After HIV infection, it generally takes 2 to 12 weeks to produce a sufficient amount of antibodies to be detected by clinical tests. The period from the time of infection to the time when HIV antibodies can be detected in the blood is called the “window period”. The “window period” is usually about 3 months. If the HIV antibody test is done during the “window period”, the result may be “negative” and the test will need to be repeated after 3 months. Feng Zhihong, Department of Dermatology