Towards the eradication of hepatitis B in Taiwan.

Viral hepatitides are important public health problems in humans. The etiologic agents were not identified until 1965, when Baruch S. Blumberg found the relationship of Australia antigen to serum hepatitis. The antigen was found to be the surface antigen of the hepatitis B virus (HBV). This observation launched a new era in the diagnosis, prevention and treatment of hepatitis B. Over 15-20 years, the natural history of HBV infection was elucidated, and more importantly, an effective vaccine became available. The routes of transmission were also made clear, rendering effective interruption of the transmission possible. The vaccine together with effective interruption of the transmission contributed greatly to the control of HBV infection. However, these measures do very little for those who have already been chronically infected. Fortunately, specific therapies against chronic hepatitis B started to appear about 10-15 years before, and the treatments have improved substantially in the last few years. Although far from perfect, effective means to treat those who are chronically infected now exist. In Taiwan, acute and chronic liver diseases were rampant as early as the beginning of the last century. Studies around 1975, showed an extremely high prevalence of chronic hepatitis B infection in the general population (15-20%), and 80-90% of the chronic liver diseases and hepatocellular carcinoma were caused by chronic infection with the HBV. This important health problem caught the attention of the government in the late 1970s, and a government-sponsored control program was finalized in 1981. Accordingly, a mass vaccination program against hepatitis B, primarily aiming at immunizing newborn infants, was launched on July 1, 1984. Twenty years after implementation of the program, the hepatitis B carrier rate in children covered by the program decreased by 85%, from ∼ 15% to <1%. Most importantly, the deadly sequela of hepatocellular carcinoma in the vaccinees was also found to decrease in parallel. This is the first time that a human cancer was prevented by vaccination. Despite the success, there are still some who were born after implementation of the program but were not prevented from developing chronic hepatitis B infection and hepatocellular carcinoma. Non-compliance to the vaccination schedule, breakthrough infection and intrauterine infection are the causes of the failure. At present, we have effective measures for immunizing susceptible individuals, interrupting the routes of transmission and treating the chronically infected. The time for considering the elimination or even the eradication of HBV infection has come. This is especially true for countries where hepatitis B infection is not endemic. Nevertheless, with the admirable results achieved in the past, Taiwan should also think about elimination/eradication of hepatitis B, even though it will certainly be much more difficult than in the non-endemic countries. In exploring the possibility of eliminating/eradicating hepatitis B in Taiwan, we reviewed the epidemiology of hepatitis B, and analyzed the problems that remain to be tackled in Taiwan. We hope that Taiwan can take further steps towards the elimination or eradication of hepatitis B.