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Abstract

The Canadian Sentinel Practitioner Surveillance Network (SPSN) reports interim 2024/25 vaccine effectiveness (VE) against acute respiratory illness due to laboratory-confirmed influenza during a delayed season of predominant A(H1N1)pdm09 and lower A(H3N2) co-circulation. Through mid-January, the risk of outpatient illness due to influenza A is reduced by about half among vaccinated vs unvaccinated individuals. Adjusted VE is 53% (95% CI: 36–65) against A(H1N1)pdm09, comprised of clades 5a.2a and 5a.2a.1, and 54% (95% CI: 29–70) against A(H3N2), virtually all clade 2a.3a.1.

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/content/10.2807/1560-7917.ES.2025.30.4.2500059
2025-01-30
2025-01-31
/content/10.2807/1560-7917.ES.2025.30.4.2500059
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Interim estimates of vaccine effectiveness against influenza A(H1N1)pdm09 and A(H3N2) during a delayed influenza season, Canada, 2024/25
<p class="citation"> <span>Citation style for this article:</span> <span class="meta-value authors"> <a href="/search?value1=Lea+Separovic&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Separovic Lea</a>, <a href="/search?value1=Yuping+Zhan&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Zhan Yuping</a>, <a href="/search?value1=Samantha+E+Kaweski&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Kaweski Samantha E</a>, <a href="/search?value1=Suzana+Sabaiduc&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Sabaiduc Suzana</a>, <a href="/search?value1=Sara+Carazo&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Carazo Sara</a>, <a href="/search?value1=Romy+Olsha&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Olsha Romy</a>, <a href="/search?value1=Richard+G+Mather&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Mather Richard G</a>, <a href="/search?value1=James+A+Dickinson&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Dickinson James A</a>, <a href="/search?value1=Maan+Hasso&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Hasso Maan</a>, <a href="/search?value1=Isabelle+Meunier&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Meunier Isabelle</a>, <a href="/search?value1=Agatha+N+Jassem&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Jassem Agatha N</a>, <a href="/search?value1=Nathan+Zelyas&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Zelyas Nathan</a>, <a href="/search?value1=Ruimin+Gao&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Gao Ruimin</a>, <a href="/search?value1=Nathalie+Bastien&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Bastien Nathalie</a>, <a href="/search?value1=Danuta+M+Skowronski&option1=author&noRedirect=true" class="nonDisambigAuthorLink">Skowronski Danuta M</a></span>. Interim estimates of vaccine effectiveness against influenza A(H1N1)pdm09 and A(H3N2) during a delayed influenza season, Canada, 2024/25. <a href="/content/ecdc">Euro Surveill.</a> 2025;30(4):pii=2500059. <a href="https://doi.org/10.2807/1560-7917.ES.2025.30.4.2500059" title="doi link" target="_blank">https://doi.org/10.2807/1560-7917.ES.2025.30.4.2500059</a> <span class="ES_Article_citation"> <span class="generated">Received</span>: 20 Jan 2025;&nbsp;&nbsp; <span class="generated">Accepted</span>: 29 Jan 2025 </span> </p>
/content/10.2807/1560-7917.ES.2025.30.4.2500059
/content/10.2807/1560-7917.ES.2025.30.4.2500059
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