Twelve-year follow-up of a prospective randomized trial of hepatitis B recombinant DNA yeast vaccine versus plasma-derived vaccine without booster doses in children

A total of 318 children were prospectively randomized in group 1 with two 5 -mu g doses of recombinant vaccine given at 0 and 1 month; in group 2 with three 5-mu g doses of recombinant vaccine given at 0, 1, and 6 months; or i n group 3 with three doses of plasma-derived vaccine given at 0, 1, and 6 m onths. Eleven subjects with a hepatitis B surface antigen antibody (anti-HB s) titer of less than 10 mIU/mL at 12 months were given an extra dose of va ccine and were excluded from analysis. No booster doses were given to any o ther subjects. All children were followed up yearly for the level of anti-H Bs titers and for the detection of hepatitis B infection. At the 12th year of follow-up, there were significantly fewer subjects with anti-HBs of 10 m IU/mL or above in group 1 (60.4%) when compared with group 2 (81.4%; P =.02 87) and group 3 (79.0%; P =.0381), The geometric mean titers (GMTs) of subj ects of group 1 were significantly lower than those of group 2 and group 3 throughout the 12 years of follow-up. A total of 65 subjects had one or mor e episodes of anamnestic response. No subject became positive for hepatitis B surface antigen (HBsAg); 2 became positive for hepatitis B core antigen antibody (anti-HBc). In conclusion, the long-term protective immunity was b etter with three doses of hepatitis B vaccine (either the recombinant or pl asma-derived) than with two doses. However, protection from hepatitis B inf ection could be equally achieved by either two doses or three doses of the vaccine. Booster doses were not necessary, probably because of effective an amnestic response.