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

Authors:

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

Details:

Vaccine, Volume 42, Issue 8, 2024-03-19

Article Link: Click here

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.