DURATION AND EFFICACY OF IMMUNE-RESPONSE TO HEPATITIS-B VACCINE IN HIGH-RISK CHINESE ADOLESCENTS

The long-term immunogenicity and protection provided by a plasma-derived hepatitis B vaccine was determined in a cohort of susceptible Chinese adolescents who were immunized in 1986. Ninety-five children, aged 13 to 15 years, received three vaccine doses (at 0, 1, and 2 months), and during subsequent annual follow-ups for 5 years, their serological markers for hepatitis B virus and levels of alanine aminotransferase were determined. After the primary vaccine series, 94 subjects (99%) developed antibody to hepatitis B surface antigen (anti-HBs). At the 60-month follow-up, 73% of vaccinees still had levels of antibody at or above 10 mIU/mL, which is considered the protective level. Nine vaccine responders (9%) developed antibody to hepatitis B core antigen, and in eight of these individuals, levels of anti-HBs increased transiently. None of the adolescents developed detectable levels of hepatitis B surface antigen or clinical hepatitis. Immunization of high-risk adolescents with a plasma-derived hepatitis B vaccine can induce long-lasting protective immunity that can prevent or modify primary infection for at least 5 years. Immunization with booster doses is not necessary during this period.