Impact of the national targeted Hepatitis A immunisation program in Australia: 2000-2014

Abstract

In November 2005, hepatitis A vaccine was funded under the Australian National Immunisation Program for Aboriginal and Torres Strait Islander (Indigenous) children aged 12–24 months in the targeted jurisdictions of Queensland, South Australia, Western Australia and the Northern Territory.

We reviewed the epidemiology of hepatitis A from 2000 to 2014 using data from the Australian National Notifiable Diseases Surveillance System, the National Hospital Morbidity Database, and Australian Bureau of Statistics causes-of-death data. The impact of the national hepatitis A immunisation program was assessed by comparison of pre-vaccine (2000–2005) and post-vaccine time periods (2006–2014), by age group, Indigenous status and jurisdiction using incidence rate ratios (IRR) per 100,000 population and 95% confidence intervals (CI).

The national pre-vaccine notification rate in Indigenous people was four times higher than the non-Indigenous rate, and declined from 8.41 per 100,000 (95% CI 5.03–11.79) pre-vaccine to 0.85 per 100,000 (95% CI 0.00–1.99) post-vaccine, becoming similar to the non-Indigenous rate. Notification and hospitalisation rates in Indigenous children aged <5 years from targeted jurisdictions declined in the post-vaccine period when compared to the pre-vaccine period (notifications: IRR = 0.07; 95% CI 0.04–0.13; hospitalisations: IRR = 0.04; 95% CI 0.01–0.16). As did notification rates in Indigenous people aged 5–19 (IRR = 0.08; 95% CI 0.05–0.13) and 20–49 years (IRR = 0.06; 95% CI 0.02–0.15) in targeted jurisdictions. For non-Indigenous people from targeted jurisdictions, notification rates decreased significantly in children aged <5 years (IRR 0.47; 95% CI 0.31–0.71), and significantly more overall (IRR = 0.43; 95% CI 0.39–0.47) compared to non-Indigenous people from non-targeted jurisdictions (IRR = 0.60; 95% CI 0.56–0.64).

The national hepatitis A immunisation program has had a significant impact in the targeted population with relatively modest vaccine coverage, with evidence suggestive of substantial herd protection effects. Keywords

Indigenous; Vaccination; Targeted; Epidemiology; Notification; Hepatitis A