• Also Known As:
  • HIV Nucleic Acid Amplification Test (NAAT or NAT)
  • HIV by PCR
  • HIV RNA Test
  • Plasma Viral Load (PVL) Test
  • Formal Name:
  • Human Immunodeficiency Virus RNA
  • quantitative
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Human immunodeficiency virus (HIV) is the virus that causes HIV infection. In the United States, HIV is most often spread through anal sex, vaginal sex, and sharing injectable drug equipment like needles. The most advanced stage of an HIV infection is called acquired immunodeficiency syndrome (AIDS).

An HIV viral load test is a type of HIV test that measures the amount of HIV genetic material in the blood. Testing a patient’s viral load can be used to diagnose an HIV infection, guide care, and monitor a patient’s response to treatment.

About the Test

Purpose of the test

The purpose of testing for HIV viral load is to measure the amount of viral RNA which is the genetic material of the virus in a small sample of a patient’s blood. This test may be used to diagnose HIV as well as plan and monitor HIV treatment.

Diagnosing HIV

HIV viral load testing is one test that can determine if a person has an HIV infection. There are three types of diagnostic HIV tests: nucleic acid amplification tests (NAATs), antigen/antibody tests, and antibody tests. The HIV viral load test is a type of NAAT test.

Although NAAT testing can determine if a person has been infected within 10 to 33 days after an exposure, it is not routinely used to screen patients without symptoms or exposure to the virus. An HIV viral load test may be ordered to diagnose patients only after a high-risk exposure or when patients are experiencing early symptoms of HIV. This test may also be used to diagnose HIV in infants.

Guiding HIV Treatment

Antiretroviral treatment (ART) is treatment for HIV used to suppress the virus and to prevent HIV from advancing to AIDS. HIV viral load testing is used to guide treatment for patients with HIV by providing information about when to begin ART, which regimen of ART medications may be appropriate, and when to change to a new ART regimen.

Monitoring HIV

HIV viral load testing is used to understand a patient’s response to ART. One goal of ART is to suppress the virus until the patient’s viral load is undetectable, which means it is too low to be detected on an HIV viral load test.

Once a patient begins ART, it usually takes 3 to 6 months for the viral load to reach an undetectable level. When used to monitor treatment, viral load testing is used alongside a CD4 count test, which measures the amount of one type of white blood cell that is destroyed by HIV. Together, these two tests provide information about how well a patient’s treatment is controlling their HIV infection.

What does the test measure?

An HIV viral load test measures the genetic material of the HIV virus, also called RNA. A patient’s HIV viral load describes how many copies of HIV RNA are present in the blood.

When a person is initially infected with HIV, the virus begins to replicate and produce more and more copies of itself. CD4 cells are a type of white blood cell that are the main target of HIV. The virus invades CD4 cells and uses them to replicate.

In the early stages of HIV infection, the virus is often present in high amounts even though there may be few, if any, noticeable symptoms. Without treatment, the virus continues to replicate and the viral load increases as the amount of CD4 cells decreases.

Several weeks after infection, the immune system begins to produce HIV antibodies meant to defend against the virus. HIV antibodies temporarily suppress the HIV viral load. Although a person’s initial symptoms may resolve after the production of HIV antibodies, the infection does not go away.

Unless an HIV infection is detected and treated, it may continue to destroy CD4 cells and slowly degrade a person’s immune system. Over time, the immune system can become so weakened that the disease begins to affect the body’s ability to fight infections and certain types of cancer.

When should I get an HIV viral load test?

Diagnostic testing for HIV viral load may be used in patients with a possible or known exposure to the virus who are suspected of having an acute HIV infection. An acute HIV infection describes the earliest stage of HIV infection when some people begin to develop signs and symptoms of this disease. Although up to 60% of people infected will not have symptoms during this period, when they do occur symptoms of an acute HIV infection may include:

  • Fever
  • Swollen lymph nodes
  • Sore throat
  • Rash
  • Muscle or joint pain
  • Diarrhea
  • Headache

HIV viral load testing is used in infants born to a person infected with HIV. When and how often infants are tested depends on risk of infection. Infants born to a parent who was effectively treated with ART and maintained an undetectable viral load during pregnancy are considered low risk. Infants born to a parent whose HIV infection wasn’t sufficiently suppressed are considered high risk.

Low-risk infants may be tested for HIV at 2 to 3 weeks of age, then again at 4 to 8 weeks, and finally at 4 to 6 months of age. In high-risk infants, HIV viral load testing may also be performed at birth and at 8 to 10 weeks of age.

When used to guide treatment and monitor HIV, an HIV viral load test is typically ordered when a patient is first diagnosed. After this baseline testing, an HIV viral load test is ordered again when a patient begins ART and at regular intervals thereafter. Several factors can affect this timeline, including a patient’s ability to follow recommended treatment. Generally, HIV viral load testing occurs at the following intervals:

  • After an initial diagnosis
  • When starting ART
  • Within 2 to 4 weeks after starting ART
  • Every 4 to 8 weeks until the viral load is suppressed and undetectable
  • Once the virus is undetectable, every 3 to 4 months during the first two years of ART
  • Every 6 months in some patients who have undetectable viral loads for two years or longer

If a patient changes their ART regimen due to side effects or because their viral load is suppressed, an HIV viral load test may be ordered after 4 to 8 weeks to confirm the effectiveness of the new treatment regimen.

After a patient’s viral load is undetectable on ART, patients may have occasional “blips” in which the viral load becomes detectable again for a short time. Although an isolated “blip” is not a sign that treatment is no longer working, some patients experience more significant increases in viral load that do indicate the HIV infection may have become resistant to ART or that treatment has failed. In patients with a drug-resistant virus, HIV viral load testing may be ordered 4 weeks after beginning a new ART regimen, then at 4 to 8 week intervals until the viral load becomes undetectable.

