CD4 cell counts are used, together with the viral load test, to get a complete picture of how the immune system is fighting the virus. The amount of CD4 cells and viral load levels will also guide a patient and their doctor in deciding when to start antiviral medication. The goals are to keep CD4 count high and viral load low. Therefore, monitoring CD4 counts and HIV-1 viral load levels before and during treatment will help a doctor assess how well their patient is responding to their prescribed therapy.