Information on the HIV Blood Test

Information on the HIV Blood Test
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How It Works

Blood for the HIV test can be taken as a prick on your finger, but it is usually drawn from a vein in your arm. Often this blood is sent away to a lab for testing, but it can be done rapidly for quick results.

The blood is tested for antibodies against HIV, not the HIV virus itself. An antibody is a protein produced by the immune system in response to an antigen, or a potentially harmful foreign molecule in the body. The presence of an antibody in your blood or other bodily fluid means that you’ve been exposed to the antigen at some point. The HIV blood test looks for antibodies against the virus in your blood to determine whether or not you’ve been infected with the virus.

The blood sample is tested using EIA (enzyme immunoassay). This means that the blood sample is added to a solution with antigens that will bind specifically to HIV antibodies. If the antibodies are present in the blood, antigens and antibodies will bind and cause a reaction with enzymes in the solution. This reaction causes a color change, which in turn signifies the presence of the HIV antibodies.

Who Should Get Tested?

Any sexually active person should get tested for STDs (sexually transmitted diseases) and HIV regularly, particularly if he or she has multiple partners or isn’t consistently using condoms. You can also seek out the test if you feel it is necessary or if you would just like to know your status. If you think you may have been exposed to the HIV virus, whether through unprotected sex, intravenous drug use, or other sharing of bodily fluids with an infected person, you should get tested. Many STDs, including HIV, don’t immediately show symptoms, so you may be infected even if you feel completely healthy. It is important to note, however, that since the test looks for antibodies and not the actual virus, it is necessary to wait about three months from potential exposure to get more accurate results.

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Where to Get Tested

Your primary care doctor can order a HIV blood test for you, which can then be done on the premises or wherever blood work is typically done. Your doctor may not suggest the test unless you ask for it, so be sure to voice your concerns and ask for the blood test.

Family planning clinics, such as Planned Parenthood, offer low-cost HIV and STD screenings. Local health departments also offer HIV and STD testing services. If you are a college student, be sure to check out your student health services for free or low-cost HIV and STD tests. Many other clinics offer confidential or anonymous HIV testing services, so be sure to look at the resources available in your community.