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CD4 & Viral Load

When first diagnosed you will hear a great deal about CD4 and Viral Load.

  • CD4 measures how well your immune system is functioning.    
  • Viral Load measures how much virus is in your body.


  • Measures the strength of the immune system by counting how many CD4 cells are present in a cubic ml of blood    
  • A healthy immune system is usually 350 and above    
  • When the CD4 fall to below 350 you will usually be advised to start medication    
  • CD4 will be reflective of general health    
  • CD4 percentage is the percentage of white blood cells (lymphocytes) that are CD4 cells.    
  • 30% – 66% of white blood count is normal    
  • CD4 ceases to be important once you have started medication and become undetectable.

Viral Load  

  • Measures the amount of virus present in a cubic ml of blood.    
  • Also in semen – including precum – vaginal fluid and breast milk    
  • The lower the viral load the less strain on the immune system – and the less transmissible    
  • The goal of medication is to reduce viral load to less than 50 copies in a ml of blood    
  • Under 50 copies in a cubic ml of blood = UNDETECTABLE

What does UNDETECTABLE mean?    

  • A healthy immune system    
  • Normal life expectancy    
  • No transmission risk    
  • Reduced risk of ill health regarding HIV    
  • Reduced risk of mother to child transmission in pregnancy and breastfeeding    
  • You can be employed in more of less any job    
  • Protection under the law

For more information use the NAM website:

If you have any further questions, please talk to your consultant, doctor, nurse, health advisor or The Peer Support workers