Immunogenicity of a combined hepatitis A and B vaccine in healthy young adults

Combining several vaccines in a single formulation can change the potency o f the vaccine antigens. Previous studies suggested a higher immunogenicity of a new combined hepatitis A and B vaccine compared with the monovalent he patitis B vaccine. We investigated the immune response to hepatitis B surfa ce antigen 1 month after the third vaccine dose in 282 healthy adults who h ad received either a monovalent hepatitis B vaccine (n = 148) or the combin ed hepatitis A/B vaccine (n = 134). A slight trend towards higher geometric mean titres of anti HBs was found at this point in time in the group immun ised with the combined vaccine, especially in the few vaccinees with preexi sting antibodies against hepatitis A virus. However none of these differenc es was statistically significant, arguing against an advantage of the combi ned vaccine regarding hepatitis B immunisation. (C) 2000 Elsevier Science L td. All rights reserved.