Stevens Immunology-Serology Practice Test

After a positive HIV screening result, the test that best serves as confirmation is an assay that detects antibodies to both HIV-1 and HIV-2 and can distinguish between them. This aligns with the CDC’s current testing algorithm, which uses an HIV-1/HIV-2 antibody differentiation immunoassay to confirm infection and identify the specific virus type. If this differentiation test is reactive for either HIV-1 or HIV-2, a diagnosis is established. If the differentiation test is nonreactive or indeterminate after a reactive screen, a nucleic acid test measuring HIV RNA is used to resolve possible acute infection or discordant results. Western blot, once used for confirmation, is no longer recommended due to its limitations and potential for indeterminate results. HIV RNA testing has its place in certain scenarios, but it is not the standard confirmatory test immediately after a reactive antibody screening result unless the differentiation step is inconclusive.