: https://orcid.org/0000-0001-5493-1044)
- Nieves Larrosa (ORCID: https://orcid.org/0000-0001-8808-0233)
- Alejandra Gónzalez‐Sánchez (ORCID: https://orcid.org/0000-0002-1809-3415)
- Eva Balada (ORCID: https://orcid.org/0000-0002-3059-0633)
- Cristina Andrés (ORCID: https://orcid.org/0000-0002-3200-0895)
- Patricia Nadal‐Barón (ORCID: https://orcid.org/0000-0002-2656-2656)
- Rogério Saad Vaz (ORCID: https://orcid.org/0000-0002-7537-5320)
- Andrés Antón (ORCID: https://orcid.org/0000-0002-1476-0815)
- Jacobo Mendioroz (ORCID: https://orcid.org/0000-0002-8883-2180)
- Rodrigo Vásquez-Mercado
- Ignasi Prats‐Méndez (ORCID: https://orcid.org/0009-0004-0170-9043)
- Maria Arnedo‐Muñoz (ORCID: https://orcid.org/0000-0002-8015-5170)
- Susana Bernalte
- M Vicente
- A. H. Davtyan
- Maria Carmen Martín
- Adrià Najarro
- Karen García-Camuñas
Institutions
- Universitat Autònoma de Barcelona (ES)
- Instituto de Salud Carlos III (ES)
- Departament de Salut (ES)
- Vall d'Hebron Institut de Recerca (ES)
- Centro de Investigación Biomédica en Red (ES)
- Public Health Agency (GB)
- Vall d'Hebron Hospital Universitari (ES)
Publication Details
- Journal
- Eurosurveillance
- Published
- 2025-12-04
- DOI
- https://doi.org/10.2807/1560-7917.es.2025.30.48.2500873
- Citations
- 2
- Primary Topic
- Influenza Virus Research Studies
- Type
- article
- Field-Weighted Citation Impact
- 2.71