2 Virology, HIV and viral load

2.12 Viral load on and off treatment

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Viral load when not on treatment

When not taking ARVs, CD4 count is more important than viral load.

Viral load tests are still useful, but they are not as important at either predicting the risk of infections or when you should start treatment.

The one exception may be if your viral load is very high. If your viral load is over 100,000 or perhaps over 500,000, this would be seen as a reason to start treatment at a higher CD4 count than 200 of 350 cells/mm³.

Viral load is higher in children than in adults when not using ARV treatment, but it is just as important for children on treatment to reduce their viral load to less than 50 copies/mL.

Viral load when on treatment

If you are using HIV treatment, viral load is more important than CD4 count.

This is because on treatment, your CD4 count is probably already increasing.

Your viral load when on treatment is the best measure of how long you can expect treatment to last.

If your viral load goes to below 50 copies/mL then treatment can last for many years. When viral load is this low, resistance usually only develops if you are late or miss taking your medication.

But if it only gets down to a low level, like 500 copies/mL, there is still enough HIV reproducing each day for resistance to develop to the drugs in your combination.

Viral load usually goes down by at least 90% (1 log) after 1 month of treatment, and to below 50 copies/mL after 3-6 months.

How often to use viral load tests – what happens if you do not have access to them

It is not clear how often you need to have your viral load tested. UK and US guidelines recommend a viral load test every 3-6 months when not on treatment, and every 3 months when on treatment. They also recommend a viral load test one month after starting or changing treatment .

If you do not have access to a viral load test, then your doctor will manage you based either on CD4 tests or on clinical symptoms. Not having access to viral load tests should not be used as a reason to not be treated. Many clinics do not have viral load tests in routine use, but still provide treatment effectively.