Impact and effectiveness of childhood varicella vaccine program in Queensland, Australia
Sarah L Sheridan1, Helen E Quinn2, Brynley P Hull3
1School of Public Health, The University of Queensland, Herston, QLD 4006, Australia.
Insights
Australia's single-dose varicella vaccination program significantly reduced chickenpox hospitalizations by over 70%. The varicella vaccine shows high effectiveness against hospitalization but moderate effectiveness against emergency department visits.
Area of Science:
- Public Health
- Vaccinology
- Epidemiology
Background:
- Australia implemented a universal, single-dose varicella vaccination program for children in November 2005.
- This study assesses the program's impact on varicella-related hospitalizations in Queensland.
Purpose of the Study:
- To evaluate the effectiveness of the single-dose varicella vaccine in Australia.
- To analyze trends in varicella hospitalizations before and after the public funding of the vaccine.
Main Methods:
- Age-standardized hospitalization rates were calculated for 2000-2014.
- Case-control studies assessed the association between vaccination and varicella hospitalizations or emergency department presentations.
- Vaccine effectiveness was determined using odds ratios.
Main Results:
- Varicella hospitalizations decreased by over 70% in 2011-2014 compared to 2000-2003.
- Single-dose varicella vaccine effectiveness was 81.9% against principal diagnosis of varicella hospitalization.
- Effectiveness was 57.9% against emergency department presentations for varicella.
Conclusions:
- The Australian single-dose varicella vaccination program has substantially reduced varicella-related illness.
- The vaccine is highly effective against hospitalization but moderately effective against emergency department visits.
Background:
In November 2005, Australia introduced a publicly funded single dose of varicella vaccine for children aged 18-months. We describe the impact of this program on varicella hospitalisations in Queensland and provide the first assessment of single-dose varicella vaccine effectiveness in Australia since the program commenced.
Methods:
Age-standardised varicella hospitalisation rates were calculated for 2000-2014 and pre- and post-public funding period rates compared. Case-control studies were conducted to investigate the association between vaccine receipt and both varicella hospitalisations and uncomplicated varicella emergency department presentations. Cases were matched to controls from a population-based register by date of birth and state of residence. Vaccine effectiveness was calculated as (1-odds ratio)×100%.
Results:
Compared to the pre-funded period (2000-2003), age-standardised varicella hospitalisation rates declined by more than 70% in 2011-2014 with varicella principal diagnosis rates declining from 5.7 to 1.6 per 100,000 population per year. Varicella vaccine effectiveness at preventing hospitalisation with a principal diagnosis of varicella among children aged 19-months to 6-years was 81.9% (95% confidence interval: 61.8-91.4%), while for emergency department presentations among children aged 19-months to 8-years it was 57.9% (95% confidence interval: 48.5-65.5%).
Conclusions:
In Australia, the single-dose varicella vaccination program has substantially reduced varicella morbidity. The single-dose varicella vaccine schedule is moderately-to-highly effective against hospitalisation, but appears less effective against emergency department presentations.
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