Terms You Need to Know on HIV Treatment


CD4 count is a test that measures the number of a specific type of white blood cell called CD4+ T-cells in a person's blood. These cells are important in fighting infections, but HIV attacks and kills them, weakening the immune system. The CD4 count test helps doctors monitor how HIV affects the immune system and how well the treatment works to keep the immune system healthy.


Viral load refers to the amount of HIV virus in a person's blood. The test measures the number of copies of the virus present in a milliliter of blood. Monitoring viral load is important for people living with HIV, as it helps to determine how well antiretroviral therapy (ART) is working to suppress the virus.


Undetectable refers to the level of HIV virus in a person's blood is so low that it cannot be detected by standard blood tests. Typically, this means having a viral load below 50 copies of the virus per milliliter of blood. Achieving an undetectable viral load is a primary goal of HIV treatment, as it means that the treatment is effectively suppressing the virus and preventing it from replicating in the body.


Treatment as Prevention (TasP) refers to the use of antiretroviral therapy (ART) to reduce the transmission of HIV. The idea behind TasP is that by treating people living with HIV with ART and achieving an undetectable viral load, the risk of transmitting the virus to others can be greatly reduced. This approach is supported by scientific evidence, which shows that people with an undetectable viral load are much less likely to transmit HIV to their sexual partners.