I have seen advertisments for rapid HIV test such as DISCRET. Can you tell if the claims that they can detect HIV after 28 days are correct or if this only for certain people.Is this type of test any different from the ELISA test.Will I save any time from having one of these test done or do I have to wait for twelve weeks?
Please, please be careful of claims that advertisers make about HIV testing, especially if they are asking for money from you. In the United States, testing kits need to be approved by the Food and Drug Administration (FDA) before they can be legally used. There are some "organizations" marketing and selling fraudulent tests (see FDA warning http://www.ftc.gov/opa/1999/9911/cyberlinx.htm).
As far as I know, there is only one rapid test that has been approved by the FDA, and has limited availability in public health clinics around the country. The only approved rapid test is referred to by its acronym SUDS and is manufactured by Murex. Other rapid tests are currently being reviewed by the FDA.
A rapid HIV-1 test is an antibody screening test that can have results available to the client within 15-30 minutes. Like the EIA/ELISA, it is a highly sensitive test that screens for HIV antibodies. This means that the window period still applies; rapid screening is only meaningful after three months have elapsed. The 28 day mark refers to the AVERAGE amount of time it takes someone to develop a detectable level of antibodies after infection.
A negative rapid test after the window period has elapsed means that you are HIV negative; no confirmatory test is needed because of the test's 100% sensitivity. A positive rapid test requires confirmatory testing (Western Blot/IFA) since the test lacks adequate specificity. This is a major drawback to rapid testing because some clients may get a positive/reactive rapid test result and need to wait for confirmatory screening to be conducted, which usually takes up to one week. A rapid test counselor will talk with you about this possibility and its ramifications.
Rapid tests are expensive as well, so you may have to pay for it. However, the higher cost balances out when you take into account the number of people that don't return for standard antibody testing results. Read through the CDC article "Rapid HIV tests" (http://www.cdc.gov/hiv/pubs/rt/rapidqas.htm) for more information.