PERSISTENCE OF ANTI-HBs ANTIBODIES IN HEALTHY IRANIAN CHILDREN VACCINATED WITH RECOMBINANT HEPATITIS B VACCINE AND RESPONSE TO A BOOSTER DOSE

Abstract- long-term protection against hepatitis b virus (hbv) is dependent on persistence of anti-hbs antibodies and/or strong immunological memory. in this study we evaluated the persistence of anti-hbs antibodies in healthy iranian children 5 years after primary vaccination and the response to a booster dose using recombinant hepatitis b vaccine. totally, 81 children who had received primary course of hepatitis b vaccine at 0, 1.5 and 9 months of age were included in this study. a booster dose of hepatitis b vaccine was administered at 5 years after completion of primary vaccination program. children were tested for anti-hbs antibody just before administration of booster dose and at 4 weeks after booster vaccination. an 81.5% seroprotection rate (anti-hbs > 10 iu/l) was observed 5 years after primary vaccination. after administration of booster dose, 100% of the children developed protective level of anti-hbs antibody and geometric mean titer rose from 206 iu/l to 1278 iu/l. these results indicate the existence of an effective immunological memory over a period of 5 years after primary vaccination with recombinant hepatitis b vaccine in healthy iranian children. acta medica iranica, 43(2): 79-84; 2005