Hepatitis A is an acute, usually self-limiting disease of the liver caused by hepatitis A virus (HAV). HAV is transmitted from person to person, primarily by the faecal-oral route. The incidence of hepatitis A is closely related to socioeconomic development, and sero-epidemiological studies show that prevalence of anti-HAV antibodies in the general population varies from 15% to close to 100% in different parts of the world. An estimated 1.5 million clinical cases of hepatitis A occur each year. In young children HAV infection is usually asymptomatic whereas symptomatic disease occurs more commonly among adults. Infection with HAV induces lifelong immunity. In areas of low endemicity, hepatitis A usually occurs as single cases among persons in high-risk groups or as outbreaks involving a small number of persons. In areas of high endemicity most persons are infected with HAV without symptoms during childhood. This explains why clinical hepatitis A is uncommon. In countries of low and intermediate disease endemicity, adult disease is seen more often. Hepatitis A may represent a substantial medical and economic burden. Currently, four inactivated vaccines against HAV are internationally available. All four vaccines are safe and effective, with long-lasting protection. None of the vaccines are licensed for children less than one year of age.

The results of appropriate epidemiological and cost-benefit studies should be carefully considered before deciding on national policies concerning immunization against hepatitis A. As part of this decision process, the public health impact of hepatitis A should be weighed against the impact of other vaccine-preventable infections, including diseases caused by hepatitis B, Haemophilus influenzae type b, rubella and yellow fever.

In countries highly endemic for hepatitis A, almost all persons are infected in childhood with the virus without showing symptoms, effectively preventing clinical hepatitis A in adolescents and adults. In these countries, large-scale vaccination programmes are not recommended. In countries of intermediate disease endemicity, where a relatively large proportion of the adult population is susceptible to HAV, and where hepatitis A represents a significant public health burden, large-scale childhood vaccination may be considered as a supplement to health education and improved sanitation.

In regions of low disease endemicity, vaccination against hepatitis A is indicated for individuals with increased risk of contracting the infection, such as travellers to areas of intermediate or high endemicity.