ABSTRACT
It is important to differentiate whether isolated anti-HBc is due to false positive results or the prior exposure to hepatitis B virus, because individuals with false-positive anti-HBc can benefit from vaccination and their blood can be safely transfused. To distinguish between these two conditions, we evaluated the serologic response to hepatitis B vaccine. Ninety subjects with isolated anti-HBc [cases] and 100 subjects with totally negative hepatitis B serologic markers [controls]] were recruited to receive three doses of hepatitis-B [HB] vaccine. Thirty days after the first dose of the vaccine, anti-HBs titers were checked and individuals with anti-HBs titer >50 mlU/mL did not receive additional doses of the vaccine. However, others completed the vaccination course, and another blood sample was collected 30 days after the third dose to measure anti-HBs level. Nineteen [21.1%] cases and three [3%] controls had no sero-conversion [anti-HBs titers <10 mlU/mL] 30 days after the third dose [p<0.000l]. Primary response, defined as the development of anti-HBs antibody titers >10 mlU/mL 30 days after the third dose, was observed in 43 [47.8%] cases and 92 [92%] controls [p<0.000l]. Also, 31.1% of cases developed anti-HBs titers > 50 mlU/mL 30 days after the first dose of vaccine, but the rate was significantly lower [5%] in the control group [P<0.0001]. Furthermore, half of the individuals with positive isolated anti-HBc developed protective levels of anti-HBs after three doses of HB vaccination. More than 75% of individuals with positive isolated anti-HBc can benefit from vaccination and can be included in donor pool. Also, one fifth seemed to have occult HBV infection. So HB vaccination may be used as a diagnostic tool for clarifying the situation of the subjects with isolated anti-HBc