Eurosurv. 2023/24 mid-season influenza and Omicron XBB.1.5 vaccine effectiveness estimates from the Canadian Sentinel Practitioner Surveillance Netwo

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• Danuta M Skowronski[SUP]1,2[/SUP] , Yuping Zhan[SUP]1[/SUP] , Samantha E Kaweski[SUP]1[/SUP] , Suzana Sabaiduc[SUP]1[/SUP] , Ayisha Khalid[SUP]1[/SUP] , Romy Olsha[SUP]3[/SUP] , Sara Carazo[SUP]4[/SUP] , James A Dickinson[SUP]5[/SUP] , Richard G Mather[SUP]3,6[/SUP] , Hugues Charest[SUP]4[/SUP] , Agatha N Jassem[SUP]1[/SUP] , Inès Levade[SUP]4[/SUP] , Maan Hasso[SUP]3[/SUP] , Nathan Zelyas[SUP]7[/SUP] , Ruimin Gao[SUP]8[/SUP] , Nathalie Bastien[SUP]8[/SUP]

The Canadian Sentinel Practitioner Surveillance Network reports mid-season 2023/24 influenza vaccine effectiveness (VE) of 63% (95% CI: 51–72) against influenza A(H1N1)pdm09, lower for clade 5a.2a.1 (56%; 95% CI: 33–71) than clade 5a.2a (67%; 95% CI: 48–80), and lowest against influenza A(H3N2) (40%; 95% CI: 5–61). The Omicron XBB.1.5 vaccine protected comparably well, with VE of 47% (95% CI: 21–65) against medically attended COVID-19, higher among people reporting a prior confirmed SARS-CoV-2 infection at 67% (95% CI: 28–85).

https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2024.29.7.2400076
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