No test can detect HIV immediately after exposure, including a blood test. The Labcorp OnDemand HIV Test is an antigen/antibody blood test. It can detect HIV infection about 18 to 45 days after exposure, which is known as the window period.3
This window period varies from person to person and also depends on the type of HIV test performed.4 If testing is done before 18 days, an HIV infection might be missed.
If the Labcorp OnDemand HIV Test is completed in the window period (earlier than 45 days after exposure) and the result is negative, you should get tested again after the end of the window period especially if there is ongoing concern about the possibility of infection.