HIV viral load
Viral load is an important blood test carried out to check how well HIV is being managed.
The HIV viral load is the number of copies of the human immunodeficiency virus in your blood and other parts of your body. The HIV viral load test involves taking a blood sample from a vein in your arm. The amount of HIV in your blood is then measured.
Keeping your viral load low can reduce complications from HIV disease and extend your life.
When to have a viral load test
The different times you need a viral load test include:
- Immediately after diagnosis. This gives what's called a baseline measurement. Future results can be measured against it.
- Every two to eight weeks at the start of treatment or with a change in treatment. This helps to evaluate how well medication is working.
- Every three to six months or as your doctor directs if treatment is effective.
Do not have the HIV viral load test within four weeks of any infection or immunisation, as these can cause fluctuations with your test results.
How HIV viral load is measured
There are several different methods for measuring your HIV viral load. It is best to stay with the same method each time because different tests can produce slightly different results. New, more sensitive methods are constantly being developed. These are the three common tests currently used to detect HIV viral load. All work well.
PCR (polymerase chain reaction) uses an enzyme to multiply the HIV RNA in the blood sample. (RNA is the part of HIV that knows how to make copies of HIV.) This makes it easier to measure the amount of HIV RNA in the blood sample. A newer ultra-sensitive PCR test can measure down to 50 copies of HIV RNA.
bDNA (branched-chain DNA) creates a light signal whose brightness depends on the amount of viral RNA present.
NASBA (nucleic acid sequence-based amplification) amplifies the viral proteins, making HIV viral load easier to measure.
What HIV viral load test results mean
The HIV viral load test measures the number of HIV copies in a millilitre of blood.
- If your HIV viral load is high, HIV is reproducing and the disease may progress more quickly. For someone not on treatment a high HIV viral load is over 100,000 copies. It can be as high as 1 million or more.
- If your HIV viral load is low, HIV may not be actively reproducing and the disease may progress more slowly. For someone not on treatment a low viral load is below 10,000 copies.
- If your HIV viral load can't be detected, this does not mean you are cured. The level of HIV virus may be so low that the test can't pick it up. A more sensitive test may be able to detect it. It's important to also know that the HIV viral load test does not measure HIV in other parts of the body, where HIV may be present. Only about 2% of HIV is in the blood.
Even if your HIV viral load is undetectable, there is still a small chance of infecting others.