Does this test have other names?
HIV test; human immunodeficiency virus antibody test, type 1, HIV p24 antigen
What is this test?
The test looks for HIV-1 antibodies in your blood.
Your body makes these antibodies when you have been exposed to HIV, the virus that
All tests for HIV antibodies will look for HIV-1, which is more common than HIV-2
in the U.S. Combination tests have been developed to find HIV antibodies and HIV
antigens called p24 antigens. The HIV antibody test recommended by the CDC is the
HIV-1/2 antigen/antibody combination immunoassay test.
If you test positive for HIV, the CDC recommends the following follow-up tests:
HIV-1/HIV-2 antibody differentiation immunoassay. This test is to confirm HIV and find out whether you have HIV-1 or HIV-2.
HIV-1 NAT (nucleic acid test). You will need this test to confirm the HIV-1 infection if you test positive on the
first antigen/antibody combination immunoassay test and negative or undetermined on
the antibody differentiation immunoassay.
Other follow-up tests such as ELISA (enzyme-linked immunosorbent assay) and Western
blot may still be used but are not as common as they used to be.
Why do I need this test?
You may have this test if you have symptoms of an HIV-1 infection. Early symptoms
are flu-like and include:
Runny or stuffy nose
You may also have this test if you've had unprotected sex and want to find out if
you are HIV-positive. Testing is important to protect yourself and others, since you
can be infected with the virus even if you don't feel sick. Men who have sex with
men should be tested every 3 to 6 months.
You may have this test if you have shared needles to inject drugs. Needle-sharing
has been linked with the spread of HIV infections.
You may also have this test if you are diagnosed with a different sexually transmitted
infection (STI). This is because STIs generally suggest the possibility of high-risk
You may have this test if you are pregnant. Pregnant women should be tested with each
pregnancy, even if the testing was negative with earlier pregnancies.
You may also have this test if you are a healthcare worker who has been stuck by a
contaminated needle or instrument. You should be checked at the time of the exposure
and at 6, 12, and 24 weeks.
What other tests might I have along with this test?
Your healthcare provider will also order a Western blot test if your ELISA test is
positive. Your provider may also order viral load testing if he or she suspects you
have an acute HIV infection.
What do my test results mean?
Many things may affect your lab test results. These include the method each lab uses
to do the test. Even if your test results are different from the normal value, you
may not have a problem. To learn what the results mean for you, talk with your healthcare
If you test positive for HIV on this test, you will need one of follow-up tests to
confirm that you have an HIV infection.
Depending on your results, your healthcare provider may suggest that you speak with
an HIV counselor.
How is this test done?
The test requires a blood sample, which is drawn through a needle from a vein in your
Does this test pose any risks?
Taking a blood sample with a needle carries risks that include bleeding, infection,
bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight
stinging sensation or pain. Afterward, the site may be slightly sore.
What might affect my test results?
Timing is important. It takes time for your body to make antibodies after you are
exposed to a virus like HIV. Taking the test too soon after exposure can give a false
negative. Most people will make antibodies 3 to 12 weeks after being infected
How do I get ready for this test?
You don't need to prepare for this test.