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Women and HIV Viral Load

July 27, 2015

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Table of Contents


What Is a Viral Load?

HIV attacks immune system cells called CD4 cells. HIV enters these cells and turns them into virus factories that produce thousands of copies of HIV. As the virus grows, it damages or kills CD4 cells, weakening your immune system.

Viral load is the amount of HIV (number of viruses or copies) in your bloodstream. The higher the amount of HIV, the more your immune system becomes damaged.

Viral load can be measured by several different lab tests: a polymerase chain reaction (PCR) test, a branched DNA (bDNA) test, or a nucleic acid sequence-based assay (NASBA). All these tests are accurate, but each has a different way to measure the amount of virus. It is best to stick with the same kind of test and not switch among them, or it will be difficult to compare results over time.

Viral load results are reported as the number of copies of HIV in one milliliter (ml) of blood. The lower the number, the less virus there is in your blood. Numbers can range from several million copies to as few as 20 copies. If you have fewer than 50 or 20 copies, your health care provider may tell you that your results are "undetectable."

Being undetectable is a great result because it means your virus is under control. However, undetectable does not mean that you have been cured of HIV or that you cannot pass it to others. It just means that there is not enough HIV in your bloodstream for the test to measure. It is also important to know that labs that test viral load have different cut-offs below which they cannot detect HIV. For example: you could have 35 copies of HIV in your blood, and in lab #1, which cannot detect any HIV below 50 copies, your viral load would be considered 'undetectable.' However, in lab #2, which cannot detect any HIV below 20 copies, your viral load would be considered detectable.

How Are Viral Load Results Used?

Viral load tests are an important tool to:

  • Check HIV progression
    While CD4 cell counts measure how healthy your immune system is today, viral load tests can help figure out whether you are at risk for more immune damage in the near future. A viral load test tells you how active HIV is in your body. When compared over time, viral load results show if the amount of HIV in your bloodstream is higher or lower than it was before. The higher your viral load, the more actively HIV is reproducing and the more likely you are to lose CD4 cells in the future.
  • Measure how well HIV drugs are working
    HIV drugs prevent the virus from making copies of itself (reproducing). When a combination of HIV drugs (your drug regimen) is working, the viral load usually goes down within weeks of starting the drugs. If your viral load goes up while taking HIV drugs, your drugs may not be working as well as they should. It is important to talk to your health care provider about the best next step, and to tell her or him if you are having any problems taking your HIV drugs on schedule. If you do not take your drugs correctly, it can cause problems that may increase your viral load. Your health care provider may ask to re-test your viral load at that time or after another few weeks. Your provider may also suggest that you change some or all of your drugs.

One goal of HIV treatment is to keep viral load levels as low as possible for as long as possible. This gives you the best chance of staying healthy. With effective HIV treatment regimens, viral load can be reduced to undetectable in many people. This is a great result. It means that your HIV drugs are working and you are doing a great job taking them. However, HIV is still in your body. If you stop taking your HIV drugs, the virus usually starts reproducing and your viral load will increase.

While a lower viral load generally means you are less likely to pass HIV to others, it is important to know that even with an undetectable viral load you might infect someone else with HIV if you share needles or have unprotected sex. Researchers recently found that, in heterosexual ('straight') serodiscordant couples (one person is living with HIV and the other person is HIV-negative), having an undetectable viral load greatly reduces the chance of spreading HIV to the uninfected partner. By combining the results of several studies, researchers calculated that, in 1,000 serodiscordant couples who had sex for one year, if the partner living with HIV was taking HIV drugs and had an undetectable load, then only one or two HIV-negative partners would become infected with HIV.

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This article was provided by The Well Project. Visit The Well Project's Web site to learn more about their resources and initiatives for women living with HIV. The Well Project shares its content with to ensure all people have access to the highest quality treatment information available. The Well Project receives no advertising revenue from or the advertisers on this site. No advertiser on this site has any editorial input into The Well Project's content.


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