ABSTRACT
<p><b>OBJECTIVE</b>To study the immunogenicity and safety of recombinant yeast-derived hepatitis B vaccine (YDV) in adults.</p><p><b>METHODS</b>One hundred and twenty-four healthy teachers aged 22 approximately 58 years with serum negative HBsAg, anti-HBs, anti-HBc and with normal temperature were randomly selected from Beipiao city, Liaoning province. All the subjects were immunized with 5 microg/0.5 ml of YDV made by Beijing Institute of Biologic Products, for three doses at an interval of one and six months, respectively.</p><p><b>RESULTS</b>The positivity of serum anti-HBs was 35.0%, 83.3%, 65.5% and 32.7% with a geometric mean titre (GMT) of 12.6 mIU/ml, 402.0 mIU/ml, 70.3 mIU/ml and 20.3 mIU/ml, respectively, three, seven, 12 and 24 months after immunization. The positivity and GMT of serum anti-HBs appeared the highest seven months after immunization, then began to decrease sharply. The positivity and GMT of serum anti-HBs in women was higher than that in men either three, or seven, or 12, or 24 months after immunization. The positivity of serum anti-HBs in those of 35 years or over was lower than that less than 35 years, seven months after immunization, but no age difference could be found 12 months after immunization. No local or systematic adverse reactions were found in all the subjects within three days after immunization.</p><p><b>CONCLUSION</b>The recombinant yeast-derived hepatitis B vaccine (YDV) is immunogenic and safe for adults, but the persistency of serum anti-HBs in after immunization should be followed-up further.</p>