Description: The HIV Antigen/Antibody Combo with Reflex to Confirmation test is a serum test that is a CDC-recommended algorithm for laboratory diagnosis of HIV infection, including acute and primary infection. Reactive (repeatedly) specimens must be investigated by additional supplemental tests. A negative test for an individual does not preclude exposure to or infection with HIV-1 and/or HIV-2. Negative results can occur if the quantity of the marker present in the sample is too low for detection by the assay or if the marker is not present during the stage of disease in which a sample is collected.