What Are the Types of HIV Tests?
There are three main types of HIV tests:
- antibody tests
- combination tests (antibody/antigen tests), and
- nucleic acid tests (NATs)
How soon each test can detect HIV infection differs because each test has a different window period. The window period is the time between when a person gets HIV and when a test can accurately detect HIV infection.
If you think you may have been exposed to HIV, get tested! Testing is the only way to know for sure if you have HIV.
Read about the three types of HIV tests below.
Most HIV tests, including most rapid tests and home tests, are antibody tests. Antibody tests check for HIV antibodies in blood or fluids from your mouth. HIV antibodies are disease-fighting proteins that the body produces in response to HIV infection.
It can take 3 to 12 weeks for your body to make enough antibodies for an antibody test to detect HIV infection. (In other words, the window period for antibody tests in most people is somewhere between 3 to 12 weeks from the time of infection.)
With a rapid antibody test, results are ready in 30 minutes or less. For information on home tests, see below.
Combination Tests (Antibody/Antigen Tests)
Combination tests (also called antibody/antigen tests) can detect both HIV antibodies and HIV antigens (a part of the virus) in your blood.
A combination test can detect HIV infection earlier than an HIV antibody test can. It can take 2 to 6 weeks for your body to make enough antigens and antibodies for a combination test to detect HIV infection. Combination tests are now recommended for HIV testing that’s done in labs, and they are becoming more common in the United States. However, not all testing sites offer this test by default; if you think you have been recently exposed to HIV, be sure to let your provider know and ask if a combination test is available.
Nucleic Acid Tests (NATs)
Nucleic Acid Tests (NATs) look for HIV in the blood.
NATs can detect HIV infection about 7 to 28 days after you have been infected with HIV. NATs are very expensive and not routinely used for HIV screening unless you had a high-risk exposure or a possible exposure with early symptoms of HIV infection.
Will I Need a Follow-up HIV Test?
Your initial HIV test will usually be either an antibody test or a combination test. Then:
- If your initial test result is negative and the test was done during the window period, you should get re-tested at the end of that window period, usually 3 months after the possible exposure to HIV. Until that time, you should continue to take actions to prevent HIV, like using condoms the right way every time you have sex and taking medicines to prevent HIV if you’re at high risk. If your follow-up test is also negative, continue to take actions to prevent HIV and talk to your healthcare provider about how frequently you should get tested in the future.
- If your initial test result is positive for HIV infection, follow-up testing will be done to make sure that the diagnosis is correct.
How Long Does It Take to Get the Results of an HIV Test?
Rapid HIV tests can produce results within 30 minutes. For other HIV tests, it usually takes a few days to a few weeks to get results.
Home HIV Tests
There are two HIV tests approved by the U.S. Food and Drug Administration (FDA) for home use. Both are HIV antibody tests. These two tests are available for purchase in stores and online. They may be used at home, or they may be used for testing in some community and clinic testing programs.
The Home Access HIV-1 Test System is a home collection kit, which involves pricking the finger for a blood sample, sending the sample to a licensed lab for testing, and then calling the lab for results as early as the next business day. If the result is positive for HIV, the lab will do a follow-up test on the same blood sample to confirm the initial HIV-positive test result. This test is anonymous. The manufacturer provides confidential counseling and referral to treatment.
The OraQuick In-Home HIV Test comes with a test stick and a tube with a testing solution. You use the test stick to swab your mouth to get a sample of oral fluids. To get results, you insert the test stick into the test tube. Test results are ready in 20 minutes. A positive result on this home HIV test must always be confirmed by additional HIV testing performed in a health care setting. The manufacturer provides confidential counseling and referral to follow-up testing sites.
Last revised: 03/07/2017