HIV 1 Viral Load
Note: this site is for informational purposes only. To view test results or book a test, use the NHS app in England or contact your GP.
The HIV‑1 viral load test measures the amount of HIV‑1 RNA (viral load) in the blood using a blood sample taken from a vein in the arm. It is used to monitor HIV infection, assess disease progression and evaluate how well antiretroviral treatment is working.
Why get tested?
To monitor the status of HIV 1 disease in conjunction with other lab tests and physical disease progression and to guide therapy. Your viral load levels are usually used as an indicator of how well your immune system is dealing with HIV. If you are on anti-HIV treatments, it can be an indicator of how well the treatments are working.
When to get tested?
When first diagnosed with HIV 1, frequently at the start of therapy, and every 3–12 months during lifelong therapy thereafter, or as your doctor recommends. Patients with viral loads consistently <50 copies/mL are likely to be tested less often than patients whose virus level is less well controlled.
Rarely your doctor may also ask for the test;
- If you have had an indeterminate HIV 1/2 antibody/antigen result
- You are at risk and have symptoms of acute HIV, irrespective of the HIV 1/2 antibody/antigen result
Sample required?
A blood sample taken from a vein in your arm.
Test preparation needed?
No test preparation is needed.
What is being tested?
There are two distinct types of HIV but the vast majority of infections circulating in the world are HIV type 1 (HIV 1). This test measures the amount of HIV 1 in your blood. This test detects and/or measures the amount (viral load) of RNA (ribonucleic acid) of the human immunodeficiency virus 1 (HIV 1) in blood. It is the virus that causes acquired immunodeficiency syndrome (AIDS). When a person is infected with HIV 1, the virus replicates – it produces more and more copies of itself and moves into the lymph nodes, spleen, and other parts of the body. In the early stages of infection there may not be any noticeable signs or symptoms of disease or only flu-like symptoms, although the virus is usually present in high amounts. Even when there are no symptoms the virus continues to replicate and to damage or kill immune cells. Eventually, the immune system is so weakened that the disease begins to affect the body’s ability to fight infections and certain cancers. More symptoms begin to appear at this stage as the body becomes more susceptible to infections with microorganisms such as tuberculosis and fungi or other diseases such as Kaposi’s sarcoma.
There is still concern that there is a lot of virus in other places in the body, not just the blood – only 2% of HIV 1 is circulating in the blood, the rest is in the lymph system and other body tissue . Early results indicate that changes in viral load in the blood are mirrored in the lymph system, but research into this is continuing. “Viral load” means the number of HIV particles or copies of the virus present in the blood.
About 3–8 weeks (rarely up to six months) after exposure to the virus, the body begins to produce HIV antibodies in response to the infection. These antibodies can be detected with a screening test to determine if you have been infected with HIV. However, if your exposure occurred within the last few weeks, the level of antibody may not be high enough to be detected. It is in this “window period” of more recent exposure that the virus may be detectable with an HIV 1 RNA test (viral load) to determine your HIV 1 status. Because the level of technology and resources needed to perform this test are high, it is not as widely available as the antibody test and is used infrequently for diagnosis.
As HIV infection progresses the virus continues to replicate and the number of copies of virus, the “viral load”, in the blood increases. If you have been diagnosed with HIV, the measurement of an HIV 1 viral load (HIV 1 RNA) gives your doctor a general indication of how much HIV is present in the body, and how rapidly the virus is replicating. The test can help determine, when to test for drug resistance or if a different type of treatment protocol is needed. Treatment with anti-viral agents can decrease the viral load in the blood to low or undetectable levels, but cannot fully eradicate it from the body. Current guidance recommends that treatment is initiated as soon as a diagnosis of HIV 1 infection is made.
How is the sample collected for testing?
A blood sample is taken by needle from a vein in your arm.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
Common questions
The viral load test is quantitative measurement of HIV 1 nucleic acid (RNA) that provides important information that is used in conjunction with the CD4 cell count:
- to monitor the status of HIV disease,
- to guide recommendations for therapy, and
- to predict the future course of HIV.
Evidence shows that keeping the viral load levels as low as possible for as long as possible decreases the complications of HIV disease and prolongs life.
Initial treatment can take up to 6 months for the viral load to become undetectable, although this is often achieved earlier.
There are several methods for testing viral load; results are not interchangeable so it is very important that the same method be used each time.
A viral load test is requested, usually in conjunction with a CD count, when a patient is first diagnosed with HIV 1. The test result functions as a baseline measurement that shows how actively the virus is reproducing. Your doctor may request a viral load test and a CD4 count about every four weeks to evaluate whether therapy is being effective. To monitor long-term therapy, your doctor will request viral load tests and CD4 counts about every four months.
HIV 1 viral load tests are reported as the number of HIV 1 copies in a milliliter (copies/mL) of plasma (blood without the cells). If the viral load measurement is high, it indicates that HIV is reproducing and that the disease will likely progress faster than if the viral load is low. The clinical trials used to determine the efficacy of HIV antiviral drugs use a cut off of 50 copies/ml as a definition of “undetectable”. The significance of virus levels detectable below this level is still uncertain.
A viral load result that reads “undetectable” does not mean that you are cured. It may mean that either the HIV 1 RNA is not present in your blood at the time of testing or that the level of virus in your blood is below the threshold needed for detection by this test. It is important to note that because of the way the test works there is a natural variation in its results, especially at low levels <1000 copies/mL. So a value of 500 and 700 might appear greatly different but are in fact not significant. Similarly, an undetectable value of <50 copies/mL, which might in fact be 49 copies/mL, and 70 copies/mL have debatable significance. Your clinician may ask to repeat the test if (s)he thinks the result does not fit with your treatment and previous results.
The change in viral load over time is also a very important measurement, however because of the variation in the test the changes need to be significant. Laboratories often report the logarithm (base 10) of the copies/mL in order to help establish the significant difference. A significantly rising level indicates an infection that is getting worse, while a significantly falling level indicates improvement and suppression of the HIV 1 infection. If you are not taking your medication as your doctor has directed, your viral load may not drop as expected, or may even rise if you miss doses your medication.
An uninfected person has no circulating HIV virus in his or her blood and, therefore, a negative or undetectable viral load. There is no “normal” amount of HIV 1 RNA in the blood. A person living with HIV might well have an “undetectable” HIV 1 RNA in the blood, usually because they are on effective treatment.
Normally viral load testing is not be used for diagnosing HIV 1; the HIV 1&2 antibody/antigen test is still the preferred method of choice for this. However, in cases where the antibody/antigen test is indeterminate or where you have been exposed and you are showing signs that you may be acutely infected, your clinician may request a viral load.
There is no direct link between viral load levels and exercise, nutrition, or other lifestyle factors. However, general health advice (such as stopping smoking, taking regular exercise, eating a balanced diet) is also relevant to people with HIV and will help you stay strong.