What are the different HIV screening tests available in the U.S.?

In most cases the EIA (enzyme immunoassay), performed on blood drawn from a vein, is the standard screening test used to detect the presence of antibodies to HIV. A reactive EIA must be used with a follow-up confirmatory test such as the Western blot to make a positive diagnosis.

There are EIA tests that use other body fluids to identify antibodies to HIV. These include:

Oral Fluid Tests " use oral fluid (not saliva) that is collected from the mouth using a special collection device. This is an EIA antibody test similar to the standard blood EIA test and requires a follow-up confirmatory Western Blot using the same oral fluid sample.

Urine Tests " use urine instead of blood. The sensitivity and specificity (accuracy) are somewhat less than that of the blood and oral fluid tests. Reactive test results must be confirmed with a blood-based Western Blot.

Home testing kits:

Can be purchased in most pharmacies and via the Internet and involve no actual testing of the blood by the person using the kit. The only ..."at-home components of the testing process involve the collection of a small sample of blood using a finger stick and the receipt of the results over the phone. First, the blood sample is mailed to the manufacturer for a standard EIA test. The consumer must call a phone number several days later to receive the results and be offered the choice of speaking to a trained counselor. A positive result must be confirmed with a blood-based Western Blot (which cannot be done with a home-based test kit).

Rapid tests:

A rapid test is a screening test that produces very quick results, in approximately 20-60 minutes. In comparison, results from the other more commonly used HIV antibody screening test, the enzyme immunoassay (EIA), are not available for several days to a few weeks.

Both the rapid test and the EIA look for the presence of antibodies to HIV. As is true for all screening tests, a reactive rapid HIV test result must be confirmed with a follow-up confirmatory test before a final diagnosis of infection can be made.

More on rapid HIV testing...

There are other tests that are used in screening the blood supply and for rare cases when standard tests are unable to detect antibodies to HIV.

For additional information on the various types of HIV tests, visit the Food and Drug Administration (FDA) Center for Biologics Evaluation and Research at http://www.fda.gov/cber/products/testkits.htm

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Centers for Disease Control & Prevention
National Center for HIV, STD, and TB Prevention
Divisions of HIV/AIDS Prevention