Effects of hepatitis B vaccine boosters on anti-HBs-negative children after primary immunization.

This study was aimed at evaluating the changes of hepatitis B surface antibody (anti-HBs) titer after booster vaccinations in 5-15-year-old children with negative antibodies (<10 mIU/mL). 225 subjects (mean age, 9.28 ± 2.95 years) included in the study consisted of 123 males and 102 females, with a complete hepatitis B vaccination during infancy. The participants were divided into 3 groups according to their pre-booster anti-HBs level: Group I, <0.1 mIU/mL; Group II, 0.1 to <1.0 mIU/mL; Group III, 1.0 to <10.0 mIU/mL. All the participants were administered 3 doses of booster hepatitis B vaccination (0-1-6 month, 20 µg), and changes in the levels of antibodies were examined at 4 time-points (one month after the first and the third dose, one year and 5 years after the third dose). The seroprotective rate (defined as anti-HBs ≥10.0 mIU/mL) among 225 subjects at the 4 time-points were 93.8%, 100%, 83.6% and 73.4%, respectively (χ2 = 90.29, p < 0.05). The seroprotective rate (≥10 mIU/mL) and anti-HBs geometric mean titer (GMT) in Group III were always higher than those in the other 2 groups (all p < 0.05). The immune effect of a 3 -dose booster revaccination is good, and the booster-induced immune response was correlated with the pre-booster titer level, and ≥1.0 mIU/mL ensuring a robust positive response, whereas titers below this value may indicate the need for a course of booster vaccination.

Comparison of the effect of two different doses of recombinant hepatitis B vaccine on immunogenicity in healthy adults.

The aim of this study was to evaluate the one-month immune response to 2 different doses (10 and 20 µg) of recombinant hepatitis B vaccine in adults aged 20-46 y. Subjects who were negative for hepatitis B surface antigen (HBsAg), hepatitis B antibody (anti-HBs), and hepatitis B core antibody (anti-HBc) were recruited. The participants were divided into 2 groups: group I received 3 doses of 10 µg hepatitis B vaccine at 0, 1 and 3 months, and group II received 3 doses of 20 µg at the same time points. The anti-HBs levels were measured one month after the third vaccination. Among 739 subjects, 62 (9.70%) were positive for HBsAg, and 317 subjects were eligible. The anti-HBs seroprotection rates (anti-HBs ≥ 10 mIU/mL was considered to indicate seroprotection) after the third vaccination were 88.05% and 94.06% in group I and group II respectively, and the geometric mean titers were 91.69 and 290.23 mIU/mL respectively. The difference in the seroprotection rate was not significant (χ(2) = 2.566, P > 0.05), but the GMT after the third dose was significantly lower for group I than for group II (F = 20.587, P < 0.05). Better responses were observed in young adults, especially in group I. In group I, the seroprotection rate and GMT were significantly higher in the 20-35 y group than in the 36-46 y group (P < 0.05); there was no significant difference compared to group II (P > 0.05). The hepatitis B vaccine has good immunological effect; the 20 µg dose can be used in adults aged 20-46 y and the 10 µg dose can be used in subjects aged 20-35 years, and it should be tested on a larger number of subjects before recommending it for adult routine vaccination.