Background: The duration of protection after hepatitis B vaccination of infants is unknown. We determined antibody to hepatitis B surface antigen (anti-HBs) and response to a booster dose 15 years after vaccination among Alaskan children born to hepatitis B surface antigen-negative mothers. These children had protective anti-HBs concentrations when tested after receiving a three-dose series of 2.5 microg recombinant hepatitis B vaccine starting at birth.
Methods: Participants received 5 microg of recombinant hepatitis B vaccine. Sera were collected at baseline, 10-14 days and 1 month after vaccination, and tested for antibody to hepatitis B core antigen (anti-HBc) and anti-HBs. An anamnestic response was defined as an anti-HBs increase within 15 days, from either undetectable to >/=10 mIU/mL, or, if the baseline concentration was detectable, a 4-fold increase.
Results: None of 37 participants (mean age 14.6 years) were anti-HBc positive. An anamnestic response (GMC=254 mIU/mL, range 16-2767 mIU/mL) was observed in 18 (51%) of 35 participants who had sera collected within 15 days after the booster.
Conclusions: In this small study, half of children who had received hepatitis B vaccine starting at birth did not have evidence of immune memory as measured by development of anamnestic responses to booster vaccination. Additional studies are needed to assess whether this indicates susceptibility to infection and whether persons vaccinated starting at birth may benefit from a hepatitis B vaccine booster to maintain long-term protection.