New York State Recommendations for HIV Testing and Re-testing 1. What is the Window Period? HIV is most commonly diagnosed in adolescents and adults through HIV antibody testing. The window period is the length of time after infection that it takes for a person to develop enough antibodies to HIV to be detected by current blood or oral fluid HIV antibody tests. When an individual becomes infected, his or her body will develop antibodies against HIV. Once enough antibodies are developed, the HIV antibody test result will be positive. Most people who become infected with HIV will develop enough antibodies to be detected by current HIV antibody tests 3-6 weeks after the exposure. Each person’s body responds to HIV infection a little differently, so the window period varies slightly from person to person. It is unusual for an HIV-infected individual to not develop antibodies by 3 months after the suspected exposure. A person who tests HIV antibody negative 3 months after an exposure does not require further testing unless he/she has had repeated exposures or if the antibody test results are incompatible with the person’s clinical history.