An 18-month-old girl with HIV returns to the clinic with her mother for ongoing care. She has no HIV-related symptoms, and the mother has regularly been giving her antiretroviral therapy medications. Her weight and height have been at roughly the 50^th percentile since birth. The child has not had any HIV-related opportunistic illnesses. The physical examination is normal, and laboratory studies show a CD4 count of 652 cells/mm³, CD4 percentage of 25%, and an HIV RNA level below the limit of detection.