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Abstract

Understanding population immunity to emerging viruses is critical for risk assessment. We characterised antibody responses to avian influenza A(H9N2) viruses in 298 human sera from adults in New York City. We observed widespread cross-reactive H9-binding antibodies, albeit at lower levels (GMT = 371.3) than against seasonal H3 (GMT = 1,398.0), with low to undetectable haemagglutination inhibition and neutralising antibodies. In contrast, NA-binding and neuraminidase inhibition responses were moderate (GMT = 149.5 and 34.2) and comparable to those against human seasonal N2 (GMT = 259.0 and 42.2).

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/content/10.2807/1560-7917.ES.2026.31.20.2600375
2026-05-21
2026-06-10
/content/10.2807/1560-7917.ES.2026.31.20.2600375
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Cross-reactive human antibody responses to H9N2 influenza virus, New York, United States, 2025
<p class="citation"> <span>Citation style for this article:</span> <span class="meta-value authors"> <a href="/search?value1=Gagandeep+Singh&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Singh Gagandeep</a>, <a href="/search?value1=Disha+Bhavsar&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Bhavsar Disha</a>, <a href="/search?value1=Lucas+M+Ferreri&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Ferreri Lucas M</a>, <a href="/search?value1=Jessica+R+Nardulli&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Nardulli Jessica R</a>, <a href="/search?value1=Charles+Gleason&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Gleason Charles</a>, <a href="/search?value1=Neko+Lyttle&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Lyttle Neko</a>, <a href="/search?value1=Yuexing+Chen&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Chen Yuexing</a>, <a href="/search?value1=Anice+C+Lowen&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Lowen Anice C</a>, <a href="/search?value1=Viviana+Simon&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Simon Viviana</a>, <a href="/search?value1=Florian+Krammer&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Krammer Florian</a></span>. Cross-reactive human antibody responses to H9N2 influenza virus, New York, United States, 2025. <a href="/content/ecdc">Euro Surveill.</a> 2026;31(20):pii=2600375. <a href="https://doi.org/10.2807/1560-7917.ES.2026.31.20.2600375" title="doi link" target="_blank">https://doi.org/10.2807/1560-7917.ES.2026.31.20.2600375</a> <span class="ES_Article_citation"> <span class="generated">Received</span>: 06 May 2026;&nbsp;&nbsp; <span class="generated">Accepted</span>: 21 May 2026 </span> </p>
/content/10.2807/1560-7917.ES.2026.31.20.2600375
/content/10.2807/1560-7917.ES.2026.31.20.2600375
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