A 9-year follow-up study of the immunogenicity and long-term efficacy of plasma-derived hepatitis B vaccine in high-risk Chinese neonates.

The long-term immunogenicity of and protection provided by a plasma-derived hepatitis B vaccine was determined in a cohort of 98 susceptible Chinese neonates immunized in 1982-1983. Within 24 hours of birth, 89 infants received the first of three 30-micrograms doses of vaccine (at 0, 1, and 6 months) and were subsequently followed up by testing for serological markers of hepatitis B virus and by determining levels of alanine aminotransferase annually for 9 years. After the primary series of vaccine doses, 74 (83%) of 89 subjects developed antibody to hepatitis B surface antigen (anti-HBs). At the 9-year follow-up, 51% of vaccinees still had levels of antibody of > or = 10 mIU/mL, considered the protective level. Seven responders to vaccine (9.4% of 74 evaluable patients) developed antibody to hepatitis B core antigen, and in six of these responders, levels of anti-HBs increased transiently. None of the vaccinees developed chronic carriage of hepatitis B surface antigen or clinical hepatitis. Immunization of high-risk neonates with a plasma-derived hepatitis B vaccine can induce long-lasting protective immunity that can prevent or modify primary infection for at least 9 years. Booster doses are not necessary during this period.