Sensitivities of the anti-HBc assay using oral fluid vary between groups and subgroups; from 21.6% in the Midwest region of Brazil (subgroup from GII) to 70.6% in the ambulatory group (GI), probably due to the high number of active infections in group I. Previous studies also demonstrated low sensitivity of anti-HBc detection in oral fluid samples; 13 and 43% reported by Amado et al. [32] and Nokes et al. [30] respectively. This evidence concerns the gene KRT88P and infection.