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. 2024 Sep;29(39):2400020.
doi: 10.2807/1560-7917.ES.2024.29.39.2400020.

Co-circulation of seasonal influenza A(H1N1)pdm09, A(H3N2) and B/Victoria lineage viruses with further genetic diversification, EU/EEA, 2022/23 influenza season

Eeva K Broberg  1 , Olov Svartström  1 , Maximilian Riess  1 , Annette Kraus  1 , Maja Vukovikj  1 , Angeliki Melidou  1 ; Members of the European Reference Laboratory Network for Human Influenza (ERLI-Net)  2 ; Collaborators
Collaborators, Affiliations

Co-circulation of seasonal influenza A(H1N1)pdm09, A(H3N2) and B/Victoria lineage viruses with further genetic diversification, EU/EEA, 2022/23 influenza season

Eeva K Broberg et al. Euro Surveill. 2024 Sep.

Abstract

BackgroundInfluenza viruses can cause large seasonal epidemics with high healthcare impact and severity as they continually change their virological properties such as genetic makeup over time.AimWe aimed to monitor the characteristics of circulating influenza viruses over the 2022/23 influenza season in the EU/EEA countries. In addition, we wanted to compare how closely the circulating viruses resemble the viral components selected for seasonal influenza vaccines, and whether the circulating viruses had acquired resistance to commonly used antiviral drugs.MethodsWe performed a descriptive analysis of the influenza virus detections and characterisations reported by National Influenza Centres (NIC) from the 30 EU/EEA countries from week 40/2022 to week 39/2023 to The European Surveillance System (TESSy) as part of the Global Influenza Surveillance and Response System (GISRS).ResultsIn the EU/EEA countries, the 2022/23 influenza season was characterised by co-circulation of A(H1N1)pdm09, A(H3N2) and B/Victoria-lineage viruses. The genetic evolution of these viruses continued and clade 6B.1A.5a.2a of A(H1N1)pdm09, 3C.2a1b.2a.2b of A(H3N2) and V1A.3a.2 of B/Victoria viruses dominated. Influenza B/Yamagata-lineage viruses were not reported.DiscussionThe World Health Organization (WHO) vaccine composition recommendation for the northern hemisphere 2023/24 season reflects the European virus evolution, with a change of the A(H1N1)pdm09 component, while keeping the A(H3N2) and B/Victoria-lineage components unchanged.

Keywords: Europe; characterisation; genetic; influenza virus; sequencing; surveillance.

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Conflict of interest statement

Conflict of interest: None declared.

Figures

Figure 1
Figure 1
Number of viruses by antigenic group or assigned genetic clade by subtype, EU/EEA, weeks 40/2022–39/2023 (n = 1,642)
Figure 2
Figure 2
Phylogenetic comparison of influenza A(H1N1)pdm09 haemagglutinin genes, EU/EEA, weeks 40/2022–39/2023 (n = 2,466)
Figure 3
Figure 3
Phylogenetic comparison of influenza A(H3N2) haemagglutinin genes, EU/EEA, weeks 40/2022–39/2023 (n = 3,240)
Figure 4
Figure 4
Phylogenetic comparison of influenza B/Victoria-lineage haemagglutinin gene, EU/EEA, weeks 40/2022–39/2023 (n = 2,116)
See this image and copyright information in PMC

References

    1. European Centre for Disease Prevention and Control (ECDC). European Respiratory Virus Surveillance Summary (ERVISS). Stockholm: ECDC. [Accessed: 24 Nov 2023]. Available from: https://erviss.org
    1. European Centre for Disease Prevention and Control. Reporting Protocol for integrated respiratory virus surveillance, version 1.3. Stockholm: ECDC; 2023. Available from: https://www.ecdc.europa.eu/en/publications-data/reporting-protocol-integ...
    1. Adlhoch C, Mook P, Lamb F, Ferland L, Melidou A, Amato-Gauci AJ, et al. Very little influenza in the WHO European Region during the 2020/21 season, weeks 40 2020 to 8 2021. Euro Surveill. 2021;26(11):2100221. 10.2807/1560-7917.ES.2021.26.11.2100221 - DOI - PMC - PubMed
    1. Adlhoch C, Mook P, Lamb F, Ferland L, Melidou A, Amato-Gauci AJ, et al. Very little influenza in the WHO European Region during the 2020/21 season, weeks 40 2020 to 8 2021. Euro Surveill. 2021;26(11):2100221. 10.2807/1560-7917.ES.2021.26.11.2100221 - DOI - PMC - PubMed
    1. Melidou A, Hungnes O, Pereyaslov D, Adlhoch C, Segaloff H, Robesyn E, et al. Predominance of influenza virus A(H3N2) 3C.2a1b and A(H1N1)pdm09 6B.1A5A genetic subclades in the WHO European Region, 2018-2019. Vaccine. 2020;38(35):5707-17. 10.1016/j.vaccine.2020.06.031 - DOI - PubMed

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