HIV Undetectable = Untransmittable (U=U) Fact Sheet

Medicines to treat HIV can eliminate the risk of sexual transmission. In August 2016, the New York City (NYC) Health Department agreed with other public health and medical organizations that people with HIV who maintain an undetectable viral load for at least six months do not transmit HIV through sex. In September 2017, the Centers for Disease Control and Prevention and the New York State Department of Health (PDF) agreed with this finding, which is known as "Undetectable = Untransmittable," or "U = U".

How Does HIV Treatment Prevent HIV Transmission?

Antiretroviral medicines are very effective at controlling HIV. They do not cure HIV infection or remove the virus from the body, but if taken every day, as prescribed, HIV medicines stop the virus from multiplying. This prevents the virus from damaging the immune system and stops sexual transmission to others.

What Does "Undetectable" Mean?

"Undetectable" means that the level of HIV in a person's blood is so low that it doesn't show up on a viral load test. If a person is undetectable, HIV can still be hiding in their body, but the amount is so low that HIV cannot be passed to others through sex.

How Do We Know That "Undetectable = Untransmittable"?

Three recent studies -- HPTN 052, PARTNER and Opposites Attract -- followed male couples and heterosexual couples in which one partner was HIV-positive and the other HIV-negative. During these studies, not one HIV-positive person who was taking antiretroviral medicines and was virally suppressed passed HIV to their negative partner. In the PARTNER and Opposites Attract studies, male couples had anal sex without condoms more than 34,000 times and heterosexual couples had vaginal or anal sex without condoms more than 36,000 times without a virally suppressed partner ever passing HIV to the negative partner. This is strong evidence that people do not sexually transmit HIV if they have an undetectable viral load.

Related: Celebrate U=U! What Undetectable = Untransmittable Means for the HIV Community

How Do I Get My Viral Load to Be Undetectable?

If you have HIV, take antiretroviral medicines as prescribed by your health care provider. After you start your medicine, your provider will take blood samples to determine when the level of HIV virus in your blood has become undetectable. Once you have been undetectable for six months, you will not be able to sexually transmit HIV as long as you take your antiretroviral medicines and keep your viral load undetectable.

Programs in NYC can help patients start or stay in HIV care and take their medicines every day. These include the Undetectables, the Positive Life Workshop and, for those eligible for Ryan White services, the NYC Ryan White Care Coordination Programs.

If I Am HIV-Negative, Should I Avoid Having Sex With People Who Have HIV?

Having sex with someone who knows they have HIV but is on treatment and has an undetectable viral load is much safer than having sex with someone who has HIV and does not know it, or someone who knows they have HIV but is not on treatment.

A person who was recently infected with HIV can have a very high viral load and can easily pass HIV to their partners.

A person with HIV who has kept their viral load undetectable for six months will not pass HIV to their sexual partners, even if they have sex without condoms.

If My Partner Tells Me They Have an Undetectable Viral Load, Should We Still Use Condoms?

Having an undetectable viral load only prevents HIV transmission. Condoms protect against HIV, other sexually transmitted infections (STIs) and unintended pregnancy.

If you are unsure about whether your partner is undetectable, take steps to protect yourself from HIV, such as using condoms or taking daily PrEP (Pre-Exposure Prophylaxis).

You should never feel pressured to have sex without condoms.

If I Am on HIV Treatment, Should My Partner Be on PrEP?

Couples share the responsibility of preventing HIV. HIV-positive people and their partners should discuss how they can have a healthy, fulfilling and worry-free sex life, including using condoms, HIV treatment, PrEP or emergency PEP (Post-Exposure Prophylaxis).

You and your partner may decide that antiretroviral treatment for the HIV-positive partner provides enough protection against HIV. HIV-negative partners may choose to take PrEP, especially if they have other sexual partners; are unsure of their partner's viral load or their partner's ability to keep their viral load undetectable; or feel more secure in their sex lives with the added protection of PrEP.

What Else Can I Do to Prevent Getting or Passing HIV and Other STIs?

Get an HIV test. A positive test is an opportunity to treat HIV, stay healthy and prevent HIV transmission. A negative test gives you the chance to discuss ways to stay negative, like using condoms, taking daily PrEP or taking emergency PEP.

Get tested regularly for other STIs. STIs may not show symptoms, but they can increase an HIV-positive person's viral load, or make it easier for the virus to enter an HIV-negative person's body.

More Information

[Note from This article was originally published by the New York City Department of Health and Mental Hygiene in Dec., 2017. We have cross-posted it with their permission.]