HEPATITIS-B VACCINE BOOSTER DOSE - LOW-DOSE RECOMBINANT HEPATITIS-B VACCINES AS A BOOSTER DOSE

Background: The timing and best regimen for a booster dose of hepatiti s B vaccine have not been determined. Methods: Two studies were conduc ted to determine the response to a booster dose of 5 mu g recombinant hepatitis B vaccine. In the first study, a 5 mu g (0.5 ml) dose of Rec ombivax HB was administered intramuscularly 38 months after the initia l dose to 71 volunteers. In a second study, we offered a 5 mu g dose r ecombinant hepatitis B vaccine, either Recombivax HB (0.5 ml) or Enger ix B (0.25 ml), to students who had previously been immunized with thr ee doses of vaccine. Results: In the first study, among the 44 persons for whom postbooster sera were available, the geometric mean concentr ation of anti-hepatitis B surface antigens increased from 42 to 2090 m IU/ml after the 5 mu g (0.5 ml) dose of Recombivax. In the second stud y, after a 5 mu g (0.5 ml) dose of Recombivax, the geometric mean conc entration increased from 43 to 990 mIU/ml (n = 48), and in the group t hat received a 5 mu g (0.25 ml) dose of Engerix B, the concentration i ncreased from 83 to 2337 mIU/ml (n = 45) (p = 0.18 for postdose concen trations). Conclusion: A 5 mu g dose of recombinant vaccine results in an excellent booster response at a cost one fourth to one half that o f a full 1 ml dose of vaccine.