Hepatitis B (HepB) infection remains a global public health problem, particularly in China. Vaccination for children and adult who are unvaccinated is an effective method for preventing the disease. In this study, we aimed to compare the effects of increased dosage of HepB vaccine on immunogenicity in healthy children and adults. A phase III, controlled, double-blinded clinical trial was performed. The subjects were assigned into groups I (age 5-14 y), II (age 15-24 y), and III (age ≥ 25 y). Subjects were randomly administered either 10 or 5 μg recombinant HepB vaccine; blood samples were collected before and after vaccination to estimate immunogenicity. The results showed that the seroconversion rate and geometric mean concentration of antibody to hepB surface antigen (anti-HBs) did not differ significantly between the dosages in each age group. Anti-HBs levels were reduced with age, and this effect was more obvious in adults administered 5 μg HepB vaccine. In conclusion, both vaccine dosages could be used to immunize children, and the 10 μg vaccine could be used for adults ages 15-24 y, whereas a higher dosage of the HepB vaccine may be required for adults ages 25 y and older.
Keywords: adult; age; antigen dosage; children; hepatitis B; immunogenicity; vaccine.