Finding an HIV Viral Load Test

How to get tested

HIV viral load testing is ordered by a physician or other health professional. Testing can be performed at a hospital, doctor’s office, or other medical setting.

Can I take the test at home?

HIV viral load testing requires a blood sample drawn by a health professional and is not available as an at-home test.

At-home HIV testing is available to screen undiagnosed patients for HIV, with both rapid and self-collection kits available.

How much does the test cost?

The cost of HIV viral load testing depends on where a patient has the test conducted and whether they have health insurance. Additionally, laboratory and other charges vary. Patients should discuss the costs of testing with their doctor, the laboratory, and/or their health insurance provider.

If paying for HIV testing and treatment is a concern, resources are available to help people with HIV gain access to medical care through the US Department of Health and Human Services: How to Find HIV Treatment Services.

Taking an HIV Viral Load Test

An HIV viral load test requires a sample of blood. Usually, blood is drawn from a vein on the inside of a patient’s elbow or on the back of the hand.

Before the test

No preparation is required before having an HIV viral load test. Some health conditions and vaccinations may cause a temporary change in a patient’s HIV viral load, so patients should tell their doctor about recent illness, outbreak of herpes simplex, or vaccinations.

During the test

During an HIV viral load test, several steps are taken to draw a sample of a patient’s blood:

  1. A puncture site on the patient’s arm is located and cleaned to kill germs on the skin.
  2. The health care professional ties an elastic band around the upper arm to increase pressure and cause the veins to swell.
  3. Once the puncture site is prepared, a needle is gently inserted into the vein.
  4. Blood is drawn from the vein through the needle and into a vial or tube.
  5. Once sufficient blood is collected, the elastic band is removed from the upper arm.
  6. The needle is removed and pressure is applied to the puncture site to reduce bruising and bleeding.

A blood draw is a relatively quick process, often taking less than three minutes. Patients may experience a brief prick or sting of pain when the needle is inserted and withdrawn.

After the test

Once the blood draw is finished, patients can remove the pressure placed in the puncture site after a minute or two. Bandages or gauze may also be used to prevent bleeding, which can be kept on for a few hours.

No additional restrictions on activities are required after a blood draw for an HIV viral load test.

HIV Viral Load Test Results

Receiving test results

The results of HIV viral load testing may be available after several days. Results may be sent directly to the patient and their doctor. Results may also be discussed during a follow-up visit, over the phone, or through an online health portal.

Patients may find it helpful to ask their health care provider for additional information about how and when they will receive test results.

Interpreting test results

HIV viral load tests are reported as the number of HIV copies in a milliliter (copies/mL) of blood.

A high HIV viral load generally indicates that HIV is present and replicating. The higher a person’s viral load, the higher their risk of developing health conditions associated with AIDS. In an untreated early HIV infection, a patient’s HIV viral load may be over 100,000 copies/mL. In patients on antiretroviral treatment (ART), sustained HIV viral loads of 200 copies/mL or higher are associated with potential treatment failure. This may mean that the current ART regimen is no longer effective and needs to be changed.

Low HIV viral loads that are consistently less than 200 copies/mL indicate that the virus is adequately suppressed and that the risk of disease progression is low.

An undetectable viral load means that the level of HIV RNA in the blood is below the threshold needed for detection by an HIV viral load test. The amount of the HIV viral load that is considered undetectable varies by the type of laboratory test method used, ranging from less than 20 to 75 copies/mL. An undetectable viral load does not mean that HIV is cured, but a patient who is HIV-positive and has an undetectable viral load by taking ART has almost no risk of transmission to an HIV-negative partner through sex.

While the results of a single HIV viral load test are important in diagnosing HIV, guiding treatment, and patient monitoring, changes in a patient’s viral load over time may provide more information than a single test result.

Are test results accurate?

HIV viral load testing is a vital tool for monitoring the state of a patient’s HIV infection. To ensure accuracy in monitoring changes in a patient’s viral load over time, patients may be encouraged to have the same type of test conducted each time and, preferably, at the same laboratory.

There are several methods that may be used by laboratories to measure a patient’s HIV viral load. To ensure that test results can be compared and interpreted consistently over time, it’s best for patients to have the same type of viral load test each time. This helps to provide an accurate picture of whether the virus is replicating or stable with the current ART regimen.

A patient’s doctor can discuss how to ensure that the viral load testing method is consistent across multiple tests.

Do I need follow-up tests?

After a patient is diagnosed with HIV using an HIV viral load or other test, the doctor may order other tests, such as a CD4 count, HIV genotype test, and tests that provide information about organ function and other potential infections.

In patients who are receiving antiretroviral treatment (ART), a high viral load can indicate that treatment is not effective. In this situation, the doctor may recommend drug-resistance testing to determine if a patient’s virus has become resistant to the current regiment and to decide which ART medications will be effective against an individual’s HIV infection.

A low or undetectable viral load during treatment for HIV means that a patient’s current treatment is effective. Follow-up testing after these results involves regular HIV viral load and other tests at regular intervals determined by a patient’s health and previous test results.

Questions for your doctor about test results

It may be helpful to gather questions for the doctor about a patient’s HIV viral load results. Questions to learn more about test results may include:

  • What is my HIV viral load?
  • How does this test result compare to previous results?
  • Do I need any treatment or a change in treatment based on my results?
  • How can I talk to my sexual partners about HIV?
  • When should I be tested for STDs and how often?

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