Evaluation of the virtues and pitfalls in an HIV screening algorithm based on two fourth generation assays - A step towards an improved national algorithm.

Background: Fourth-generation immunoassays used for HIV screening, simultaneously detect anti-HIV antibodies and HIV-1 P24 antigen, but are prone to false-positive results. Usually, they are followed by highly specific third-generation assay, able to differentiate between HIV-1/2 infections. In Israel, screening algorithm is based on consecutive testing by two fourth-generation assays and confirmation by a third-generation test.