Seroepidemiology of hepatitis B virus infection in children - Ten years of mass vaccination in Taiwan

Objective.-To study the seroepidemiology of hepatitis B virus (HBV) infection in children 10 years after a mass hepatitis B vaccination program was begun in Taiwan. Design.-Cross-sectional seroprevalence survey. Setting.-Cheng-Chung/Chung-Cheng District, Taipei, Taiwan, 1994. Subjects and Methods.-Serum samples from 1515 healthy children younger than 12 years were tested for HBV markers. The results were compared with a baseline seroepidemiologic study conducted just before the vaccination program was launched in 1984 and with a subsequent study in 1989 in the same area. Main Results.-Eighty-seven percent of the children had received at least 3 doses of HBV vaccine. The overall prevalence rate of hepatitis B surface antigenemia decreased from 9.8% in 1984 to 1.3% in 1994. A statistically significant decrease was observed in every age group from 1 to 10 years. The overall prevalence rate of hepatitis B core antibody was 26% in 1984, 15% in 1989, and 4.0% in 1994. This suggests that the risk of horizontal HBV infection has decreased overtime, not only because of the protective effect of the vaccine but also because the infection source has diminished. A high prevalence rate of hepatitis B surface antibody (79%) was noted in 1994 as anticipated. Conclusions.-The Taiwanese mass vaccination program has protected most children younger than 10 years from becoming carriers, reducing both perinatal and horizontal HBV transmission. Mass HBV vaccination has proved to be a successful method to control HBV infection in this hyperendemic area.