Rapid seroprotection against hepatitis B following the first dose of a Pre-S1/Pre-S2/S vaccine

Background/Aims: Will immunization with an experimental Pre-S1/Pre-S2/S hepatitis B vaccine (Bio-Hep-B™) induce faster seroprotection using fewer doses as compared with a yeast derived S vaccine (Engerix B®). Methods: Healthy volunteers, n=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-B™ 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 first dose, seroprotection was 70 and 25% in Pre-S/S and S vaccinees respectively. Area under the curve in vaccinees of Bio-Hep-B™; versus Engerix-B® showed mean anti-HBs level of 365±166 and 85±48 mIU/ml×day respectively (P=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-B™ and Engerix-B® respectively (P<0.025). Conclusions: Bio-Hep-B™ induces rapid seroprotection against hepatitis B in 60–70% of vaccinees, within 4–24 weeks after the first dose. Two instead of the conventional three doses of the Pre-S/S vaccine may be sufficient to induce adequate seroprotection.