Epidemiological transition of hepatitis A in India: issues for vaccination in developing countries.

With improvement in economic and living conditions of the communities, the age of acquiring hepatitis A virus (HAV) infection is shifting from early childhood to adolescence and young adulthood. Such epidemiological shift leads to an increased incidence of symptomatic HAV infection, including heightened risk of liver failure. Data from India indicate that the population is no longer homogeneous for its HAV exposure profile. Occasional outbreaks of HAV and higher proportions of symptomatic cases are reported amongst older children and adults from different regions of the country. However, the heterogeneous exposure to HAV defies widespread use of the vaccine. The challenge is to recognize the susceptible pockets and take pre-emptive steps. In regions with rapid improvement in living standards and environmental hygiene, there is a need for regular surveillance through structured protocols that are able to identify early signs of epidemiological shift. This review discusses relevant issues and concerns to influence decision making for HAV vaccination in such transition societies.