If the antibody is negative for 8 weeks after high-risk contact, AIDS can be basically ruled out. After the occurrence of high-risk contact if infected with AIDS, the virus in the body needs a process of amplification, during this period of clinical examination may not be able to detect the antibody, generally 6 weeks of time, 6 weeks of negative antibody test can generally be ruled out, so the high-risk 8 weeks of negative antibodies can basically rule out AIDS. However, there are a small number of patients who will produce antibodies only after 12 weeks-6 months, without having taken blocking drugs, it is recommended to re-examine the test after 12 weeks and 6 months, and the results are still negative, before AIDS can be completely excluded. However, it is recommended to consult a physician for the actual time of testing and whether HIV infection can be ruled out. The current recommendation is to take the blocking medication as soon as possible if there is a high level of exposure, preferably taking the first dose within 24 hours, and following up with regular doses as prescribed by the physician. In addition, a nucleic acid test can be performed, usually 1 to 4 weeks after the high risk, which can also refer to whether or not one is infected with HIV.