Human immunodeficiency virus (HIV) is a virus that attacks white blood cells (called CD4 cells) in the immune system. These cells help your body fight infections. HIV kills CD4 cells, causing your immune system to weaken and become vulnerable to other illnesses.
Getting tested for HIV is the only way to diagnose HIV. If left untreated, HIV can cause damage to the immune system and lead to a condition called acquired immunodeficiency syndrome—commonly known as AIDS. Knowing your HIV status can get you started on treatment sooner, help you reduce symptoms, and stabilize the spread of HIV in your immune system.
There are three types of HIV tests: nucleic acid, antigen/antibody, and antibody tests. These tests may use either a sample of your blood or saliva to get results. In some cases, a provider can also use a urine sample. While some HIV tests can detect HIV sooner than others, no HIV test can detect the virus immediately after exposure. At a minimum, it can take 10 days for HIV to show up in a test result.
You can get a test for HIV at your healthcare provider’s office, family planning clinics, pharmacies, mobile testing vans, or during HIV/AIDS awareness-related community events. At-home HIV tests are also available for pick-up or purchase in some pharmacies and clinics. If you receive a diagnosis—or a positive test result—these places can connect you to specialists who provide HIV care, knowledge about treatment options, and other social services.
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Who Should Get Tested for HIV
HIV testing should be a part of everyone’s routine healthcare screening, including people who are pregnant. The Centers of Disease Control and Prevention recommend that anyone between the ages of 13 and 64 should get tested for HIV at least once. You should also get tested for HIV if you have symptoms of acute or chronic HIV.
However, not everyone experiences symptoms and symptoms of acute-stage HIV can mimic flu-like symptoms. Healthcare providers recommend frequent testing (at least once a year) for people who participate in behaviors that increase their risk of acquiring HIV.
These behaviors include:
Being a man who has sex with another manHaving sex with someone who is HIV positiveHaving unprotected vaginal and anal sexEngaging with more than one sexual partnerReceiving a separate diagnosis for sexually transmitted infection (STI), hepatitis, or tuberculosisSharing of needles, syringes, or other drug injection equipment.
Getting tested after taking part in these activities is important—as it can detect HIV early and help you get started on treatment sooner.
What Is Human Immunodeficiency Virus (HIV)? Types of HIV Tests
HIV carries an antigen called protein 24 (or just “p24”). Antigens are foreign substances that enter your body that send a signal to your immune system that there is something wrong. When your body is exposed to HIV, the immune system begins to produce antibodies (proteins that help fight the virus).
When you go in for HIV testing, your healthcare provider can offer you three tests: an antibody test, an antigen/antibody test, or a nucleic acid test (NAT). The p24 antigen shows up in HIV tests faster than the antibodies that your immune system makes to fight the antigen. That said, your provider may give you more than one test to confirm an HIV diagnosis.
Each test has a different window period. A window period is the time between when you get the virus and when an HIV test can accurately detect that you have the virus. Because of this, HIV tests cannot detect HIV immediately after you think you may have been exposed to the virus. The earliest an HIV test can detect the presence of the virus is 10 days.
Antibody Test
An HIV antibody test uses a sample of your blood, saliva, or urine to check for HIV antibodies. Most rapid HIV tests and at-home self-tests are antibody tests. This test can detect HIV antibodies 23 to 90 days after exposure to the virus.
It takes about 30 minutes to get your results from a rapid antibody test.
Antigen/Antibody Test
An HIV antigen/antibody test looks for the presence of both HIV antigens and antibodies in your immune system. This is a lab test that involves drawing blood from a vein. An antigen/antibody test can see if you have the virus 18 to 45 days after exposure to HIV.
It may take several days to get results from a traditional antigen/antibody lab test. However, rapid antigen/antibody testing is also available. With rapid testing, you can get a blood sample from a finger stick rather than your vein. But, there is a difference in the window periods and result times between rapid and traditional HIV antigen/antibody tests.
A rapid test has a longer window period than a traditional test and can detect the virus 18 to 90 days after HIV exposure. Results from a rapid antigen/antibody come faster than a traditional test—you can get rapid results in less than 30 minutes via a finger stick test.
Nucleic Acid Test
A nucleic acid test (NAT) looks for HIV in the blood. A healthcare provider takes a blood sample from your vein. They will then send the sample to a lab for proper testing. NAT results can show whether or not you have HIV and your viral load (or, how much of the virus is in your blood).
NAT has a quicker window period than other types of HIV tests. You can get a NAT test 10 to 33 days after exposure to the virus. However, it may take several days to get your lab test results back. One more thing to keep in mind: this type of test is most appropriate for people who may be showing symptoms of acute HIV and have tested negative with antibody or antibody/antigen tests.
Stages and Progression of HIV
HIV moves through three stages: the acute stage, the clinical latency (or, chronic) stage, and the AIDS (acquired immunodeficiency syndrome) stage.
Acute HIV stage: The first stage of HIV begins two to four weeks after a person acquires the virus. Most people in the acute stage experience flu-like symptoms.Clinical latency (chronic HIV) stage: The second stage of HIV can begin as soon as one month after exposure to the virus and last between 10 and 15 years. Some people in this stage don’t experience symptoms. The virus also continues to multiply at low levels in the immune system if you are not receiving treatment. AIDS stage: The third and final stage of HIV typically occurs in people who are not receiving treatment. Without treatment, the virus will continue to multiply and weaken the body’s immune system. You may experience severe symptoms such as rapid weight loss, pneumonia, and swollen lymph nodes. You are also at an increased risk of developing serious infections and cancers.
Keep in mind: HIV symptoms and how fast (or slow) you move into a different stage of HIV vary from person to person. Your HIV progression can depend on your individual symptoms, whether or not you are on treatment, and your overall health.
Diagnostic Criteria for AIDS
A person has progressed to the AIDS stage when:
The number of CD4 cells in your blood falls below 200 cells per cubic millimeter of blood (200 cells/mm3) OR, you develop one or more AIDS-defining illnesses (such as lymphoma, herpes, or cervical cancer) regardless of how many CD4 cells you have
A Quick Review
HIV is a serious chronic condition that attacks healthy white blood cells (CD4 cells) in your immune system, which can prevent your body’s ability to fight off infections. There is no cure for HIV—this is why getting HIV might feel scary. It’s OK to be nervous, but it’s also important to know that getting a diagnosis early can get you started on treatment sooner.
The only way to know your HIV status is to get an HIV test. An HIV test will use a sample of your blood (from a vein or finger stick), saliva, or urine. There are three types of HIV tests: the antibody test, the antigen/antibody test, and the nucleic acid test (NAT). Depending on the type of test you take, you can receive your results within 30 minutes or up to several days.
Getting an HIV diagnosis can be life-changing and filled with many emotions. Healthcare providers and other care specialists are there to help guide you through a positive HIV test result and the early stages of an HIV diagnosis. Your provider can also help you create a treatment plan that is right for you, which can help you live a long and healthy life with your condition.