Why viral load tests are important

Most people only find out that they need to change treatment when their viral load increases.

In at least 50% of cases a low level viral rebound may be a lab error.

In many cases it may be a random ‘blip’.

You need a second test, taken the same day as you get the original result, to investigate further.

If your viral load has continued to rise with the second test, guidelines recommend changing treatment.

This is because, even when viral load is relatively low (between 50—500 copies/mL), HIV can develop resistance. At some point, your viral load will rise much higher and the drugs will stop working completely.

Sometimes viral load remains low but detectable for many months without continuing to climb. This is because the virus is now ‘less fit’. Over time, the virus usually develops new “compensatory” mutations) that make it fit again.

The tests being developed to measure the fitness of a virus are not yet routinely available in the clinic.

Fitness of HIV is discussed in more detail in ‘Using viral fitness’.