The best time to test for HIV is usually within six weeks after infection. After the human body is infected with HIV until HIV antibodies can be detected in peripheral blood, the period is called the window period, China has now shortened the window period to two weeks, and it is currently believed that the optimal time for testing is from two weeks to about six weeks, while the internationally recognized window period is six months. Because HIV replicates in the body for a period of time after infection with HIV, and it takes a period of time for the body to produce HIV antibodies, the period of time from infection with HIV to the time when HIV virus or HIV antibodies can be detected is called the window period. However, the length of the window period varies depending on the individual’s physical condition and the sensitivity of the test method and reagents used.