[Comparison of antibody persistence after primary immunization with 5 μg and 10 μg recombinant hepatitis B vaccine among newborns with normal and high response: a five-year following-up]

Objective: To compare the antibody persistence 5 years after primary immunization with 5 μg and 10 μg recombinant hepatitis B vaccine (HepB) among newborns with normal and high response. Methods: Newborns who completed three doses of 5 μg HepB made by recombinant dexyribonucleic acid technique in Saccharomyces (HepB-SC) or 10 μg HepB made by recombinant dexyribonucleic acid technique in Hansenula polymorpha (HepB-HP) were recruited. Standardized questionnaire was used and blood samples were collected 1-6 months (T(0)) and five years (T(1)) after the third dose respectively. The titer of anti-HBs was detected by chemiluminescence microparticle imunoassay (CMIA). Those who achieved normal or high antibody response (anti-HBs titer ≥100 mIU/ml) were included in the study and the positive rate (≥10 mIU/ml) and titer of anti-HBs at T(1) were compared between 5 μg HepB group and 10 μg HepB group. Multivariable analysis was conducted to identify the independent factors associated with the antibody persistence. Results: The positive rate of anti-HBs at T(1) was 49.92% (943/1 883) and 75.92% (1 135/1 495) respectively in 5 μg HepB group and 10μg HepB group, the difference was significant (χ(2)=237.75, P<0.001). The anti-HBs geometric mean concentrations at T(1) were 10.23 mIU/ml (95%CI: 9.38-11.16) and 28.91 mIU/ml (95%CI: 26.65-31.35) in the two groups respectively, the difference was also significant (F=280.36, P<0.001). Among those whose anti-HBs titer was<10 mIU/ml at T(1), the distributions of anti-HBs titer were significantly different between 5 μg HepB group and 10 μg HepB group (χ(2)=39.75, P<0.001). The multivariable analysis showed that dosage of HepB was independently associated with both positive rate and titer of anti-HBs at T(1) after excluding the other factors[P<0.001, OR=1.44 (95%CI: 1.20-1.73); P<0.001, β=0.27 (95%CI: 0.14-0.40)]. Conclusion: Five year anti-HBs persistence after primary immunization with 10 μg HepB might be better than that after primary immunization with 5 μg HepB among infants who achieved normal or high anti-HBs response after primary HepB immunization.