Undetectable HIV means a person with HIV has a viral load that is so low the virus cannot be passed on. This is known as an undetectable=untransmittable status (U=U) and is achieved by
antiretroviral therapy (ART).
Doctors define viral load as the number of HIV copies in a milliliter of blood (copies/ml). In essence, it refers to the amount of HIV in a person’s blood.
The main goal of ART is to reach and maintain viral suppression. This happens when a person living with HIV has a very low viral load or fewer than 200 copies of HIV per milliliters of blood (<200 copies/mL).
There is no cure for HIV, but viral suppression reduces a person’s risk of passing HIV onto someone else while also lowering their chances of developing HIV complications.
ART can even reduce someone’s viral load to undetectable levels, which makes HIV untransmittable.
U=U stands for undetectable equals untransmittable.
An HIV-positive person’s viral load is undetectable when they have so little virus in their blood that a standard lab test cannot detect it. When someone’s viral load is undetectable, they cannot pass HIV to someone else through sex. This is supported by “an overwhelming body of clinical evidence,” according to the National Institute of Allergy and Infectious Diseases.
Studies of condomless sex between HIV-positive and HIV-negative partners have found zero cases of transmission within
Having an undetectable viral load also helps prevent HIV transmission from parent to child through pregnancy, labor, delivery, or breastfeeding or chestfeeding. However, there is still a small risk of HIV transmission through breastfeeding or chestfeeding.
More research is necessary to learn how an undetectable viral load affects the risk of HIV transmission through sharing needles, syringes, or other drug equipment. It likely reduces the risk, but experts do not know how much. If someone uses injected drugs, they should never share needles, syringes, or other drug injection equipment with other people.
Having an undetectable viral load is not the same as being HIV-negative.
People who are HIV-negative have never contracted HIV.
People with an undetectable viral load are HIV-positive, but the amount of virus in their blood is so small that a standard lab test cannot detect it. A very small amount of HIV remains in their blood and could multiply to detectable and transmittable levels if they do not follow their prescribed treatment or their treatment stops working.
When someone receives an HIV diagnosis, it is important to get early and continuous treatment with ART to reach and maintain an undetectable viral load. A doctor will also recommend viral load testing to monitor the level of HIV in their blood. This can help them learn how their treatment is working and whether changes to their treatment are necessary.
For someone to reach an undetectable and untransmittable viral load, it is important for people living with HIV to follow their doctor’s instructions for early and continuous treatment with ART. It is also important to start treatment right away, even if they have not developed any symptoms of HIV.
ART typically involves a combination of two to three HIV medications, which may include drugs from the following classes:
- nucleoside reverse transcriptase inhibitors (NRTIs)
- non-nucleoside reverse transcriptase inhibitors (NNRTIs)
- protease inhibitors (PIs)
- integrase strand transfer inhibitors (INSTIs)
- fusion inhibitors
- CCR5 antagonists
- post-attachment inhibitors
The specific combination of medications that a doctor prescribes will depend on the person’s individual needs. If one combination of medications does not suppress their viral load or it causes side effects that are difficult to manage, their doctor may recommend a change in treatment. Sometimes, a combination of medications that works well at first may become less effective over time.
Most ART medications are available as pills that a person takes once or twice a day. They may need to take multiple pills or a single pill that contains multiple drugs.
It is important for people who are HIV positive to take their medication exactly as their doctor prescribes, even after they reach an undetectable viral load. If they skip a dose or stop taking their medication, their viral load can increase and may become detectable again. They need to keep taking their medication to keep their viral load undetectable.
A person should inform a doctor if they have any concerns about their prescribed treatment. The doctor can explain their treatment options, including the potential benefits and risks of changing treatment.
According to the U.S. Department of Health and Human Services (HHS), most HIV-positive people who take ART as a doctor prescribes reach an undetectable viral load within 6 months.
In some cases, it may take less or more time to reach an undetectable viral load.
It can take several months of HIV treatment for a person’s viral load to become undetectable.
It is also possible for an undetectable viral load to become detectable again, especially if someone does not take their HIV treatment exactly as prescribed or develops drug resistance to their treatment.
If a person living with HIV has a detectable viral load, they can pass the virus onto an HIV-negative sexual partner.
Always using a condom during vaginal, anal, or oral sex reduces the risk that an HIV-positive person will transmit the virus to an HIV-negative partner. If the condom breaks, the HIV-negative partner should contact a doctor to ask about postexposure prophylaxis (PEP). This is a medication that a person can take within 3 days of HIV exposure to lower their risk of contracting the virus.
The HIV-negative sexual partner can also lower their risk of contracting the virus by taking pre-exposure prophylaxis (PrEP). This is a medication that a person can take on a regular basis to lower their risk of contracting HIV. Taking PrEP as prescribed can lower their risk of contracting HIV from sex by about 99%.
A person living with HIV might be reluctant to tell potential sexual partners about their HIV status, perhaps due to fear of stigma or discrimination.
But talking with potential partners about their HIV status allows people to make informed decisions about their sexual activities. An HIV-positive person can inform a potential partner if their viral load is undetectable and how that prevents HIV transmission through sex. They can also discuss other strategies to reduce the risk of transmission, such as using condoms and PrEP.
In some jurisdictions, telling potential partners about their HIV status may also help protect HIV-positive people from legal risks.
It is also important for people living with HIV to inform potential partners if they have any sexually transmitted infections (STIs). They can talk with a doctor to learn how often they should get tested for STIs. If they test positive for another STI, it is important to get treatment and take steps to prevent transmission.
HIV-positive people can also protect themselves by asking potential sexual partners about their STI status. If a potential partner has an STI or has not received recent STI testing, using condoms during sex lowers the risk of transmission.
Below are some commonly asked questions about undetectable HIV.
How long can HIV be undetectable?
A person undergoing daily antiretroviral therapy (ART) can effectively keep their viral load at an undetectable level.
Nevertheless, even while undergoing treatment, there may be intermittent, minor upticks in viral load that subsequently return to an undetectable state, commonly referred to as “
Should treatment be discontinued entirely, HIV levels will begin to accumulate, eventually becoming detectable once more.
How can you tell if someone is HIV undetectable?
When a person’s viral load is too low to be measure by a blood test, they have undetectable HIV. A health care professional will perform blood tests and let a person know when this is the case.
Current treatments for HIV can lower the amount of virus in a person’s blood to undetectable levels.
When a person living with HIV has an undetectable viral load, they cannot transmit the virus to others through sex. It also lowers the risk of transmission from parent to child through pregnancy, labor, delivery, and breastfeeding or chestfeeding.
Although more research is necessary, it may also reduce the risk of transmission through sharing drug injection equipment.
Early and continuous HIV treatment is essential for reaching and maintaining an undetectable viral load. In addition to reducing the risk of transmission, this also lowers the risk of HIV complications.
A person can talk with a doctor to learn more about their viral load test results, treatment options, and strategies for reducing the risk of HIV transmission and complications.