[Antibody persistence following primary vaccination with hepatitis B vaccine among normal and high-responder adults: a 5-year follow-up study].

Objective: To evaluate the 5-year antibody persistence and the risk factors associated with the persistence after primary vaccination of hepatitis B vaccine (HepB) among normal or high-response adults.
Methods: A 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 in north 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). The normal and high-responder was followed up and their demographic characteristic (including age, gender), histories of hepatitis B infection, hepatitis B vaccination, smoking, drinking and chronic diseases were investigated. Blood samples were collected one month (T1) and five years (T2) and anti-HBs, anti-HBc and HBsAg (if anti-HBs<10 mU/ml) were detected by CMIA. A total of 1 902 participants were followed up and 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.
Results: Among 1 902 adults, 824 (43.32%) were male and 1 078 (56.68%) were female. The anti-HBs positive rate was 100% at T1 and it decreased to 73.29% (1 394 cases) at T2. The corresponding GMC was decreased from 1 527.15 (95%CI: 1 437.84-1 622.01) mU/ml at T1 to 35.07 (95%CI: 32.20-38.19) mU/ml at T2. When comparing with those vaccinated 20 μg HepB-SC, the significantly lower positive rate at T2 was observed in those vaccinated 10 μg HepB-SC group and 10 μg HepB-HP group. The OR (95% CI) was 0.41 (0.28-0.61) and 0.27 (0.18-0.39), respectively. The GMC of anti-HBs was also significantly lower among those vaccinated 10 μg HepB-SC and 10 μg HepB-HP. The b (95%CI) was -0.20 (-0.28- -0.12) and -0.36 (-0.44- -0.29) , respectively. When comparing with those occasionally drinking, the significantly lower positive rate at T2 was observed in those regular drinking. The OR(95%CI) was 0.51(0.30-0.87). The GMC of anti-HBs in age group of 18-29 was significantly higher than those in 40-49 age group; the b (95%CI) was -0.10(-0.18- -0.01). When comparing with those whose anti-HBs titer was less than 999 mU/ml at T1, the significantly higher positive rate of anti-HBs at T2 was observed in those whose anti-HBs titer was 1 000-1 999 mU/ml, those whose anti-HBs titer was 2 000-2 999 mU/ml and those whose anti-HBs titer was ≥10 000 mU/ml. The OR (95%CI) was 10.11 (6.90-14.82), 20.42 (13.98-29.82) and 54.58 (22.08-134.92), respectively. When comparing with those whose anti-HBs titer was ≤999 mU/ml at T1, the GMC of anti-HBs at T2 was also significantly higher among those whose anti-HBs titer at T1 was 1 000-1 999 mU/ml, those whose anti-HBs titer at T1 was 2 000-2 999 mU/ml and those whose anti-HBs titer at T1 was ≥10 000 mU/ml. The b (95%CI) was 0.55 (0.47-0.62), 0.94 (0.88-1.00) and 1.63 (1.54-1.72), respectively. Nobody was found positive to HBsAg at T2 and the conversion rate of anti-HBc was 3.89% (74/1 902) at T2.
Conclusion: Anti-HBs GMC decreased rapidly at T2 among normal and high-responder adults, while the positive rate of anti-HBs still kept at a high level. The antibody persistence among normal and high-responder adults at T2 was associated with HepB type, age, history of drinking and GMC of anti-HBs at T1.