What does Undetectable = Untransmittable mean?​

"Undetectable" means that a test cannot detect the amount of virus in a blood sample from a person living with HIV. Someone who is "undetectable" for 6 or more continuous months while on treatment does not transmit the virus.

An undetectable viral load has different measures depending on the test and country. For instance, in the U.S., this means about <40 copies of HIV per milliliter of blood. Studies show that HIV transmission does not occur if viral load is <200 copies/ml. This is also called being “virally suppressed.” Being “undetectable” and “virally suppressed” are often used interchangeably. They both indicate that transmission will not occur.

Undetectable doesn't mean that there's no HIV present in blood. It just means the virus is being controlled. If a person with undetectable HIV stops their medications, the virus will return to being detectable which increases the risk of transmission.

The lingo

These terms are often used when describing this evidence-based HIV prevention method: "undetectable", "TasP" (or "treatment as prevention"), and "U=U" or "undetectable equals untransmittable". Basically, they all mean the same thing ... if a person living with HIV stays undetectable for 6 months or more then they cannot transmit HIV through sex.

Scientific evidence

Three international studies showed no HIV transmissions among mixed-status couples when the partner with HIV was undetectable for 6 months or longer. This included more than 75,000 acts of reported condomless sex among mixed-status heterosexual and gay male couples. The studies were HPTN 052PARTNER and Opposites Attract. To date worldwide there are no verified reports of someone getting HIV from a partner who is undetectable.

Other ways to prevent HIV infection (for HIV-negative partners in mixed-status couples)

External Condoms:

External condoms are worn over the penis to help protect against HIV and STIs (sexually transmitted infections). They are easy to use and may be available for free at local community clinics and health care/community-based organizations, or for sale at many drugstores.


Learn how to use an external condom HERE.

Internal Condoms:

Internal condoms are worn inside vagina/frontal area or anus/back area and are another way to also help prevent HIV infection and exposure to STIs. Although not as commonly used as external condoms, they may also be offered for free by local community clinics and health care/community-based organization, or for sale by prescription at some pharmacies.


Learn how to use an internal condom HERE.

PrEP (pre-exposure prophylaxis):

PrEP is a daily pill that, when taken as prescribed, can provide high levels of protection to help prevent HIV infection. PrEP can be taken by all sexes, all genders.
Ask your doctor about PrEP. They may be able to provide PrEP services or refer you to someone who can. Don’t have a provider? We can help you find a local PrEP-friendly provider. Chat with us by clicking the chat bubble on the right.


To learn more about PrEP, click HERE.

PEP (post-exposure prophylaxis):

PEP is a 28-day pill prescription that can be taken by people who are not on PrEP and who may have been exposed to HIV in the past 72 hours. When taken as prescribed, PEP can help prevent HIV infection.
Call your doctor if you think you need PEP, or go to your local ER or urgent care facility to get it. You can also chat with us to help find a local PEP provider by clicking the chat bubble on the right.


To learn more about PEP, click HERE.

I want more information!

For more information on the U=U campaign and the science behind U=U, visit Prevention Access Campaign

For more information for trans and cis women living with HIV, visit the resources on HIVE's Women Living with HIV and Trans Women pages . 

For more information for cis and trans men living with HIV, visit the resources on HIVE's Men Living with HIV and Trans Men pages. 

Visit our U=U for advocates page for more in-depth resources and information. 

In collaboration with Prevention Access Campaign logo