The viral load is the level of HIV in the blood. HIV-negative people have no viral load. If a person tests positive for HIV, their healthcare team may use viral load testing to monitor their condition.

The viral load shows how active HIV is in the system. Usually, if the viral load is high for a long time, the CD4 count is low. CD4 cells (a subset of T cells) help activate the immune response. HIV attacks and destroys CD4 cells, which reduces the body’s response to the virus.

A low or undetectable viral load indicates the immune system is actively working to help keep HIV in check. Knowing these numbers helps determine a person’s treatment.

The first viral load blood test is usually performed soon after a diagnosis of HIV.

This test is helpful before and after a change in medication. A healthcare provider will order follow-up testing at regular intervals to see whether the viral load changes over time.

A growing viral count means a person’s HIV is worsening, and changes to current therapies may be needed. A downward trend in viral load is a good sign.

Antiretroviral therapy is medication that helps to keep the viral load in the body under control. For many people, HIV treatment can substantially lower viral load levels, sometimes to undetectable levels.

A viral load is considered undetectable if a test can’t quantify the HIV particles in 1 milliliter of the blood. If a viral load is considered undetectable, it means the medication is working.

According to the Centers for Disease Control and Prevention (CDC), a person with an undetectable viral load has “effectively no risk” of sexually transmitting HIV. In 2016, the Prevention Access Campaign launched the U=U, or Undetectable = Untransmittable, campaign.

A word of caution: “undetectable” doesn’t mean the virus particles aren’t there, or that a person no longer has HIV. It simply means that the viral load is so low that the test is unable to measure it.

HIV-positive people should consider continuing on antiretroviral medications to remain healthy and keep their viral loads undetectable.

Studies show that there may be temporary viral load spikes, sometimes called “blips.” These spikes can happen even in people who’ve had undetectable viral load levels for an extended period.

These increased viral loads may occur between tests, and there may be no symptoms.

Viral load levels in blood or genital fluids or secretions are often similar.

A low viral load means a person is less likely to transmit HIV. But it’s important to note that the viral load test only measures the amount of HIV that’s in the blood. An undetectable viral load doesn’t mean HIV isn’t present in the body.

HIV-positive people may want to consider precautions to lower the risk of HIV transmission and to reduce the transmission of other sexually transmitted infections (STIs).

Using condoms correctly and consistently when having sex is an effective STI prevention method. Check out this guide to using condoms.

It’s also possible to transmit HIV to partners by sharing needles. It’s never safe to share needles.

HIV-positive people may also want to consider having an open and honest discussion with their partner. They can ask their healthcare providers to explain viral load and the risks of HIV transmission.

Q:

Some sources say that the chances of transmitting HIV with an undetectable viral load is zero. Is this true?

A:

Based on the findings of three separate high-quality studies, the CDC now reports that the risk of HIV transmission from someone who is on “durable” antiretroviral therapy (ART) with viral suppression is 0 percent. The studies used to make this conclusion noted that transmission events, when they occurred, were due to acquisition of new infection from a separate, non-suppressed partner. Because of this, there is virtually no chance of transmitting HIV with an undetectable viral load. Undetectable was defined differently in the three studies, but all were < 200 copies of virus per milliliter blood.Daniel Murrell, MDAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.

Taking antiretroviral medications during pregnancy and delivery can greatly reduce the risk of passing HIV on to a child. Having an undetectable viral load is the goal during pregnancy.

Women can take HIV medications safely during pregnancy, but they should talk to a healthcare provider about specific regimens.

If an HIV-positive woman is already taking antiretroviral medications, pregnancy may affect how the body processes her medication. Certain changes in treatment might be needed.

The amount of the viral load of HIV-positive people in a specific group is called community viral load (CVL). A high CVL may put people within that community who don’t have HIV at greater risk of contracting it.

CVL can be a valuable tool in determining which HIV treatments effectively lower viral load. CVL may be useful in learning how lower viral load may affect transmission rates within specific communities or groups of people.

Having an undetectable viral load greatly lowers the chances of transmitting HIV to sexual partners or through the use of shared needles.

Additionally, the CDC reports that treatment of pregnant women with HIV and their babies reduces viral load count as well as the risk of the baby contracting HIV in utero.

In general, early treatment has been shown to reduce the viral load count in the blood of people with HIV. Besides lowering the rates of transmission to people who don’t have HIV, early treatment and lower viral load is helping people with HIV live longer, healthier lives.

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