Abstract
BACKGROUND. The duration of protection provided by hepatitis B vaccination is unknown, but the presence of immune memory can be evaluated indirectly by measuring the immune response to a booster dose of vaccine.
METHODS. Participants included 74 adolescents (aged 11.7–14.9 years) who had received a plasma-derived 3-dose primary vaccine series and 138 adolescents (aged 10.0–14.7 years) and 166 children (aged 5.0–7.0 years) who received a recombinant 3-dose primary vaccine series. All were born to hepatitis B surface antigen–negative mothers and had received the first dose of hepatitis B vaccine within 7 days of birth. The proportion of participants with serologic evidence of protective immunity (antibody to hepatitis B surface antigen ≥10 mIU/mL) at baseline (prebooster), the proportion who developed an anamnestic response (increase to ≥10 mIU/mL or at or more than fourfold increase in antibody to hepatitis B surface antigen to >10 mIU/mL), and the geometric mean concentration by 1, 2, and 4 weeks after a 5-μg recombinant vaccine booster dose were determined.
RESULTS. No participant had evidence of chronic hepatitis B virus infection. Overall, 99% of the group of children who received recombinant hepatitis B vaccine, 83% of the group of adolescents who received recombinant hepatitis B vaccine, and 69% of the group of adolescents who received the plasma-derived vaccine had an anamnestic response to a booster dose; among responders, the geometric mean concentration at 2 weeks postbooster was 3360 and 128 mIU/mL among adolescents who received plasma-derived vaccine with antibodies to hepatitis B surface antigen ≥10 and <10 mIU/mL at baseline, respectively, compared with 1283 and 369 mIU/mL among adolescents who received recombinant hepatitis B vaccine and 5091 and 696 mIU/mL for children who received recombinant hepatitis B vaccine. The anamnestic response rate at 2 weeks postbooster among participants with antibodies to hepatitis B surface antigen <10 mIU/mL at baseline was inversely associated with age; 97% of 5-year-olds responded compared with 60% of 14-year-olds.
CONCLUSIONS. Although most participants responded to a booster dose of hepatitis B vaccine, the significance of the increased proportion of nonresponses among older adolescents might indicate waning immune memory.