Pii: S0168-8278(00)00082-9

Background/Aims: Will immunization with an experimental Pre-S1/Pre-S2/S hepatitis B vaccine (Bio-Hep-Be) induce faster seroprotection using fewer doses as compared with a yeast derived S vaccine (Engerix B). Methods: Healthy volunteers, nˆ 36, mean age 23 y, randomized to receive 2 or 3 doses of both vaccines given months 0 and 6, or 0, 1 and 6. Results: Following primary immunization, seroprotection occurred in 6, 39, 53 and 60% in the Bio-Hep-Be group at weeks 1, 2, 3 and 4, compared with 0, 12, 18 and 12.5% in the Engerix-B vaccinees, respectively. Six months following injection of the ®rst dose, seroprotection was 70 and 25% in Pre-S/S and S vaccinees respectively. Area under the curve in vaccinees of Bio-Hep-Be; versus Engerix-B showed mean anti-HBs level of 365 ^ 166 and 85 ^ 48 mIU/ml £ day respectively (Pˆ 0.012). At month 7, 100% seroprotection was achieved in both groups while anti-HBs rose from 81 to 28 800 mIU/ml and from 12 to 923 mIU/ml in recipients of Bio-Hep-Be and Engerix-B respectively (P , 0.025). Conclusions: Bio-Hep-Be induces rapid seroprotection against hepatitis B in 60±70% of vaccinees, within 4±24 weeks after the ®rst dose. Two instead of the conventional three doses of the Pre-S/S vaccine may be suf®cient to induce adequate seroprotection. q 2001 European Association for the Study of the Liver. Published by Elsevier Science B.V. All rights reserved.