Immunogenicity of two recombinant hepatitis B vaccines in older individuals

PURPOSE: Currently available hepatitis B vaccines are recombinant, yeast-derived preparations given in 10- [mu] g or 20-[mu] g doses. The optimum dose remains controversial. We sought to assess the relative immunogenicity of two hepatitis B vaccines, given in different doses, in older individuals. PATIENTS AND METHODS: In a multicenter, double-blind, randomized clinical trial, a total of 460 healthy subjects between 39 and 70 years of age were screened and immunized with either Engerix-B 20 [mu] g or Recombivax HB 10 [mu] g in standard, intramuscular, 3-dose regimens. Of these, 397 subjects were eligible to continue vaccination. Immunogenicity was measured by determination of antibody to hepatitis B surface antigen anti-HBs). Seroconversion and seroprotection rates, and geometric mean titers of anti-HBs were calculated at 1, 3, 6, and 8 months after the initial dose of vaccine. RESULTS: Seroprotection rates for subjects receiving the 20-[mu] g dose of vaccine were slightly, but not significantly, greater than for subjects receiving the 10-[mu] g dose, at each time point. However, at 3 months, males receiving the higher dose had significantly higher seroprotection rates than males receiving the lower dose: 63% versus 37% (p