Evaluation of a reduced dose of hepatitis B vaccine administered intradermally

Abstract

Intradermal inoculation of hepatitis B vaccine (HBsAg subtype adw) caused no side effects, but the vaccine was less immunogenic than following intramuscular administration. Intradermal inoculation does not, therefore, offer a major advantage to the generally used intramuscular immunization. A single multisite intradermal administration of a reduced dose of vaccine did not result in a more rapid seroconversion compared to intramuscular inoculation. Although the antibody levels were similar after two intradermal or intramuscular injections given 1 month apart, the booster (third injection) at 6 months resulted in anti‐HBs levels that were about 10 times higher following intramuscular inoculation as compared to intradermal. All persons immunized developed anti‐HBs. The levels of anti‐HBs (a and w) were about 30–40% of the total anti‐HBs, and the proportion did not change significantly during the course of immunization. Cross‐protection against all HBV strains is thus also assured after intradermal administration of vaccine containing only one HBsAg subtype (adw). A skin reaction was elicited only in a small proportion of anti‐HBs‐positive individuals, and the reaction correlated roughly with the immune response.