The finding of isolated hepatitis B core antibody (isolated HBc) in absent of recent active hepatitis could cause by several scenarios, including false positive, remote infection without viremia, and occult infection with low viremia. Hepatitis B virus (HBV) vaccine booster could be a great prevention strategy for those who do not have HBV viremia. There is no standard consensus for management of this issue especially among HIV infected population. In addition, prior studies revealed that HIV-infected individuals had lower immunologic response to HBV vaccine than general population. This study intends to compare the immune response and safety of 4- versus 3-standard dose of hepatitis B virus vaccination in HIV-infected adults who has isolated HBc. The immunologic response will be evaluated after the participants receive vaccination.