The time between when a person may have been exposed to
HIV and when a test can tell for sure whether they have the virus is called the window period. The window period varies from person to person and depends on the type of test used to detect HIV. Ask your health care provider or test counselor about the window period for the test you’re taking.
A nucleic acid test (NAT)can usually tell you if you have HIV infection 10 to 33 days after an exposure.
An antigen/antibody test performed by a laboratory on blood from a vein can usually detect HIV infection 18 to 45 days after an exposure. Antigen/ antibody tests done with blood from a finger prick can take longer to detect HIV (18 to 90 days after an exposure).
Antibody tests can take 23 to 90 days to detect HIV infection after an exposure. Most rapid tests and self-tests are antibody tests. In general, antibody tests that use blood from a vein can detect HIV sooner after infection than tests done with blood from a finger prick or with oral fluid.
If you get an HIV test after a potential HIV exposure and the result is negative, get tested again after the window period. Remember, you can only be sure you are HIV-negative if:
Your most recent test is after the window period.
You haven’t had a potential HIV exposure during the window period. If you do have a potential exposure, then you will need to be retested.