All donations were screened by US-required serologic HBV tests and for HBV DNA by MP-NAT (Novartis/Gen-Probe). Further testing by individual-donation polymerase chain reaction (ID-PCR) confirmed various classes of MP-NAT-reactive or -nonreactive donations. The hepatitis B surface antigen (HBsAg)-yield method was used to calculate incidence and the incidence-window-period model used to define residual risk.