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Abstract

Genomic surveillance during an influenza surge between November and early December 2025 at a university health clinic in the United States identified A(H3N2) subclade K (J.2.4.1) viruses with shared haemagglutinin amino acid substitutions in antigenic sites and the receptor-binding domain. An epitope-based model indicated reduced vaccine protection (mean predicted protection 0.13). Phylodynamic analyses suggested multiple introductions with onward campus-to-community spread, highlighting that universities and other semi-closed settings can amplify transmission and aid early characterisation of emerging lineages.

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/content/10.2807/1560-7917.ES.2026.31.7.2600111
2026-02-19
2026-03-15
/content/10.2807/1560-7917.ES.2026.31.7.2600111
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Influenza A(H3N2) subclade K (J.2.4.1) viruses associated with a surge at a university health clinic, Arizona, the United States, November to early December 2025
<p class="citation"> <span>Citation style for this article:</span> <span class="meta-value authors"> <a href="/search?value1=Matthew+Scotch&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Scotch Matthew</a>, <a href="/search?value1=Temitope+OC+Faleye&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Faleye Temitope OC</a>, <a href="/search?value1=Angelica+Urquidez-Negrete&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Urquidez-Negrete Angelica</a>, <a href="/search?value1=Bradley+Bobbett&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Bobbett Bradley</a>, <a href="/search?value1=Veronica+Boyle&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Boyle Veronica</a>, <a href="/search?value1=Kelly+Conard&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Conard Kelly</a>, <a href="/search?value1=Lucy+Sublasky-Rodriguez&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Sublasky-Rodriguez Lucy</a>, <a href="/search?value1=Vel+Murugan&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Murugan Vel</a></span>. Influenza A(H3N2) subclade K (J.2.4.1) viruses associated with a surge at a university health clinic, Arizona, the United States, November to early December 2025. <a href="/content/ecdc">Euro Surveill.</a> 2026;31(7):pii=2600111. <a href="https://doi.org/10.2807/1560-7917.ES.2026.31.7.2600111" title="doi link" target="_blank">https://doi.org/10.2807/1560-7917.ES.2026.31.7.2600111</a> <span class="ES_Article_citation"> <span class="generated">Received</span>: 06 Feb 2026;&nbsp;&nbsp; <span class="generated">Accepted</span>: 18 Feb 2026 </span> </p>
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