The current European guidelines for the treatment of chronic hepatitis B and C in HIV infected patients [23] do not recommend vaccinating of IAHBc–positive individuals and consequently do not provide information on the efficacy and the significance of vaccination in anti-HBc, OBI-positive patients, although some authors [24–26] have suggested determining HBV DNA levels in order to rule out OBI in individuals who fail to respond to HBV vaccination before giving a primary HBV immunisation series. This evidence concerns the gene KRT88P and chronic hepatitis B virus infection.