The window period for an HIV test refers to the time between HIV exposure and when a test can detect HIV in your body. During this period, someone can be very infectious but still test HIV negative. The window period depends on the type of HIV test used. Different types of tests have different window periods:

• Antibody tests: These tests can usually detect HIV 23 to 90 days after exposure. Most rapid tests and self-tests are antibody tests.

• Rapid antigen/antibody test: This test done with blood from a finger stick can usually detect HIV 18 to 90 days after exposure.

• Antigen/antibody lab test: This test using blood from a vein can usually detect HIV 18 to 45 days after exposure.

• Nucleic acid test (NAT): This test can usually detect HIV 10 to 33 days after exposure. NATs can detect HIV in your body the soonest after infection. The test looks for the virus in your blood. You need a certain amount of the virus in your blood before the test will detect it. This is called your viral load. You can get a negative test if your viral load is still low. A NAT can tell you if you have HIV as early as 7 to 28 days after infection.

The window period of modern laboratory HIV tests is 45 days. The window period of rapid, point-of-care tests and self-tests is 90 days. However, HIV window periods can vary, and it is hard to say exactly how long the window period lasts, as there are variations between individuals. If you get an HIV test after a potential HIV exposure and the result is negative, get tested again after the window period for the test you took.