Types of HIV Tests
The body makes antibodies to try to fight HIV, although the antibodies cannot eradicate the virus. Antibody testing is often done in two parts. First a sensitive screening test is performed on the blood. If the screening test is positive, a second test is done to confirm that HIV antibodies are present. The types of tests have varied over the years. At first, the screening test used an enzyme-linked immunoassay (ELISA) with confirmatory testing by Western blot. This strategy did not test for HIV-2, sometimes misclassified HIV-2 infection, missed very early infections where antibody had not yet been produced, and sometimes produced indeterminate results.