What Is HIV? How Do HIV Tests Work?
HIV stands for Human Immunodeficiency Virus. It is a retrovirus that targets the body’s immune system. Without treatment, it can progress to AIDS (Acquired Immunodeficiency Syndrome). Unfortunately, there is currently no definitive cure for HIV. It is primarily transmitted through blood and body fluids.
Why Should I Get Tested for HIV?
As mentioned earlier, HIV has no cure. Once infected, a person has it for life. HIV is classified as a sexually transmitted infection, but it can also spread through other means such as:
- Blood transfusions
- Shared or contaminated syringes
- Transmission from an infected mother to her baby during pregnancy, childbirth, or breastfeeding
Early detection and proper medical care can help individuals with HIV live healthy lives while preventing transmission to others.
HIV Tests
It is important to note that being HIV-positive is not the same as having AIDS. Some individuals may remain asymptomatic for years despite being HIV-positive. The only way to confirm an HIV infection is through testing. Various types of HIV tests are available.
HIV Screening Tests
There are three main types of HIV screening tests. These tests analyze blood (from a vein or finger prick), urine, or saliva. The speed at which these tests detect the virus depends on their window period—the time between exposure to the virus and when it becomes detectable in the body.
- HIV Antibody Test: These tests detect antibodies produced by the immune system in response to HIV. The window period for antibody tests is 23–90 days. They are available as rapid tests, home self-testing kits, and laboratory tests.
- HIV Antigen and Antibody Test: These tests look for both antigens (viral proteins that trigger an immune response) and antibodies. The window period is 18–90 days for rapid tests and 18–45 days for laboratory tests. These are also available as rapid tests, home self-testing kits, and laboratory tests.
- Nucleic Acid Test (NAT): NAT detects the actual virus in the blood. These tests are expensive, labor-intensive, and conducted in a laboratory. The window period for NAT is 10–35 days.
Oral HIV Tests
At-home HIV self-testing kits fall under this category. These over-the-counter tests use a saliva swab to detect HIV antibodies. Results are typically available within 20 minutes. A positive or negative result from an oral test is not definitive and requires follow-up testing in a clinical setting.
PCR HIV Tests
PCR tests are a type of nucleic acid test that detects HIV genetic material (RNA) in the sample. They are highly sensitive, expensive, and require a laboratory setting. PCR tests are often used to screen or measure viral loads in high-risk cases.
Early HIV Tests
Early HIV tests, also known as rapid tests, primarily detect HIV antibodies. Newer versions, referred to as 4th-generation tests, detect both viral antigens and antibodies. These tests are highly effective and can detect HIV infection faster than earlier generations. Early HIV tests typically use a finger-prick blood sample.
HIV Test Results
After taking an HIV test, you will receive either a positive or negative result:
- Positive HIV Test Result: If you take an at-home test and receive a positive result, contact a healthcare provider for follow-up testing to confirm the diagnosis. If tested at a clinic or community health center, follow-up tests will usually be conducted automatically.
- Negative HIV Test Result: If you receive a negative result, it is essential to consider the window period. Retest after the window period has passed to ensure accuracy. If the second test is also negative, you are not infected with HIV.
HIV Test Accuracy
Modern HIV tests are highly accurate. By 6 weeks, 4th-generation tests can detect 99% of infections. Testing earlier than 4 weeks reduces the detection rate to about 95%. Therefore, any positive result should always be followed by confirmatory laboratory testing.