Responses to hepatitis B vaccine in isolated anti-HBc positive adults.

Immune responses of isolated anti-HBc subjects are not well characterized in populations in China. This study aimed to evaluate immune responses to hepatitis B vaccination in isolated anti-HBc positive subjects. A cohort of 608 subjects were selected and separated into isolated anti-HBc (negative for HBsAg and anti-HBs, positive for anti-HBc) and control (negative for HBsAg, anti-HBs, and anti-HBc) groups, who were matched by age and sex. All subjects received 3 doses of hepatitis B vaccine (20mg) at months 0, 1, and 3, followed by testing for serological responses 1 month after the third vaccination. The positive seroprotection rate and geometric mean titer (GMT) for hepatitis B surface antibody (anti-HBs) of isolated anti-HBc subjects were significantly lower than those in the control group(86.2% vs. 92.1%, P = 0.02; 47.26 vs. 97.81 mIU/mL, P < 0.001). When stratified by age, positive seroprotection rate in the isolated anti-HBc group were 92%, 88.5% and 79.4% in the 20-34, 35-49, and 50-60 y old subgroups, respectively (chi(2) = 5.919, P = 0.04). Additionally, the GMT level for anti-HBs in the isolated anti-HBc group for different age subgroups were 104.43, 47.87 and 31.79 mIU/mL respectively (chi(2) = 19.44, P < 0.001). The GMT level for anti-HBc before vaccination were negatively correlated with GMT for anti-HBs after 3 doses of hepatitis B vaccine (r = -0.165, P < 0.001). In conclusion, isolated anti-HBc positive subjects can achieve good immune responses after hepatitis B vaccination, and the positive seroprotection rate and GMT level for anti-HBs were lower than the control group. Better responses could be observed in young adults, and significant negative correlations were found between GMT of anti-HBc before vaccination and GMT of anti-HBs after vaccination.