HIV antigen testing is the fourth generation of HIV testing and can be done in the body of the infected person about 2-3 weeks after the infection, usually with the use of anti-HIV-1 core antigen P24 monoclonal antibody preparation reagents to detect the P24 antigen in the serum by ELISA, which helps in the window period of antibody production and the diagnosis of early neonatal infection. Regardless of the method of testing, once a patient is diagnosed with HIV, he or she should be treated with antiretroviral drugs as soon as possible.