Undetectable Viral Load and HIV Transmission Risk

Written by Ann Pietrangelo | Published on July 30, 2013
Medically Reviewed by George Krucik, MD, MBA on July 30, 2013

Even if you have an undetectable viral load test, there is still a risk of transmitting the disease to your partner through sexual activity.

What Is Viral Load?

Viral load is the level of HIV in your blood. Uninfected people have no viral load. If you test positive for HIV, your healthcare team may use viral load testing to monitor your condition.

Your viral load shows how active HIV is in your system. Usually, if your viral load is high, your CD4 count is low. CD4 cells (T-cells) help activate your immune response. Knowing these numbers helps determine treatment. A low or undetectable viral load indicates your immune system is actively working to help keep HIV in check.

Learn the truth behind eight HIV transmission myths »

The Viral Load Test

The first viral load blood test is usually performed soon after diagnosis. Your doctor may order follow-up testing at regular intervals to see how you’re doing. This test is also helpful just prior to and following a change in medication. A growing viral count means your infection is worsening, and new therapies may be required. A downward trend in viral load is a very positive sign.  

What Does “Undetectable” Viral Load Mean?

Antiretroviral therapy (ART) is medication that helps to keep the virus under control. For many patients, HIV treatment can substantially lower viral load levels, sometimes to undetectable levels. That’s a good thing—it means the medication is working.

A word of caution: “undetectable” doesn’t mean it isn’t there or that you no longer have HIV. It simply means that your viral load is so low that the test is unable to measure it.

The Spike Factor

Studies show that there may be temporary spikes, even in people who have had undetectable viral load levels for an extended period. These increased levels may occur between tests, and there may be no outward signs of an increase. Also, although blood and seminal fluid viral load levels are often similar, a person with an undetectable blood viral load can have a higher level of virus in genital fluids.

Viral Load and HIV Transmission

A low viral load means you are less infectious. Studies show it lowers the risk of passing HIV to your sexual partner, and that’s great news. It is important to note, however, that the viral load test only measures the amount of HIV virus that is currently in your blood. An undetectable viral load does not mean HIV isn’t present in your body and in other bodily fluids. HIV is usually transmitted to a sexual partner through seminal fluid or vaginal or anal secretions.

It’s Not Worth the Risk

Even if you have an undetectable viral load test, there is still a risk of transmitting the disease to your partner through sexual activity. It is wise to take precautions to lower that risk even more.

It is never safe to share needles. Continue to use condoms correctly and consistently during sexual activity.

Have an open and honest discussion with your partner, and ask your doctor to explain viral load and the risks of HIV transmission.

Community Viral Load

Aggregating the viral load of HIV-infected people in a specific group is called “community viral load (CVL).” A high CVL may put HIV-negative people within that community at greater risk of contracting HIV.

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.

Good News

The CDC reports that treatment of HIV-positive pregnant women and their babies reduces viral load count and risk of mother-to-infant transmission.

In general, early treatment has been shown to reduce the viral load count in the blood of HIV-infected individuals. Besides lowering the rates of transmission to HIV-negative people, early treatment and lower viral load is helping people with HIV live longer, healthier lives.

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