CD4 and viral load: two essential blood tests

Your CD4 and viral load are the main blood tests after you are diagnosed.

After starting ART, the viral load test is more important for making sure ART is working well.

CD4 count

The CD4 count tells you about your immune system.

  • Results are given as cells per cubic millimetre (cells/mm3).
  • The range for HIV negative adults is from about 400 to 1600. Getting above 500 is considered normal.
  • Even with a very low CD4 count, ART can boost your immune system much higher.
  • The CD4 percentage (CD4%) is also good to know in case your CD4 count has unexpected changes. The normal range is from about 25 to 60% with the average about 40%.

Viral load

Viral load is the main monitoring test for people on ART.

  • This test shows how much virus is in a small sample of blood. Results are given as copies of the virus per millilitre (copies/mL).
  • It also shows how well ART is working. The aim is to reduce this to less than 50 copies/mL. This is called undetectable.
  • If viral load doesn’t become undetectable within 1 to 3 months – or if it increases later – you might need to change treatment. This is because the drugs might not be working or you may not be taking them correctly.

Last updated: 1 June 2022.