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Objective: To determine the duration of the immune response to plasma-derived hepatitis B vaccine among healthcare workers responding to booster doses of intradermal (ID) or intramuscular (IM) vaccine in 1986 and those with protective levels of antibody to hepatitis B surface antigen (anti-HBs) in 1986 without booster vaccine. Both groups received a primary hepatitis B vaccine series 24 to 36 months earlier., Design: Cross-sectional follow-up study two years later of an inception cohort defined in 1986., Setting: An academically affiliated metropolitan county hospital., Participants: Group 1: Hospital employees responding to booster doses of hepatitis B vaccine given ID or IM in 1986 due to low anti-HBs levels. Forty-one (82%) of 50 eligible persons were evaluated. Group 2: Persons not receiving booster vaccine in 1986 due to protective levels of anti-HBs. A random sample of 95 persons was drawn from a pool of 152 participants with protective levels in 1986. Sixty-five (68%) of 95 contacted persons were restudied., Results: In 1988, 14 (64%) of 22 previous ID responders had anti-HBs levels greater than or equal to 10 milli-international units (mIU)/mL, compared with 17 (89%) of 19 IM responders (p = .055). The 1988 geometric mean titer of IM recipients was 66.4 +/- 4.5 mIU/mL and of ID recipients was 20.7 +/- 7.4 (p = .04). None of 65 Group 2 subjects' anti-HBs titers dropped below 10 mIU/mL by 1988., Conclusions: Plasma-derived hepatitis B vaccine recipients with anti-HBs levels greater than or equal to 10 mIU/mL at 24 to 36 months after primary immunization are likely to maintain these levels two years later. The diminished durability of the antibody response together with the increased rate of local side effects associated with the ID injection route may limit its applicability as an alternative to using IM booster doses of hepatitis B vaccine.

Although the efficacy of hepatitis vaccine is well documented, the duration of immunity of healthy adults after vaccination is unknown. We studied 245 hospital employees 3 years after primary vaccination with hepatitis B vaccine to determine the prevalence of immunity indicated by levels of antibody to hepatitis B surface antigen of 10 mIU/mL or greater; and to compare the immunogenicity of low-dose intradermal vaccine with standard-dose intramuscular vaccine in persons found to be seronegative. Thirty-eight percent of employees studied had antibody levels less than 10 mIU/mL. Low levels were associated with smoking, older age, and higher body-mass index. Seventy-eight percent of persons with low antibody levels responded to a single booster vaccine. Two micrograms of intradermal vaccine was as effective as 20 micrograms of intramuscular vaccine in inducing an antibody response; however, intradermal vaccine was associated with more local reactions (42% compared with 17%). Many healthy adults will need periodic boosters of hepatitis B vaccine to maintain production of antibody to hepatitis B surface antigen; low-dose intradermal booster schedules may be feasible.