IMMUNOGENICITY OF 2 RECOMBINANT HEPATITIS-B VACCINES IN OLDER INDIVIDUALS

PURPOSE: Currently available hepatitis B vaccines are recombinant, yea st-derived preparations given in 10-mug or 20-mug doses. The optimum d ose remains controversial. We sought to assess the relative immunogeni city of two hepatitis B vaccines, given in different doses, in older i ndividuals. PATIENTS AND METHODS: In a multicenter, double-blind, rand omized clinical trial, a total of 460 healthy subjects between 39 and 70 years of age were screened and immunized with either Engerix-B 20 m ug or Recombivax HB 10 mug in standard, intramuscular, 3-dose regimens . Of these, 397 subjects were eligible to continue vaccination. Immuno genicity was measured by determination of antibody to hepatitis B surf ace antigen (anti-HBs). Seroconversion and seroprotection rates, and g eometric mean titers of anti-HBs were calculated at 1, 3, 6, and 8 mon ths after the initial dose of vaccine. RESULTS: Seroprotection rates f or subjects receiving the 20-mug dose of vaccine were slightly, but no t significantly, greater than for subjects receiving the 10-mug dose, at each time point. However, at 3 months, males receiving the higher d ose had significantly higher seroprotection rates than males receiving the lower dose: 63% versus 37% (p <0.001). At 8 months, geometric mea n titers for the group receiving Engerix-B 20 mug were significantly g reater than that for the group receiving Recombivax HB 10 mug: 840 mIU /mL versus 340 mIU/mL (p = 0.001). CONCLUSIONS: Immunization with the 20-mug dose of recombinant hepatitis B virus vaccine appeared to resul t in more rapid development of seroprotective anti-HBs titers in older men and in higher titers of anti-HBs at the completion of vaccination when compared to the 10-mug dose. The latter data suggest that the 20 -mug dose may result in a longer duration of seroprotective anti-HBs t iters.