CD4 and HIV infectious disease: The survival rates of patients with advanced stage (stage IV) HIV infection before ART initiation (Fig 1A) and patients with a low baseline CD4 T cell count (≤200 cells/μL; Fig 1B) significantly worsened during the therapy compared with those of patients with clinical stages I–III and patients with a higher baseline CD4 T cell count (>200 cells/μL), respectively.