HIV - Undetectable viral load: undetectable = untransmittable," or "U=U."

 

Advances in medicine have made it possible for a person living with HIV to have an undetectable viral load with traditional blood testing methods. If HIV is undetectable over an extended period, it is also transmittable.

An undetectable viral load is when a person has so little of the virus in their blood that a test cannot identify it.
While an undetectable viral load does not mean that a person's HIV is cured, it does offer tremendous promise for a person's overall health and for reducing viral transmission.
Typically, the higher a person's viral load, the greater their chance of transmitting HIV if they have condom-less sex or share needles.
However, taking antiviral therapy can reduce the amount of viral copies in a person's blood to levels that are so low that they do not register on a viral load blood test.
Healthcare providers call this an undetectable viral load. While the measurement for an undetectable viral load can vary by laboratory, it is usually fewer than 40 copies per milliliter (mL).
A healthcare provider may also use other terms related to an undetectable viral load, such as:

• Durably undetectable: When a person's viral load has been at undetectable levels for 6 months or more, it is durably undetectable.
• Viral load suppression: This term means that a person's viral load is fewer than 200 copies/ml. While the virus is not undetectable, people with a viral load this low will not transmit the virus.

An undetectable viral load is an important milestone for a person living with HIV because it signifies that the amount of the virus in the body is not likely to cause any health problems.

Undetectable equals transmittable

Several long-term landmark studies into the effects of antiretroviral therapy on HIV have led researchers to conclude that undetectable levels of HIV mean that the virus is untransmittable.
In a 2016 study, researchers enrolled 1,166 couples who had vaginal or anal sex without a condom. In each couple, one partner had HIV, was virally suppressed, and was taking antiretroviral therapy.
The researchers studied them for an average of 1.3 years per couple.
In the follow-up period, there were no instances of HIV transmission within the couples. This means the member of the couple who had HIV did not transmit the virus to the person without HIV while they were virally suppressed.
A study presented at the 2017 International AIDS Society conference came to similar conclusions.
The study's authors recruited 358 same-sex male couples in Australia, Thailand, and Brazil.
In each couple, one partner was virally suppressed, taking antiretroviral therapy, and had HIV. At the study's conclusion, the authors found no evidence of HIV transmission between partners after sex without a condom.
Results from these and other studies have led many large organizations, including the Centers for Disease Control and Prevention (CDC) and the United Nations, to concur that undetectable viral levels mean that HIV is untransmittable.
They may refer to the conclusions as "undetectable = untransmittable," or "U=U."