Testing for HIV
Types of HIV Tests and Their Accuracy
Testing for HIV involves providing either a blood or an oral fluid sample. Healthcare providers use three different types of tests to diagnose HIV:
- HIV antibody tests. These tests search for antibodies to HIV in the oral fluid or blood. Antibody tests can usually detect HIV 23 to 90 days after exposure.
- HIV antigen/antibody tests. A combined antigen/antibody test detects antigens (immune system activators) and HIV antibodies. The presence of antigen p24 indicates HIV. The testing window for antigen/antibody tests is 18-90 days following exposure.
- HIV nucleic acid tests. Nucleic acid tests (NAT) locate the RNA (genetic material) of HIV. This type of test can also diagnose viral load (i.e., the amount of virus in your blood). NATs require lab testing of a blood draw from the patient’s vein. NATs may detect HIV ten to 33 days past exposure.
Although nucleic acid tests can detect HIV presence faster than other types of tests, they’re also more expensive. Because of the comparatively high cost of NATs, healthcare providers will typically recommend this test to people who have had recent exposure to the virus and show early HIV symptoms but got a negative result with another type of test.
Screening for HIV will typically start with an antibody or antigen/antibody test. Patients who test positive will undergo follow-up testing to verify the diagnosis.
HIV Test Accuracy
In general, all modern HIV tests have accuracy levels of 99% or more. However, all tests have what’s known as a “window period,” meaning the time that passes between exposure and the point when a test can detect HIV. Testing too early may give a false negative result. A test will always be more accurate after the end of the window period.
False positives are rare but may occasionally happen if samples get mislabeled, or a laboratory worker misinterprets test results.
You can undergo HIV screening in health clinics, community health centers, family planning clinics, and specialized sexual health clinics or testing centers. Many people choose the latter for the high level of privacy such STD-focused services usually offer. With Rapid STD Testing, you also have the advantage of 2,500+ centers nationwide, so you’re sure to find a convenient location near you.