Can monovalent hepatitis A and B vaccines be replaced by a combined hepatitis A/B vaccine during the primary immunization course?

A combined hepatitis A/B vaccine (Twinrix Adult(TM)) has been licensed in G ermany since 1997. We investigated possible differences in immunogenicity a nd safety when changing over from vaccinations with monovalent vaccines mad e by different manufacturers to vaccinations with the combined hepatitis A/ B vaccine in an open, randomized, multicenter trial. We therefore compared four different schemes changing over from concomitant vaccinations with mon ovalent vaccines against hepatitis A and B (Havrix 1440(TM) + Engerix-B(TM) or Vaqta(TM) + Gen H-B-Vax(TM)) to combined vaccination against hepatitis A + B with three injections of the combined hepatitis A/B vaccine (0, 1, an d 6 month schedule). Local and general symptoms were mostly mild in all fiv e groups. With complete three-dose course using the combined vaccine or an early changeover from monovalent vaccines to the combined vaccine, higher o verall anti-HBs seroprotection rates and geometric mean concentrations (GMC s) against hepatitis B could be achieved as early as after 2 months as comp ared to those groups switching later to the combined vaccine. This study de monstrated for the first time that switching from monovalent hepatitis A an d B vaccinations to the combined hepatitis A and B vaccination has no negat ive influence on the tolerability and improves the immunogenicity. (C) 2000 Elsevier Science Ltd. All rights reserved.