HIV antibody testing is used to determine whether or not a person is infected with HIV. Early treatment of HIV infection and immune system monitoring can greatly improve long-term health. Also, knowing your HIV status may help you change behaviors that would put you and others at risk.

Antibodies to the HIV virus can be detected by a screening test called an ELISA. The ELISA test is repeated if positive. The ELISA method is very sensitive but requires another test, a Western Blot, to confirm the results because false positives can occur. These tests can be done on a blood sample in a doctor’s office or a local clinic. There are also currently approved home test kits available for HIV antibody testing. These allow you to take a sample of your blood from a finger at home and mail it to a testing center. You would then hear your results later over the phone, along with appropriate counseling. There are, however, no available tests that can be performed at home.

Antibody testing for HIV should be ordered if you think you may have been exposed to HIV. Testing is recommended if:

• You are sexually active (three or more sexual partners in the last 12 months).
• You received a blood transfusion prior to1985, or a sexual partner received a transfusion and later tested positive for HIV. For more information, go to: http://www.cdc.gov/hiv/pubs/faq/faq15.htm
• You are uncertain about your sexual partner’s risk behaviors.
• You are a male who has had sex with another male.
• You have used street drugs by injection, especially when sharing needles and/or other equipment.
• You have a sexually transmitted disease (STD).
• You are a health care worker with direct exposure to blood on the job.
• You are pregnant. (There are now treatments that can greatly reduce the risk that a pregnant woman who has HIV will give the virus to her baby.)
• You are a woman who wants to make sure you are not infected with HIV before getting pregnant.

A healthy individual has no antibodies to HIV. If you test positive for HIV antibodies on both the ELISA and the Western Blot tests, you are considered to be infected with HIV.

Antibody testing will not detect HIV immediately after exposure, during the window before the development of antibodies. If you are tested too soon, your result may be negative despite the fact that you are infected (false negative). Because of this, repeat testing is important. You should have another HIV antibody test in 3–6 months from the time of a possible exposure to the virus.