What can you expect during HIV testing?

Traditional HIV testing

The enzyme-linked immunosorbent assay (ELISA) test looks for antibodies to the virus in a sample of your blood drawn from a vein. If this test is positive — meaning you have antibodies to HIV — the same test is repeated. If the repeat test is also positive for HIV antibodies, you need a confirming blood test called the Western blot test, which checks for the presence of HIV proteins. The Western blot test is important because you may have non-HIV antibodies that cause a false-positive result on the ELISA test. Combining the two types of tests helps ensure that results are accurate, and you receive a diagnosis of HIV only if all three tests are positive.

It can take up to two weeks to get the results of the ELISA and Western blot tests.

Rapid HIV testing
Several rapid tests offer highly accurate information within as little as 20 minutes. These tests also look for antibodies to the virus using a sample of your blood, drawn from a vein or a finger prick, or fluids collected on a treated pad that's rubbed on your upper and lower gums. The oral test is almost as sensitive as the blood test and eliminates the need for drawing blood. A positive reaction on a rapid test requires a confirming blood test. And because the tests are relatively new and were originally approved for use only in certified laboratories, they may not be available everywhere.

Home HIV testing
Currently, the Food and Drug Administration (FDA) has approved only one HIV test for home use. The Home Access HIV-1 Test System, marketed by Home Access Health, is as accurate as traditional HIV tests, and all positive results are automatically retested.

For this test, you mail in a drop of your blood, then call a toll-free number to receive your results in three to seven business days. This approach ensures your privacy and anonymity — you're identified only by a code number that comes with your kit. The greatest disadvantage is that you're not offered the counseling that you typically receive in a clinic or doctor's office, although you're given referrals to medical and social services.

Early detection HIV testing
Some tests can detect HIV infection earlier, before antibodies are detectable in standard HIV testing. These tests may cost more than standard HIV testing and may not be as widely available. You will also still need standard antibody testing later, to confirm results, because false-positives and false-negatives are possible. Tests that can help identify early HIV infection include:

• PCR or RNA tests. Polymerase chain reaction (PCR) tests involve evaluating a blood sample for genetic material — RNA or DNA — produced by the HIV virus infection. These tests measure the amount of virus present in your blood (viral load) and are most useful for monitoring your condition after you've already been diagnosed with HIV. The tests may return a false-negative result if infection with HIV occurred too recently, such as fewer than five days ago.
• p24 antigen tests. This test can identify an HIV protein — p24 — in your blood from about one week to up to three or four weeks after infection with HIV. Once antibodies begin to form, they bind to the p24 protein, making p24 undetectable. By that time, standard antibody tests may be able to detect the antibodies.