Four weeks after a history of high-risk exposure, HIV antibody testing can be 98% accurate. However, it is usually necessary to repeat the test once to completely exclude it. After the fourth week the test result is negative, you can basically judge that you are not infected with AIDS, but at this time the negative result can not completely exclude the infection of HIV (human immunodeficiency virus), it is recommended that in the sixth week and three to six months to do the test again for HIV-specific antibodies, if they are all negative can be excluded from the HIV virus infection. After entering the human body, HIV stimulates the body’s immune system to produce specific antibodies. The third generation of HIV antibody test reagents used in most hospitals and CDCs in China have a window of 21 days after a history of high-risk exposure. Four weeks after the history of high-risk exposure to HIV, the results of the specific antibody test can basically determine whether or not the infection, but in daily life, if there is a history of high-risk exposure, it is important to go to the outpatient clinic of the infection department of the local hospital in a timely manner, to consult the relevant information, and if necessary, to take the relevant blocking measures.