A community-wide hepatitis A outbreak in the Shoalhaven region, New South Wales

We investigated a community-wide outbreak of hepatitis A virus infection in the Shoalhaven region of the New South Wales south coast. Epidemiological features of the outbreak suggested that transmission was predominantly person-to-person. These included: the prolonged course of the epidemic, the bimodal age-specific attack rate, the lower socioeconomic risk groups affected, and the large proportion of cases who reported prior contact with another case. Although widespread use of post-exposure immunoprophylaxis appeared to be effective in preventing symptomatic infection in individuals, it did not rapidly halt the outbreak. We review methods of mass intervention for community-wide outbreaks of hepatitis A virus infection, and define priorities for investigation of future outbreaks.