The antigen of HIV refers to the P24 antigen of HIV, which can be detected in the body of an infected person about 2-3 weeks after infection, and can therefore be tested in the hospital about 3-4 weeks after a high-risk behavior. If the appropriate antigen is detected at this time, the diagnosis can be confirmed. For a final diagnosis, a confirmatory test should be performed, which uses a protein blot to detect the presence of HIV antibodies in the patient’s body. Once a patient is diagnosed with HIV, he or she should be treated with antiretroviral drugs as soon as possible to avoid progression to the AIDS stage.