In this randomized, observer-blind study, healthy adults received two doses of HBV-ISS at 0 and 4 weeks or three doses of HBV-Eng at 0, 4, and 24 weeks. The primary immunogenicity endpoint was the seroprotection rate (antibody 鈮?#xA0;10 mIU/mL) 8 weeks after the second dose of HBV-ISS compared to 4 weeks after the third dose of HBV-Eng.
A total of 2415 participants were randomized in a ratio of 3:1 to HBV-ISS (n = 1809) and HBV-Eng (n = 606). The percentage of subjects exhibiting a seroprotective immune response at the primary time point was significantly higher (95.1%) for HBV-ISS than for HBV-Eng (81.1%). Superiority of the seroprotective rates for HBV-ISS was demonstrated at all time points measured. Geometric mean concentrations were also significantly higher in the HBV-ISS group at all time points measured except at week 28 (24 weeks post-second dose of HBV-ISS and 4 weeks post-third dose HBV-ISS) at which time the antibody concentrations were similar. Both vaccines were welltolerated although injection-site reactions were reported at a higher rate in HBV-ISS recipients.
A short, two-dose regimen of HBV-ISS induced a superior antibody response than a three-dose regimen of a licensed hepatitis B vaccine and was well tolerated.