SEROEPIDEMIOLOGY OF HEPATITIS-B VIRUS-INFECTION IN CHILDREN - 10 YEARS OF MASS VACCINATION IN TAIWAN

Objective.-To study the seroepidemiology of hepatitis B virus (HBV) in fection in children 10 years after a mass hepatitis B vaccination prog ram was begun in Taiwan. Design.-Cross-sectional seroprevalence survey . Setting.-Cheng-Chung/Chung-Cheng District, Taipei, Taiwan, 1994. Sub jects and Methods.-Serum samples from 1515 healthy children younger th an 12 years were tested for HBV markers. The results were compared wit h a baseline seroepidemiologic study conducted just before the vaccina tion program was launched in 1984 and with a subsequent study in 1989 in the same area. Main Results.-Eighty-seven percent of the children h ad received at least 3 doses of HBV vaccine. The overall prevalence ra te of hepatitis B surface antigenemia decreased from 9.8% in 1984 to 1 .3% in 1994. A statistically significant decrease was observed in ever y age group from 1 to 10 years. The overall prevalence rate of hepatit is B core antibody was 26% in 1984, 15% in 1989, and 4.0% in 1994. Thi s suggests that the risk of horizontal HBV infection has decreased ove rtime, not only because of the protective effect of the vaccine but al so because the infection source has diminished. A high prevalence rate of hepatitis B surface antibody (79%) was noted in 1994 as anticipate d. Conclusions.-The Taiwanese mass vaccination program has protected m ost children younger than 10 years from becoming carriers, reducing bo th perinatal and horizontal HBV transmission. Mass HBV vaccination has proved to be a successful method to control HBV infection in this hyp erendemic area.