HIV-1 Antibody Test (ELISA and Western Blot)

What is the HIV-1 antibody test?

The HIV-1 antibody test checks for antibodies to the most common type of the human immunodeficiency virus (HIV-1). HIV is the virus that causes AIDS (acquired immunodeficiency syndrome), a life-threatening disease. If you are infected with HIV, your immune system makes a type of protein called an antibody to try to destroy or get rid of the virus.

There are different HIV antibody tests. One test is the ELISA (enzyme-linked immunosorbent assay). If the ELISA test is positive, a second test called a Western blot is done to confirm the result. The Western blot takes longer to perform and is more expensive than the ELISA test, but it is more precise.

There is no way to know, without testing, if you are infected with HIV. Learning whether you are HIV positive will help you care for yourself and protect your loved ones.

Why is this test done?

This test is done to see if you are infected with the virus that causes AIDS. This test is also used to screen donated blood for HIV.

How do I prepare for this test?

It is important to get counseling before you have the HIV test. This can help to identify things you do that may increase your risk for HIV infection.

How is the test done?

Usually a small amount of blood is taken from your finger or your arm. Blood from a finger prick is put in a vial of solution and tested with a dipstick. Blood taken from your arm with a needle will be sent to a lab for testing. Some hospitals and clinics may instead test a sample of fluid obtained from your mouth by swabbing your gums.

Having the test takes just a few minutes of your time. There is no risk of getting AIDS, hepatitis, or any other blood-borne disease from this test.

Home test kits have become available through the Internet. However, some of these tests have been shown to be inaccurate. The only HIV test approved by the FDA is the Home Access HIV testing kit. When you do this home test, first you register by phone. Then you collect a sample of blood and mail the sample to the lab for testing. Toll-free telephone support is available 24 hours a day for test and result questions. Like the positive results from the first HIV tests done by your healthcare provider, positive results from a home test need to be confirmed with more testing by your provider.

How will I get the test result?

Ask your heath care provider when and how you will get the result of your test. Results from the finger-prick or gum-swabbing HIV tests may be available in 30 minutes or less. You may get results from other HIV tests in 2 to 10 days.

The test results are confidential. Confidential testing ensures that your results will be guarded with care. Positive results may be reported by name to the health department for 2 reasons. The first reason is to provide help with partner notification and referral to care. The second is to provide reports to the federal government so there can be a count of how many people have HIV. The count helps determine how much money each state needs for HIV care.

Some centers offer anonymous testing. Anonymous testing does not use your name at all. Positive results are reported without any personal identifiers. Some people feel this better protects the confidentiality and civil rights of people who test positive for HIV.

What do the test results mean?

In general, a positive HIV test means that you are infected with HIV, and a negative test means that you are not infected with HIV. The test does not directly measure or identify the HIV virus in the blood, however. Instead it measures antibodies that the body makes in response to the viral infection. Because it takes at least a few weeks for the antibodies to appear in the blood after infection by the virus, it is possible to have a negative test if you have been recently infected (this is called a false negative test). In this case, the test will become positive if it is repeated several weeks or months later. If you have a negative test result but you are in a high-risk group, you may need to have another test in 3 to 6 months. Most people test positive 6 weeks after infection.

Sometimes an HIV test result can be positive even though you do not have HIV infection (this is called a false positive test). For this reason, when a positive result occurs, labs do a second HIV test (Western blot) to check the result.

What if my test result is positive?

If your first test for HIV is positive, you should have more blood tests to confirm the results. If repeat tests are positive, you should seek medical care, even if you have no symptoms. In some cases you may need to start taking medicine to try to stop the HIV infection from developing into AIDS. You need to discuss the test results with your healthcare provider or an HIV counselor as soon as possible to protect your health and the health of people you love.