Efficacy of Hepatitis B vaccine in those who lost Hepatitis B surface antigen during follow-up: Efficacy of HBV vaccine in those who lost HBsAg

BACKGROUND: The level of HBsAg in some chronic hepatitis B virus (HBV)-infected individuals may decline over time so that it is not detectable in serum. OBJECTIVE: To assess the efficacy of HBV vaccine in those who lost their HBsAg without seroconverssion to anti-HBs antibody. PATIENTS AND METHODS: From April 1993 to December 2008, of 1603 chronic HBV-infected individuals, 34 (22 men and 12 women) became HBsAg-negative in follow-up visits, with no detectable anti-HBs antibody and HBV DNA in their sera. They received HBV vaccination at 0, 1 and 6 months (case group). Fifty-two subjects (30 men and 22 women) who were negative for HBsAg, anti-HBs and anti-HBc antibody, received HBV vaccination according to the said schedule (control group). Anti-HBs antibody was assessed one month after the last dose of vaccination in the both groups. RESULTS: The mean±SD age of the case and control groups was 38±12.7 and 33.4 ± 8.6 years, respectively (p = 0.07). The sex distribution between these two groups were similar (p = 0.652). The mean ± SD years of follow-up for the case group was 7.6 ± 4.5 years. Anti-HBs antibody level ≥ 10 IU/L was found in 8 (24%) subjects in the case group and in 45 (87%) in the control group (p < 0.001). The mean±SD anti-HBs antibody level in the case group was 68 ± 32.66 and in the control group 344.6 ± 38.9 IU/L (p < 0.001). CONCLUSIONS: We found that nearly 24% of chronic HBsAg-positive subjects who lost their HBsAg responded to HBV and the remaining cases need to be followed for occult HBV infection.