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What do HIV test results mean?

for Veterans and the Public

What do test results mean?

To understand what your test results mean, you first have to understand what kind of test is being used and what a "window period" is.

HIV tests may look for HIV antigen (part of the HIV virus) or for HIV antibodies (produced by the person's body), or may look for both. Newer testing strategies often use a combination antigen/antibody test.

The window period is the period between the time someone is first infected with the HIV virus and the time an HIV test can detect HIV infection. After someone has been infected with the virus it can take about 2 weeks for HIV antigen to be detectable with current antigen tests, and more than 3 weeks to produce enough HIV antibodies to be detected by antibody tests. In a very small number of people, the process takes up to several months.

During the window period, someone might be infected with HIV yet still test HIV-negative. Here's how that can happen. Let's say you have unprotected sex on Saturday night and become infected with HIV. On Monday, you get an HIV test. The test almost certainly will come back negative, because there is not yet enough HIV antigen or HIV antibody for the tests to detect.

Even if you go for an HIV test 2 or 3 weeks later, an antibody test result might be negative because your body still has not produced antibodies (an antigen test may be positive at an earlier time point). If you think you have been exposed to HIV, and your test results are negative, be sure to discuss this with your medical providers--they may want to test you directly for HIV virus (an HIV viral load) or to repeat a sensitive HIV antigen/antibody test.

Newer methods of HIV testing are narrowing the time of the "window period" and reducing the chance of a falsely negative HIV result.

Pop question: True or false. You can be infected with HIV and still get negative HIV test results.

Answer: TRUE. You can be infected with HIV and still get negative HIV test results. After you get infected, it can take days to a couple of weeks for the HIV virus to replicate itself and spread through the body, and 2-3 or more weeks for your body to produce antibodies to HIV. Depending on what type of HIV test is used, it may not detect HIV until between 2 weeks and several months after infection.