Most people have a “window period” of 3 to 6 weeks after HIV infection, during which the body is still producing antibodies to HIV, but these antibodies are not yet measurable and the infection can only be detected by nucleic acid testing, but this initial infection period is the most infectious, but HIV can be transmitted during all infection periods. After 6 weeks, i.e., after the infected person has had sufficient time to develop antibodies in the body, a retest should be performed to confirm the results of the initial test. After HIV enters the body, it takes a period of time for the blood to produce antibodies to HIV, during which time the antibodies test negative; this period is known as the window period. It is during this time that the number of HIV in the infected person’s body reaches a peak and is extremely infectious. The acute infection period also occurs during this time. Most people have a “window period” of 3 to 12 weeks after becoming infected with HIV, during which the body is still producing antibodies to HIV that are not yet detectable. After 3 months, when the infected person has had enough time to develop antibodies, a retest should be performed to confirm the initial test results.