[Anti-HBs persistence after primary vaccination with three doses of 5 μg recombinant hepatitis B vaccine among normal and high-responder infants: 10-year of follow-up].

Objective: Assess the 10-year Immune persistence and the predictors after primary vaccination hepatitis B vaccine (HepB) among normal and high-responder infants. Methods: A total of 1 838 Infants of 7-12 months old located in Jinan, Weifang, Yantai and Weihai of Shandong Province who were induced normal or high antibody response (anti-HBs titer ≥ 100 mIU/ml) after primary vaccination (three dose with 0-1-6 procedure) with 5 μg recombinant HepB among newborns were included in the study, in 2009. 3 ml of venous blood samples were collected at baseline survey (T ₀ ) and antibodies against hepatitis B surface antigen (anti-HBs), antibody against hepatitis B core antigen (anti-HBc) and hepatitis B surface antigen (HBsAg) were detected using chemiluminescence microparticle immunoassay (CMIA) method. A self-designed questionnaire was used to collect information including the infant's age, sex, birth weight, premature birth, birth number, delivery location and mother's HBV infection status. In 2014 (followed up for 5 years) and in 2019 (followed up for 10 years) (T ₁ ), 2 ml of venous blood samples were collected. Anti HBS and anti HBC were detected by CMIA method. Those with anti HBS<10 mIU/ml were detected by CMIA method. Multivariate unconditional logistic and linear regression models were used to analyze the influencing factors of anti-HBs positive rate and geometric mean concentration (GMC) at T ₁ . Results: After 10 years follow-up, 73.94% of the subjects (1 359/1 835) finished the follow-up. 51.15% of the subjects, a total of 625 were boys. The positive rate of anti-HBs was 100% at T ₀ and decreased to 53.44% (95% CI : 50.59%-56.26%) at T ₁ . The average annual decline rate of anti-HBs positive rate from T ₀ to T ₁ was 6.07%. The GMC of anti-HBs decreased from 607.89 (95% CI : 579.01-642.62) mIU/ml to 16.44 (95% CI : 15.06-18.00) mIU/ml. The average annual decline rate of anti-HBs GMC in 10-year follow-up was 30.30%. Multivariate logistic analysis showed that the positive rate of anti-HBs at T ₁ was lower in those who did not vaccinate the first dose in time ( OR =0.25, 95% CI :0.07-0.71). Compared with those with GMC<1 000 mIU/ml at T ₀ , those with GMC ≥ 1 000 mIU/ml had a higher positive rate of anti-HBs at T ₁ ( OR =2.29, 95% CI :1.76-2.97). Multivariate regression analysis showed that the GMC of anti-HBs at T ₁ was lower in those who did not vaccinate the first dose in time (β=-0.50, 95% CI :-1.24-0.24). Compared with those with GMC<1 000 mIU/ml at T ₀ , those with GMC ≥ 1 000 mIU/ml had a higher GMC of anti-HBs at T ₁ (β=0.81, 95% CI : 0.62-1.05). Conclusion: Anti-HBs GMC decreased in 10 years after primary vaccination of 5 μg recombinant hepatitis B vaccine among normal and high-responders. The anti-HBs persistence was mainly associated with whether the first dose was vaccinated in time and the level of anti-HBs at the end of primary vaccination.