<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Eeva K Broberg</style></author><author><style face="normal" font="default" size="100%">Maja Vukovikj</style></author><author><style face="normal" font="default" size="100%">Olov Svartström</style></author><author><style face="normal" font="default" size="100%">Iris Hasibra</style></author><author><style face="normal" font="default" size="100%">Maximilian Riess</style></author><author><style face="normal" font="default" size="100%">Melidou, Angeliki</style></author></authors><tertiary-authors><author><style face="normal" font="default" size="100%">Sarah Denayer</style></author><author><style face="normal" font="default" size="100%">François Dufrasne</style></author><author><style face="normal" font="default" size="100%">Anna Parys</style></author></tertiary-authors><translated-authors><author><style face="normal" font="default" size="100%">Members of the ERLI-Net network</style></author></translated-authors></contributors><titles><title><style face="normal" font="default" size="100%">Antigenic changes in influenza A(H3N2) driven by genetic evolution: Insights from virological surveillance, EU/EEA, week 40/2023 to week 9/2024</style></title><secondary-title><style face="normal" font="default" size="100%">Eurosurveillance</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">2023/24 influenza season</style></keyword><keyword><style  face="normal" font="default" size="100%">Europe</style></keyword><keyword><style  face="normal" font="default" size="100%">Influenza H3N2</style></keyword><keyword><style  face="normal" font="default" size="100%">influenza virus vaccine</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2024</style></year><pub-dates><date><style  face="normal" font="default" size="100%">Dec-12-2024</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">29</style></volume><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;&lt;strong&gt;Background&lt;/strong&gt;&lt;/p&gt;

&lt;p&gt;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.&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;Aim&lt;/strong&gt;&lt;/p&gt;

&lt;p&gt;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.&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;Methods&lt;/strong&gt;&lt;/p&gt;

&lt;p&gt;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.&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;Results&lt;/strong&gt;&lt;/p&gt;

&lt;p&gt;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.&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;Conclusion&lt;/strong&gt;&lt;/p&gt;

&lt;p&gt;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.&lt;/p&gt;
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