Influenza vaccine effectiveness against hospitalizations associated with influenza A(H3N2) in Hong Kong children aged 9 months to 17 years, June-November 2023

Caitriona Murphy; Mike Y W Kwan; Eunice L Y Chan; Joshua S C Wong; Sheena G Sullivan; Malik Peiris; Benjamin J Cowling; So-Lun Lee

doi:10.1016/j.vaccine.2024.02.056

Influenza vaccine effectiveness against hospitalizations associated with influenza A(H3N2) in Hong Kong children aged 9 months to 17 years, June-November 2023

Vaccine. 2024 Mar 19;42(8):1878-1882. doi: 10.1016/j.vaccine.2024.02.056. Epub 2024 Feb 22.

Authors

Caitriona Murphy¹, Mike Y W Kwan², Eunice L Y Chan³, Joshua S C Wong², Sheena G Sullivan⁴, Malik Peiris⁵, Benjamin J Cowling⁶, So-Lun Lee⁷

Affiliations

¹ WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China.
² Department of Paediatrics and Adolescent Medicine, Princess Margaret Hospital, Hong Kong Special Administrative Region, China.
³ Department of Paediatrics and Adolescent Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China.
⁴ WHO Collaborating Centre for Reference and Research on Influenza, Royal Melbourne Hospital, and Department of Infectious Diseases, University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia; Department of Epidemiology, University of California, Los Angeles, California.
⁵ WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China; Centre for Immunology & Infection, Hong Kong Science and Technology Park, New Territories, Hong Kong Special Administrative Region, China.
⁶ WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China; Laboratory of Data Discovery for Health Limited, Hong Kong Science and Technology Park, New Territories, Hong Kong Special Administrative Region, China. Electronic address: bcowling@hku.hk.
⁷ Department of Paediatrics and Adolescent Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China; Department of Paediatrics and Adolescent Medicine, Queen Mary Hospital, Hong Kong Special Administrative Region.

PMID: 38395722
PMCID: PMC10947845 (available on 2025-03-19)
DOI: 10.1016/j.vaccine.2024.02.056

Abstract

A test negative study was carried out from 13 June through to 15 November 2023 enrolling 3183 children hospitalized with acute respiratory illness in Hong Kong. Influenza A and B viruses were detected in 528 (16.6%) children, among which 419 (79.4%) were influenza A(H3N2). The overall vaccine effectiveness against hospitalization associated with any influenza virus infection was estimated as 22.4% (95% CI: -11.7%, 46.1%), and against influenza A(H3N2) specifically was 14.3% (95% CI: -29.2%, 43.2%). Despite the moderate to low VE estimated here, which could be a result of waning immunity and antigenic drift, influenza vaccination remains an important approach to reduce the impact of influenza in children.

Keywords: H3N2; Influenza; Vaccination; Vaccine effectiveness.

MeSH terms

Child
Hong Kong / epidemiology
Hospitalization
Humans
Influenza A Virus, H3N2 Subtype
Influenza Vaccines*
Influenza, Human* / epidemiology
Influenza, Human* / prevention & control
Seasons
Vaccination
Vaccine Efficacy

Substances

Influenza Vaccines

Grants and funding

75N93021C00015/AI/NIAID NIH HHS/United States