Immunisation against hepatitis B in Taiwan.

Hepatitis B is hyperendemic in Taiwan; more than 15% of adults are chronic carriers of the virus and longterm sequelae (chronic active hepatitis, cirrhosis, and hepatocellular carcinoma) are common. A national immunisation programme was implemented in 1984 to tackle the problem. This entailed immunisation of newborn children, followed by susceptible school children and young adults. The programme, which has been in place for a decade, has resulted in a pronounced reduction in the prevalence of HBsAg among young children and seems to have led to a reduction in horizontal transmission among older children.