When a person has very little virus, they are said to have an undetectable viral load. Viral load is measured in units called copies. The standard blood tests used in UK clinics can measure viral load down to 20 or 50 copies per millilitre of blood. Anything less than this is called undetectable.

Is 20 viral load undetectable?

More recently-developed tests can measure levels of virus as low as between 20 – 50. With these tests, only people with viral loads <50 (and sometimes <20) are considered to be undetectable.

What happens if your viral load is low?

A low viral load means that your ART is working well and controlling your HIV. If you have an undetectable viral load, it means that the amount of HIV in your body is so low that you cant pass it on to other people through sex.