OBJECTIVETo assess the 24-month efficacy after booster vaccination with 3 doses of hepatitis B vaccine among low-response adults in Zhangqiu county of Shandong province.

METHODSA total of 24 237 adults aged 18-49 years old, never received HepB vaccination, without HBV infection history, and had been living at 3 towns of Zhangqiu county in Shandong province for more than half a year in september, 2009, were collected blood samples of 3-5 ml. A total of 11 590 adults who were negative for hepatitis B virus (HBV) surface antigen (HBsAg) , antibody to HBsAg (Anti-HBs) and antibody to HBV core antigen (Anti-HBc), were divided into four groups randomly and were vaccinated following the schedule of 0-1-6 with 20 µg hepatitis B vaccine made by recombinant deoxyribonucleic acid techniques in Saccharomyces cerevisiae (HepB-SC), 20 µg hepatitis B vaccine made by Chinese hamster ovary cell (HepB-CHO), 10 µg HepB-SC and 10 µg hepatitis B vaccine made by recombinant deoxyribonucleic acid techniques in Hansenula Polymorpha (HepB-HP), respectively. The adults who were low-response to the primary hepatitis B vaccination (10 mU/ml ≤ anti-HBs<100 mU/ml) were divided into four groups by cluster random sampling. These groups were revaccinated with 3-dose of above-mentioned four kinds of HepB respectively. Blood samples were drawn from 1 month (T1) and 24 month (T24) after the 3 dose revaccination, respectively. Anti-HBs and anti-HBc was detected by Chemiluminescence Microparticle Imunoassay (CMIA).

RESULTSOut of the 8 592 adults who have accepted the primary vaccination of hepatitis B and been collected the blood samples, 1 306 subjects showed low-response. A total of 718 low-response subjects were collected blood samples after T1 and T24 following 3 doses of booster vaccination. The proportion of the four groups was 32.3% (232/718), 25.8% (185/718) , 19.3% (139/718) , 22.6% (162/718) , respectively. The average proportion of anti-HBs ≥ 100 mIU/ml were decreased from 77.58% after T1 to 35.63% after T24 (χ² = 256.87, P < 0.01). The proportion of anti-HBs ≥ 100 mIU/ml in T24 were 38.8% (90/177), 39.5% (73/185), 25.2% (35/139) and 35.8% (58/162) in four groups, respectively. The proportion of anti-HBs>100 mIU/ml in T24 was significantly different among groups (χ² = 8.81, P = 0.032). The average geometric mean concentration (GMC) was significantly reduced from 443.53 mIU/ml after T1 to 48.98 mIU/ml after T24 (F = 439.41, P < 0.01). The GMC was 60.26 (45.71-77.62), 1.29 (38.90-69.18) , 35.48 (25.70-48.98) and 46.77 (33.88-6.07) mIU/ml in four groups, respectively (F = 1.97, P = 0.117) . Compared with vaccinated 20 µg HepB-SC, the proportion of anti-HBs ≥ 100 mIU/ml and GMC was 0.56 (0.35-0.91) and -0.20 (-0.39--0.02) times. The positive of HBsAg was not found and the positive rate of anti-HBc was 2.6% (18/692) in T24.

CONCLUSIONProtective antibody following booster vaccination with three doses of hepatitis B vaccines among low-response adults after 2 years fade faster. Antibody level of anti-HBs in T24 was corrected with the booster vaccine type and age. 20 µgHepB-SC seemed better than 10 µg HepB-SC.