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. 2022 Apr;27(15):2200278.
doi: 10.2807/1560-7917.ES.2022.27.15.2200278.

A late sharp increase in influenza detections and low interim vaccine effectiveness against the circulating A(H3N2) strain, Denmark, 2021/22 influenza season up to 25 March 2022

Hanne-Dorthe Emborg  1 , Lasse S Vestergaard  1 , Amanda Bolt Botnen  1 , Jens Nielsen  1 , Tyra G Krause  1 , Ramona Trebbien  1
Affiliations

A late sharp increase in influenza detections and low interim vaccine effectiveness against the circulating A(H3N2) strain, Denmark, 2021/22 influenza season up to 25 March 2022

Hanne-Dorthe Emborg et al. Euro Surveill. 2022 Apr.

Abstract

We estimated interim influenza A vaccine effectiveness (VE) following a late sharp rise in cases during an influenza A(H3N2)-dominated 2021/22 season, after lifting COVID-19 restrictions. In children aged 2-6 years offered a live attenuated influenza vaccine, adjusted VE was 62.7% (95% CI: 10.9-84.4) in hospitalised and 64.2% (95% CI: 50.5-74.1) in non-hospitalised children. In non-hospitalised patients aged 7-44 years, VE was 24.8% (95% CI: 12.8-35.2); VE was non-significant in remaining age groups and hospital/non-hospital settings.

Keywords: 2021/22 influenza season; Influenza A(H3N2); Vaccine effectiveness.

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Conflict of interest statement

Conflict of interest: None declared.

Figures

Figure
Figure
A. Number of patients testing positive for influenza A and B and percentage positive tests, B. number of new patients admitted to hospital with influenza and C. total number of patients tested for influenza by week, Denmark, week 40 2019–week 12 2022
See this image and copyright information in PMC

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