effect of vaccination against hepatitis b in cases with isolated anti-hbc

background: 1.3% of people in iran are positive for anti-hbc antibody.the objective of this study is to determine the rate of seroconversion in those with persistent isolated anti-hbc after vaccination. materials and methods: in a quasi-experimental study, 94 persons with isolated anti-hbc antibody who were referred to tehran blood transfusion organization between 2002 and 2004 were selected through a convenient sampling. they were given recombinant hepatitis b vaccine on 0, 1 and 6 months. immunization was defined by anti-hbs antibody titer |≥|10 miu/ml, 1-2 months after administration of the last dose. results: response to hb vaccination consisted of 28%, 62% and 76% after each injection, respectively. the total response rate was 80% (n=75). nineteen (20%) persons were negative for anti-hbs even after three doses of hb vaccination. factors associated with decreased response to vaccination were positive anti-hbe (or=6.4, p=0.008), history of bloodletting (or=3.1, p=0.039) and prior history of being hbsag positive (or=5.6, p=0.002). conclusion: although there were some differences between the response rates after each vaccine injections observed in our study and similar ones, the total response was nearly the same.