CLINICAL AND IMMUNOLOGICAL INVESTIGATION OF A NEW COMBINED HEPATITIS-A AND HEPATITIS-B VACCINE

As with hepatitis B vaccines, the recently developed hepatitis A vacci ne is suitable not only for individual protection, but also for public health control measures. For introduction into routine immunisation p rogrammes, however, hepatitis A vaccine should preferably be combined with other already established vaccines. In particular, a combination of hepatitis A and hepatitis B vaccines would be appropriate. We inves tigated a new combined hepatitis A/hepatitis B vaccine comparing its t olerability and immunogenicity with that obtained after separate or mi xed simultaneous administration of the two components. Three groups of healthy volunteers, each of approximately 50 persons, were included. All were negative for hepatitis A and hepatitis B markers and had norm al liver enzyme values. They received hepatitis A (720 ELISA units) an d hepatitis B (20 mu g) vaccines in the deltoid muscle, combined, mixe d or separately, according to a 0, 1, 6-month schedule. Blood samples for determination of antibodies to hepatitis A virus (anti-HAV) and he patitis B virus (anti-HBs) and of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were drawn at months 0, 1 , 2, 6, and 7. Local and systemic reactions were monitored by means of questionnaires. The results of our study demonstrate that the combine d hepatitis A and B vaccine is well tolerated and highly immunogenic. The seropositivity and seroprotection rates were 100% for both antigen s in all groups. Surprisingly, anti-HAV and anti-HBs antibody titres a fter the combined and mixed vaccines were significantly higher compare d with the respective monovalent vaccines injected separately. (C) 199 4 Wiley-Liss, Inc.