HIV-1 and HIV-2 are viruses that cause AIDS. HIV-1 is found worldwide, while HIV-2 is mainly found in western Africa but has spread to the US. HIV-1 and HIV-2 tests are used to screen and confirm HIV-1/HIV-2 infection, including acute infection, and to differentiate between HIV-1 and HIV-2 infection. There are different types of HIV tests, including:

• HIV-1/HIV-2 Rapid Screen: This test looks for HIV infection in your blood or saliva and can give results in about 20 minutes.

• HIV-1 Antibody Test: This test looks for HIV-1 antibodies in your blood. Your body makes these antibodies when you have been exposed to HIV-1.

• HIV Antibody/Antigen Tests: These tests look for HIV antibodies and antigens in your blood. An antigen is the part of the HIV virus that triggers your immune system to fight the infection. After an HIV exposure, antigens will show up in your blood sooner than antibodies. These tests can find an HIV infection as soon as 18 to 45 days after you were infected.

If a screening test is positive, a follow-up test is done to confirm the diagnosis. The follow-up test may include an HIV-1/HIV-2 antibody differentiation immunoassay, an HIV-1 NAT (nucleic acid test), or an HIV-1/-2 confirmation/differentiation test. If the test results are positive, it means that HIV antibodies or antigens were found, and the person may have HIV. If the test results are negative, it means that no antibodies or antigens were found, but it does not rule out acute HIV infection. If acute HIV infection is suspected, additional testing may be needed.