CD4 tests is strongly recommended as the preferred method to identify advanced HIV disease among people living with HIV, said the World Health Organization (WHO). The new recommendation is part of the 2025 guidelines on advanced HIV disease. The WHO defines advanced HIV disease in adults, adolescents, and children five years and older, "as a CD4 cell count less than 200 cells/mm3".

"Advanced HIV disease is the major cause of AIDS-related deaths among people living with HIV. It is a serious public health issue, including in settings with good coverage of HIV testing and treatment, and despite having achieved or made good progress towards the 95–95–95 targets," the WHO said.