What is "undetectable"?

Getting to “undetectable” is often the primary goal of treatment for people living with HIV.

What does it mean?

People say HIV viral load is “undetectable” when the levels of virus in the bloodstream are so low that they can’t be measured. When a person takes their HIV medications every day as they’re prescribed, the HIV medications are able to prevent the virus from replicating (or making copies of itself). When this happens, the amount of HIV in a person’s bloodstream goes down to a level so low that viral load tests aren’t able to detect HIV in the person’s blood: so we say the person’s viral load is undetectable.

Why is it important?

Getting to undetectable is important for a few reasons.

Getting your viral load down to undetectable also helps prevent new infections. Studies show that people living with HIV who are on treatment and have a suppressed viral load do not transmit HIV to HIV-negative sex partners. In other words, if you are living with HIV and have an undetectable viral load, you don’t have to worry about passing HIV on to your sex partners. For many people, being undetectable offers a renewed sense of freedom, brings less anxiety around sex, and reduces stigma associated with HIV.

How do I know if I’m undetectable?

Most people living with HIV get to undetectable by taking their HIV medications every day for a period of time (usually one to six months). You will know if you are undetectable from the result of a viral load test, which you can get from your HIV care provider.

Viral load tests with different lower levels of detection may define undetectable differently. Some define undetectable as less than 200 copies/mL while other more recently-developed tests define undetectable as less than 50 copies/mL. When it comes to HIV prevention, large studies show that people with viral loads less than 200 copies/mL are sufficiently virally suppressed to virtually eliminate HIV transmission risk to HIV-negative partners.

Does it mean I’m cured?

No. HIV-negative and undetectable are not the same thing. If you stop taking your HIV-medications (and sometimes for other reasons as well) your viral load will go back up to detectable levels. That’s why it’s important to continue to take your HIV medications every day in the way your provider has instructed. People who are undetectable will still test positive for HIV on HIV tests.

How long will it take for me to get to undetectable?

It’s different for every person. It depends on how high your viral load was before you started treatment, your CD4 cell count, your general health and also what medications you’re taking. Generally, the goal is to get to undetectable after 16 – 24 weeks of treatment.

Have more questions? Read about the research on treatment as prevention—and why we know it work to prevent HIV infections. Also, find out more about why people might not get to undetectable in a Q&A with Dr. Keith Henry.

San Francisco AIDS Foundation supports the Undetectable = Untransmittable message by Prevention Access Campaign. Read more about the initiative.

What is undetectable in U=U?

People living with HIV who are undetectable have a level of HIV in their blood that is so low it can’t be measured by the viral load test. Since different tests have different lower thresholds of detection, some people may wonder what viral loads qualify as undetectable knowing that undetectable equals untransmittable.

Some viral load tests measure viral loads of 400 copies/mL and above. Most modern HIV tests measure levels of virus as low as between 20 – 50 copies/mL. There are special tests used in research studies that can identify as few as between 1 – 5 copies/mL, but these tests are not used in standard HIV care.

There are a few large clinical research studies that help us know how low a viral load should be in order for a person to be undetectable and untransmittable. There is substantial evidence that a viral load less than 200 copies/mL is sufficiently suppressed to be untransmittable.

What’s more important than whether your viral load is 50 copies/mL or 100 copies/mL is how long your virus has been suppressed. Being “durably suppressed” is when your viral load has been undetectable for at least six months after your first undetectable result. The best way to become durably suppressed is to take your HIV medications every day as prescribed. The longer you take HIV medications, the lower your viral load will get in your bloodstream and in other places in your body.

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