2023/24 mid-season influenza and Omicron XBB.1.5 vaccine effectiveness estimates from the Canadian Sentinel Practitioner Surveillance Network (SPSN).
Skowronski DM., Zhan Y., Kaweski SE., Sabaiduc S., Khalid A., Olsha R., Carazo S., Dickinson JA., Mather RG., Charest H., Jassem AN., Levade I., Hasso M., Zelyas N., Gao R., Bastien N.
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).