Australia’s active hospital-based surveillance for severe childhood disease
A new Australian surveillance study shows that influenza vaccination is effective in protecting children across all age groups – including those with and without underlying medical conditions – from influenza-related hospitalisation.
Researchers analysed 8,762 laboratory-confirmed influenza hospitalisations in children aged less than 16 years across Australia, using data collected by the Paediatric Active Enhanced Disease Surveillance and Influenza Complications Alert Network (PAEDS-FluCAN) over a 6-year period from 2019 to 2024.
Using a test-negative study design that included 10,955 influenza-test-negative controls, overall influenza vaccine effectiveness was estimated to be 65.6% against hospital admission – meaning that the risk of influenza-related hospitalisation was reduced by almost two-thirds in vaccinated children.
Vaccine effectiveness varied across influenza seasons and virus strains, ranging from 56.3% in 2019 to 82.5% in 2023, and 51.6% for A/H3N2 strains to 79.3% for A/H1N1 strains.
Reassuringly, the protective effect of influenza vaccination extended to children with chronic medical conditions, who are known to be at higher risk of severe influenza outcomes, as well as to previously healthy children, who continue to account for a substantial proportion of severe cases.
Despite this evidence that childhood influenza vaccination is effective in preventing hospitalisations, influenza vaccine uptake has dropped sharply since the COVID-19 pandemic. Estimated coverage among vaccine-eligible children admitted to hospital with acute respiratory illness fell from 44% in 2019 to just 19.6% in 2022, with only small improvements seen in 2023 (23%) and 2024 (26%).
This decline in coverage was observed across every state and territory, in all age groups, and among children with medical risk factors, despite influenza vaccination being available free of charge for eligible children under the National Immunisation Program or via state- and territory-funded programs.
Influenza continues to place a significant burden on Australian hospitals. Among children admitted with influenza-related illness, 7.1% of require intensive care, and influenza-related paediatric deaths have been recorded every year since influenza circulation resumed following the COVID-19 pandemic.
The authors noted that many of these severe outcomes were potentially preventable through vaccination and said the findings highlight the urgent need to rebuild confidence in influenza vaccination for children.
Vaccination remains a strong and reliable tool for preventing influenza-related hospitalisation. Improving coverage is critical to reducing avoidable severe disease in children, the study concluded.
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