OBJECTIVETo access the antibody persistence 24-month after revaccination with 3-dose of hepatitis B vaccine (HepB) among non-response adults.

METHODSA total of 24 237 healthy adults who had no histories of hepatitis B infection and hepatitis B vaccination, resided in the local area for more than six months and were aged 18-49 years were selected from 79 villages of Zhangqiu county, Shandong province, China in 2009. Blood samples were obtained and hepatitis B surface antigen (HBsAg), antibody against hepatitis B surface antigen (anti-HBs) and antibody against hepatitis B core antigen (anti-HBc) were detected using ELISA method. A total of 11 590 persons who were negative for all of these indicators were divided into four groups by cluster sampling methods. Each group was vaccinated with one of the following four types of HepB at 0-, 1-, 6-months schedule: 20 µg HepB derived in Saccharomyces Cerevisiae (HepB-SC), 20 µg HepB derived in Chinese hamster ovary cell (HepB-CHO), 10 µg HepB-SC and 10 µg HepB derived in Hansenula Polymorpha (HepB-HP). Blood samples were collected one month after the third dose of primary immunization and tested for anti-HBs using chemiluminescence microparticle immunoassay (CMIA). The non-responders were revaccinated with three doses of HepB at 0-, 1-, 6-months schedule and the type of HepB was the same as which was used for primary immunization. Blood samples were collected one month (T1) and two years (T24) after revaccination and anti-HBs, antibody against hepatitis B core antigen (anti-HBc) and hepatitis B surface angtigen (HBsAg) (if anti-HBs < 10 mU/ml) were detected by CMIA. χ(2) test was used to compared age, gender and body mass index (BMI) between different groups and the anti-HBs positive rate at T1 and T24; analysis of variance (ANOVA) was used to compare the geometric mean concentration (GMC) of anti-HBs between difference groups. The risk factors associated with positive rate of anti-HBs and GMC of anti-HBs were identified by multiple logistic regression analysis and multifactor linear regression model analysis respectively.

RESULTSA total of 900 non-responders were identified and 71.7% (645/900) of them completed three-dose revaccination and blood collection after revaccination. 467 (72.4%) non-responsive adults were followed up at T24. The anti-HBs positive rate decreased from 85.65% (95% CI: 82.14%-88.71%) at T1 to 60.60% (95% CI: 56.01%-65.06%) at T24 and the corresponding GMC decreased from 175.62 (95% CI: 139.03-221.84) mU/ml to 21.43 (95% CI: 17.62-26.06) mU/ml. Multivariate analysis showed that positive rate of anti-HBs at T24 was associated with gender, HepB type for revaccination and anti-HBs level at T1, but only anti-HBs level at T1 was associated with the anti-HBs titer at T24. No subject showed HBsAg seroconversion and anti-HBc conversion rate was 3.64% (17/467) at T24.

CONCLUSIONAnti-HBs titer decreases rapidly two years after HepB revaccination among non-responsive adults, but more than half non-responderd still kept anti-HBs above protective level. The immunity durability after revaccination was associated with gender, HepB type for revaccination and anti-HBs titer one month after revaccination.