Safety and immunogenicity of a modified process hepatitis B vaccine in healthy infants.

Background: A modified process hepatitis B vaccine (mpHBV) uses higher phosphate content in the manufacturing process relative to the current product, Recombivax-HB. The higher phosphate is thought to improve antigen presentation, and thereby, increase antibody production. The mpHBV was previously shown to be well tolerated and immunogenic in adults. The current study tested a 2-, 4-, 6-month vaccination schedule and a higher dose formulation (10 μg mpHBV) in healthy infants.

Methods: In a randomized, double-blind study, healthy infants (N = 1718), approximately 2 months of age, received a 0.5-mL intramuscular dose of 5-μg mpHBV, Recombivax-HB (5 μg), 10-μg mpHBV, or Engerix-B (10 μg) at day 1, month 2, and month 4 (2, 4, 6 months of age). Serum antibody to hepatitis B surface antigen (anti-HBs) was analyzed at month 7. The geometric mean titer (GMT) and seroprotection rate (SPR; % subjects with anti-HBs titer ≥ 10 mIU/mL) were determined 1 month after the third dose.

Results: Month 7 SPRs were 99.3% (402/405, 95% confidence interval [CI]: 98.3, 100) in the 5 μg mpHBV group, 100.0% (398/398, 95% CI: 99.9, 100) in the 10 μg mpHBV group, 98.5% (400/406, 95% CI: 97.2, 99.8) in the Recombivax-HB group, and 99.5% (398/400, 95% CI: 98.7, 100) in the Engerix-B group. Month 7 GMTs (mIU/mL) were 748.2 (95% CI: 672.0, 833.1) in the 5 μg mpHBV group, 981.5 (95% CI: 891.0, 1081.2) in the 10 μg mpHBV group, 376.8 (95% CI: 331.4, 428.5) in the Recombivax-HB group, and 556.6 (95% CI: 491.8, 629.9) in the Engerix-B group. The percentages of subjects reporting injection-site or systemic adverse events were similar across the vaccination groups.

Conclusions: All 4 hepatitis B vaccines elicited high anti-HBs SPRs. After dose 3, anti-HBs GMT were highest in the 10 μg mpHBV group, but did not meet the predefined criteria for superiority. All vaccines were well tolerated.