Hepatitis A epidemiology in Australia: national seroprevalence and notifications

Objectives: To determine hepatitis A seroprevalence and notification rates in Australia in order to inform vaccination policy. Design: Seroprevalence was determined by cross-sectional survey of opportun istically collected sera; notifications were extracted from the National No tifiable Diseases Surveillance System. Participants: 3043 serum samples collected in 1998 were obtained from 46 la boratories around Australia. Sample size in each age group was based on exp ected seroprevalence, and States and Territories were sampled proportionall y to their population size. Males and females were equally represented. Not ifications were extracted for cases with onset between 1 January 1991 and 3 1 December 1998. Main outcome measures: Seroprevalence and notifications were analysed by ag e, sex and State/Territory. Results: 41.1% of serum samples were seropositive for hepatitis A (95% CI, 39.4%-42.9%) (population-weighted seroprevalence, 38.3%). Seroprevalence wa s significantly associated with increasing age (P<0.001), but did not diffe r between the sexes (male:female ratio, 1.04:1; 95% CI, 0.95-1.14). However , significantly more notifications were recorded for males than females (ma le:female ratio, 1.65:1; 95% CI, 1.60-1.70). The Northern Territory had the highest seroprevalence (68.8%; 95% CI, 52.7%-84.8%) and annual notificatio n rates (48.7 per 100 000 population; 95% CI, 45.0-52.4 per 100 000). Conclusions: These data show that about half the Australian population has not been exposed to hepatitis A and is therefore susceptible to infection. However, any decision on national routine childhood hepatitis A vaccination requires a cost-benefit analysis. Routine vaccination of high-incidence co mmunities remains controversial.