Early detection of HIV is usually done by blood tests for HIV antibodies, and some patients in the early stages can be diagnosed with HIV-RNA and P24 antigen. Of course, because many patients are in the window period at the early stage of HIV infection, blood tests for HIV antibodies may be negative and not easily detectable. For high-risk groups, it is recommended to retest again after the window period, and if the HIV antibody is still negative, it is ruled out. For some of the HIV antibody positive, further confirmatory tests are required, and only a positive confirmatory test can clearly diagnose HIV infection.