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. 2023 Feb;28(5):2300043.
doi: 10.2807/1560-7917.ES.2023.28.5.2300043.

Vaccine effectiveness estimates from an early-season influenza A(H3N2) epidemic, including unique genetic diversity with reassortment, Canada, 2022/23

Danuta M Skowronski  1   2 , Erica Sy Chuang  2 , Suzana Sabaiduc  2 , Samantha E Kaweski  2 , Shinhye Kim  2 , James A Dickinson  3 , Romy Olsha  4 , Jonathan B Gubbay  5   4 , Nathan Zelyas  6 , Hugues Charest  7 , Nathalie Bastien  8 , Agatha N Jassem  1   2 , Gaston De Serres  9   10   7
Affiliations

Vaccine effectiveness estimates from an early-season influenza A(H3N2) epidemic, including unique genetic diversity with reassortment, Canada, 2022/23

Danuta M Skowronski et al. Euro Surveill. 2023 Feb.

Abstract

The Canadian Sentinel Practitioner Surveillance Network estimated vaccine effectiveness (VE) during the unusually early 2022/23 influenza A(H3N2) epidemic. Like vaccine, circulating viruses were clade 3C.2a1b.2a.2, but with genetic diversity affecting haemagglutinin positions 135 and 156, and reassortment such that H156 viruses acquired neuraminidase from clade 3C.2a1b.1a. Vaccine provided substantial protection with A(H3N2) VE of 54% (95% CI: 38 to 66) overall. VE was similar against H156 and vaccine-like S156 viruses, but with potential variation based on diversity at position 135.

Keywords: A(H3N2); Influenza; clade; imprinting; observational study; reassortment; test-negative design; vaccine effectiveness.

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Conflict of interest statement

Conflict of interest: DMS is Principal Investigator on grants received to her institution from the Public Health Agency of Canada and the BCCDC Foundation for Public Health in support of this work. She has received grants from the Canadian Institutes of Health Research and the Michael Smith Foundation for Health Research for unrelated work, also paid to her institution. JBG is a paid consultant scientific editor for GIDEON Informatics, Inc., which is unrelated to the current work. Other authors have no conflicts of interest to declare.

Figures

Figure 1
Figure 1
Influenza detections among eligible patients presenting with influenza-like illness, by week of specimen collection, SPSN, Canada, 1 November 2022–6 January 2023 (weeks 44–1) (n = 1,490)
Figure 2
Figure 2
Distribution of clade 3C.2a1b.2a2 variants among genetically characterised influenza A(H3N2) viruses contributing to influenza vaccine effectiveness analyses, SPSN, Canada, 1 November–28 December 2022 (weeks 44–1) (n = 391)
See this image and copyright information in PMC

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