ABSTRACT
Our objective was to investigate the effect of various reimmunization schemes for hepatitis B in adults with low or undetectable anti-HBs titers. Over 2 years, 10 μg of Saccharomyces cerevisiae-recombinant hepatitis B virus (HBV) vaccine (synthesized in China) was used in at least one standardized scheme to immunize 2,310 healthy male and nonpregnant female adults. Of these, 240 subjects tested negative for hepatitis B markers. These 240 subjects were equally divided into 4 groups. The first group, designated Engerix-40, was revaccinated with 40 μg Engerix-B; the second, Engerix-20, was revaccinated with 20 μg Engerix-B; the third, Chinese-20, was revaccinated with 20 μg Chinese-made yeast-recombinant vaccine; and the last group, Chinese-10, was revaccinated with 10 μg Chinese-made yeast-recombinant vaccine. Blood samples were collected before and 1, 2, 8, and 12 months after the first injection. The anti-HBs-positive conversion rates of the Engerix-40, Engerix-20, and Chinese-20 groups were higher than that of the Chinese-10 group (P < 0.01). Over time, the anti-HBs conversion rate increased in all groups, but values were significantly different from those for the other groups only in the Chinese-10 group (P < 0.001). The anti-HBs geometric mean titers (GMTs) of the Engerix-40, Engerix-20, and Chinese-20 groups were higher than in the Chinese-10 group (P < 0.05). Increased doses raise and maintain anti-HBs titers in subjects with low or undetectable titers after HBV vaccination.
The long-term immunogenicity of recombinant hepatitis B virus (HBV) vaccine: contribution of universal HBV vaccination in Italy
