In most cases the enzyme immunoassay (EIA) used on blood drawn from a vein, is the most common screening test used to look for antibodies to HIV. A positive (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 look for antibodies to HIV. These include:
Oral Fluid Tests
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. A follow-up confirmatory Western blot uses 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. This is also an EIA antibody test similar to blood EIA tests and requires a follow-up Western blot using the same urine sample.
A rapid test is a screening test that produces very quick results, in approximately 20 minutes. Rapid tests use oral fluid or blood from a vein or finger stick to 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 can be made. These tests have similar accuracy rates as traditional EIA screening tests.
Home Testing Kits
Consumer-controlled test kits (popularly known as "home testing kits") were first licensed in 1997. Although home HIV tests are sometimes advertised through the internet, currently the Home Access HIV-1 Test System is approved by the Food and Drug Administration (FDA) - the accuracy of other home test kits cannot be verified. Each kit comes with specific instructions on how to collect a sample, how to send it to an accredited laboratory, and how to receive test results. Every part of the process is done anonymously.
Customers may speak to a counselor before taking the test, while waiting for the test result and when the results are given. All individuals receiving a positive test result are provided referrals for a follow-up confirmatory test, as well as information and resources on treatment and support services. The Home Access HIV-1 Test System can be found at most local drug stores and online.
RNA tests look for the genetic material of the virus and can be used in screening the blood supply and for the detection of rare very early infection cases when antibody tests are unable to detect antibodies to HIV.