This includes predicting disease progression, providing a basis for initiating antiviral therapy, assessing treatment effects, guiding treatment regimen adjustment, and also serving as a reference indicator for early diagnosis of HIV infection. Diagnosis of HIV infection in infants <18 months of age can be made by nucleic acid testing, with 2 positive nucleic acid test results as a reference basis for diagnosis, which will be confirmed by antibody testing after 18 months of age. HIV viral load test results below the detection limit, reporting the results of this test below the detection limit, is seen in individuals without HIV infection, receiving successful antiviral therapy or the body itself can effectively inhibit viral replication of some HIV-infected patients. HIV viral load test results above the detection limit can be used as an auxiliary indicator for the diagnosis of HIV infection, and cannot be used for the diagnosis of HIV infection alone.