End of 2022/23 season influenza vaccine effectiveness in primary care in Great Britain

Whitaker, Heather J. and Willam, Naoma and Cottrell, Simon and Goudie, Rosalind and Andrews, Nick and Evans, Josie and Moore, Catherine and Agrawal, Utkarsh and Hassell, Katie and Gunson, Rory and Zitha, Jana and Anand, Sneha and Sebastian‐Pillai, Praveen and Kalapotharakou, Panoraia and Okusi, Cecilia and Hoschler, Katja and Jamie, Gavin and Kele, Beatrix and Hamilton, Mark and Couzens, Anastasia and Quinot, Catherine and Pheasant, Kathleen and Byford, Rachel and Marsh, Kimberly and Robertson, Chris and de Lusignan, Simon and Williams, Christopher and Zambon, Maria and McMenamin, Jim and Watson, Conall H. (2024) End of 2022/23 season influenza vaccine effectiveness in primary care in Great Britain. Influenza and Other Respiratory Viruses, 18 (5). e13295. ISSN 1750-2640 (https://doi.org/10.1111/irv.13295)

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Background: The 2022/23 influenza season in the United Kingdom saw the return of influenza to prepandemic levels following two seasons with low influenza activity. The early season was dominated by A(H3N2), with cocirculation of A(H1N1), reaching a peak late December 2022, while influenza B circulated at low levels during the latter part of the season. From September to March 2022/23, influenza vaccines were offered, free of charge, to all aged 2–13 (and 14–15 in Scotland and Wales), adults up to 49 years of age with clinical risk conditions and adults aged 50 and above across the mainland United Kingdom. Methods: End-of-season adjusted vaccine effectiveness (VE) estimates against sentinel primary-care attendance for influenza-like illness, where influenza infection was laboratory confirmed, were calculated using the test negative design, adjusting for potential confounders. Methods: Results In the mainland United Kingdom, end-of-season VE against all laboratory-confirmed influenza for all those > 65 years of age, most of whom received adjuvanted quadrivalent vaccines, was 30% (95% CI: −6% to 54%). VE for those aged 18–64, who largely received cell-based vaccines, was 47% (95% CI: 37%–56%). Overall VE for 2–17 year olds, predominantly receiving live attenuated vaccines, was 66% (95% CI: 53%–76%). Conclusion: The paper provides evidence of moderate influenza VE in 2022/23.