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Home > Biblio > Antigenic changes in influenza A(H3N2) driven by genetic evolution: Insights from virological surveillance, EU/EEA, week 40/2023 to week 9/2024

Antigenic changes in influenza A(H3N2) driven by genetic evolution: Insights from virological surveillance, EU/EEA, week 40/2023 to week 9/2024

Health and disease monitoring  
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Published

Peer reviewed scientific article

English

DOI : https://doi.org/10.2807/1560-7917.ES.2024.29.50.2400395 [2]

Authors

Eeva K Broberg [3]; Maja Vukovikj [4]; Olov Svartström [5]; Iris Hasibra [6]; Maximilian Riess [7]; Melidou, Angeliki [8]

Keywords

  1. 2023/24 influenza season [9]
  2. Europe [10]
  3. Influenza H3N2 [11]
  4. influenza virus vaccine [12]

Abstract:

Background During the 2023/24 influenza season in the European Union/European Economic Area (EU/EEA), influenza viruses A(H1N1)pdm09, A(H3N2) and B/Victoria viruses were co-circulating. Aim We aimed to describe the circulating influenza viruses by (sub)type, genetic clade, antigenic group and antiviral susceptibility in that season in the EU/EEA. Methods We collected surveillance data from EU/EEA countries through weekly submissions to The European Surveillance System (TESSy). Data were submitted in strain-based format for weeks 40/2023 to 9/2024. Results Twenty-nine EU…
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Abstract

Background

During the 2023/24 influenza season in the European Union/European Economic Area (EU/EEA), influenza viruses A(H1N1)pdm09, A(H3N2) and B/Victoria viruses were co-circulating.

Aim

We aimed to describe the circulating influenza viruses by (sub)type, genetic clade, antigenic group and antiviral susceptibility in that season in the EU/EEA.

Methods

We collected surveillance data from EU/EEA countries through weekly submissions to The European Surveillance System (TESSy). Data were submitted in strain-based format for weeks 40/2023 to 9/2024.

Results

Twenty-nine EU/EEA countries reported 154,718 influenza virus detections (primary care sentinel and non-sentinel combined), of which 97% (150,692) were type A and 3% (4,026) were type B. Of the subtyped influenza A viruses, 30,463 (75%) were influenza A(H1)pdm09 and 10,174 (25%) were influenza A(H3). For 809 (20%) of the type B viruses, the lineage was determined; all were B/Victoria/2/87 lineage, and none were B/Yamagata/16/88 lineage. Genetic diversification of seasonal influenza viruses continued, and clade 5a.2a of A(H1N1)pdm09, 2a.3a.1 of A(H3N2) and V1A.3a.2 of B/Victoria-lineage viruses dominated. Of the A(H3N2) 2a.3a.1 viruses, 23% were antigenically distinct from the 2023/24 vaccine virus.

Conclusion

The 2023/24 influenza season was characterised by co-circulation of different influenza (sub)types, antigenically similar to the components recommended for the 2023/24 northern hemisphere vaccine, A/Victoria/4897/2022 (egg-based) and A/Wisconsin/67/2022 (cell culture- or recombinant-based). However, genetic diversification of the viruses continued. The World Health Organization’s vaccine recommendations for the northern hemisphere 2024/25 season were updated to include a new A(H3N2) component, while maintaining the current A(H1N1)pdm09 and B/Victoria components.

Associated health topics:

Influenza [13]

Source URL:https://sciensano.be/en/biblio/antigenic-changes-influenza-ah3n2-driven-genetic-evolution-insights-virological-surveillance-eu-eea

Links
[1] https://sciensano.be/sites/default/files/eurosurv-29-50-2.pdf [2] https://doi.org/10.2807/1560-7917.ES.2024.29.50.2400395 [3] https://sciensano.be/en/biblio?f%5Bauthor%5D=190280&f%5Bsearch%5D=Eeva%20K%20Broberg [4] https://sciensano.be/en/biblio?f%5Bauthor%5D=190281&f%5Bsearch%5D=Maja%20Vukovikj [5] https://sciensano.be/en/biblio?f%5Bauthor%5D=190282&f%5Bsearch%5D=Olov%20Svartstr%C3%B6m [6] https://sciensano.be/en/biblio?f%5Bauthor%5D=190283&f%5Bsearch%5D=Iris%20Hasibra [7] https://sciensano.be/en/biblio?f%5Bauthor%5D=190284&f%5Bsearch%5D=Maximilian%20Riess [8] https://sciensano.be/en/biblio?f%5Bauthor%5D=190285&f%5Bsearch%5D=Melidou%2C%20Angeliki [9] https://sciensano.be/en/biblio?f%5Bkeyword%5D=38729&f%5Bsearch%5D=2023/24%20influenza%20season [10] https://sciensano.be/en/biblio?f%5Bkeyword%5D=42&f%5Bsearch%5D=Europe [11] https://sciensano.be/en/biblio?f%5Bkeyword%5D=38728&f%5Bsearch%5D=Influenza%20H3N2 [12] https://sciensano.be/en/biblio?f%5Bkeyword%5D=38730&f%5Bsearch%5D=influenza%20virus%20vaccine [13] https://sciensano.be/en/health-topics/influenza