The only way to know for sure if you have HIV is to get a blood test. It usually takes 1 - 2 weeks for test results to come back from the laboratory. There are 2 common types of tests for HIV that are performed in British Columbia.
The first type of test is called an antibody test. If you have been exposed to HIV, your immune system will make antibodies to try to destroy the virus. The two primary blood tests used to detect HIV antibodies are called the ELISA and the Western Blot assay. If the first ELISA is positive, the blood sample is tested again. If the second ELISA test is positive, the lab will do a Western Blot to confirm.
The second type of test is called a nucleic acid amplification (NAAT) test. This test detects genetic material belonging to the HIV virus (DNA and RNA) in the blood. If viral RNA is detected but antibody tests are negative or unclear, it means that the person may be in the acute or very early stages of HIV infection.
The time it takes for a new HIV infection to show up in a blood test is called the "window period". During this time the infection is not yet detectable but can still be passed on to other people. The window period for the antibody test ranges from 4 - 6 weeks up to 3 months, as it takes this long for HIV antibodies to reach a detectable level in the body.
HIV testing is done in most doctors’ offices, public health units, hospitals, and clinics.
Some doctors and clinics in British Columbia now also use a Point of Care HIV test. This is an ELISA (antibody) test that can be performed in the office or clinic, and the results are ready in about 15 minutes. However, these results are preliminary only - any positive tests must be confirmed with a Western Blot test performed at the provincial laboratory.
If you think you have been exposed to HIV but you test negative for it:
- another HIV test can be performed 2 - 3 weeks after possible exposure.
- meanwhile, take steps to prevent the spread of the virus.