U=U is a simple, concise and impactful abbreviation for Undetectable = Untransmittable. It signifies that individuals with HIV, undergoing treatment and maintaining an undetectable viral load, cannot transmit the virus to an HIV-negative partner. U=U holds significant power in the battle against HIV stigma, raising awareness about the efficacy of antiretroviral therapies (ARTs) within communities and empowering people living with HIV in their sexual relationships. This groundbreaking movement has significantly contributed to reshaping perceptions about HIV and encouraging a sense of empowerment for people living with HIV.1

Watch an extract of one of our Science on the Sofa episodes to learn more about U=U.

The roots of U=U can be traced back to Bruce Richman and the Prevention Access Campaign (PAC), founded in 2016, with the mission of transforming the global understanding of HIV transmission. Bruce Richman has described U=U as a “simple equation (that) has profound implications for everyone living with HIV and for economies and governments around the world.” The PAC emphasised that achieving and maintaining an undetectable viral load plays a key role in preventing the transmission of HIV.2

“We now have the power in our hands to end the HIV epidemic by 2030.”

The U=U message is simple; if people living with HIV regularly take their medications, they can reach an undetectable viral load, preventing the transmission of the virus to their HIV-negative sexual partners. This holds true even in scenarios where condoms are not used and partners are not using pre-exposure prophylaxis (PrEP).1

While HIV stigma remains a global issue, U=U has played a key role in helping to fight against HIV stigma by reshaping societal attitudes and empowering people living with HIV. U=U addresses misconceptions that have allowed people living with HIV to engage in relationships without the constant fear of viral transmission. It serves as a powerful reminder of the impact of antiretroviral therapy (ART), encouraging individuals to pursue treatment, adhere to medication, and communicate openly about their HIV status in relationships.1 


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Understanding the global barriers to treatment, use, and adherence is crucial to making U=U a reality for all people living with HIV. In the words of Ben Young, Head of Global Medical Directors at ViiV Healthcare, U=U is not just a “warm fuzzy concept.”

“Communicating U=U really has the potential to benefit every step of the HIV care continuum – from testing to engagement in care to viral suppression, and quality of life.”

HIV stigma stands as an obstacle to treatment and U=U education. Bruce Richman has experienced first-hand the effects of HIV stigma. “When I was diagnosed, I was privileged to have access to quality healthcare, but because of my internalised HIV stigma, I only started treatment seven years later when I was in hospital. While today I’m out and proud about my HIV, back then I took the labels off my bottles and hid the medication in case anyone would discover I was living with HIV.”

He adds that “at least 10 million people around the world have yet to experience the life-changing personal and public health benefits of viral suppression.”

 “Understanding the barriers to treatment uptake and adherence for people around the world is vital if we are to finally make U=U a reality for all people living with HIV, which is the way to not only improve their quality of life but to eliminate new transmissions.”

At ViiV Healthcare, we advocate for access to medicines to address these challenges and help contribute towards making U=U possible for everyone. In this episode of Science on the Sofa, our ViiV community member Paulina Tshuma highlights the importance of spreading awareness and coming together as a “whole village,” educating everyone “about U=U globally.”


Undetectable HIV occurs when an individual’s viral load (the amount of virus detected in someone’s blood) is so low that it can’t be detected through standard blood tests. This is usually due to effective ART, where a combination of medications is prescribed to manage the progression of the virus.3 People living with HIV who have an undetectable viral load and use WHO-approved testing methods, including dried blood spot samples, can take their medication as directed without risk of transmitting HIV to their partners. To test for HIV using dried blood spots, a little blood is collected on special paper and allowed to dry. After drying, the blood spot is tested for HIV antibodies or the viral RNA/DNA.4,5

  • At what viral load is HIV undetectable?

    HIV viral load is categorised into three levels: undetectable, suppressed, and unsuppressed. As of January 2024, the Centres for Disease Control and Prevention (CDC) defines an undetectable viral load as having fewer than 200 copies of HIV per millilitre of blood. This signifies effective control of the virus. The WHO acknowledges that those with an undetectable viral load who consistently take their prescribed medication have an almost zero or negligible risk of transmitting HIV to their sexual HIV-negative partners.4

  • How long does it take to become HIV undetectable?

    The duration to reach an undetectable HIV viral load varies based on factors like overall health, medication adherence, and the chosen ART. Effective ART can lead to a rapid viral load reduction within a period of one to six months. A person is considered ‘durably undetectable’ when all viral load tests remain undetectable for at least six months after the first undetectable result. Achieving this status typically requires being on treatment for seven to 12 months.3

    Following an effective ART treatment plan as prescribed is important to reach an undetectable viral load. While U=U is a significant advancement in HIV prevention, achieving this may not be feasible for everyone due to socioeconomic factors, access to healthcare, and individual health conditions. Advocacy, education, and increased accessibility to HIV testing and treatment are essential to ensure that the benefits of U=U extend to everyone.

  • Can undetectable HIV become detectable?

    It is important to note that being HIV undetectable differs from being HIV negative. Despite having an undetectable viral load, the virus is still present in the body. If therapy is stopped, the viral load can become detectable once again. Maintaining consistency in taking medication is essential to sustain undetectability.4

    Detectability can also occur due to virological failure, which is the inability to achieve or maintain viral load suppression. HIV drug resistance can be another risk, potentially leading to detectable viral loads.4

    To prevent these risks, open discussions with healthcare professionals (HCPs) about treatment and adherence are crucial. Regular communication aids in tailoring effective treatment regimens, promoting adherence, and enhancing overall quality of life.6


According to the World Health Organisation (WHO), people living with HIV who maintain an undetectable viral load through any WHO-approved test and adhere to prescribed medication have an almost zero risk of transmitting HIV to their sexual partners. Several studies — including HPTN 052, PARTNER, PARTNER 2, and Opposites Attract — consistently demonstrate that daily adherence to ART leads to an undetectable viral load level. This resulted in low or zero sexual HIV transmission rates between individuals with undetectable HIV and their HIV-negative partners.7-10

This scientific evidence underscores the effectiveness of ART in preventing the sexual transmission of HIV when maintaining an undetectable viral load.

  • What does ‘untransmittable HIV’ mean?

    ‘Untransmittable HIV’ means that the virus cannot be acquired by a sexual partner, even in the absence of a condom and without the use of preventative measures, including PrEP. This is linked to maintaining an undetectable viral load through effective treatment and adherence to ART. Individuals with HIV, following prescribed regimens, have an almost zero risk of transmitting the virus to their sexual partners.1

  • Can a person with undetectable HIV transmit to their children?

    The risk of HIV transmission from the person who gave birth to their child during pregnancy, labour, and delivery is relatively low if the parent’s treatment starts well before delivery and undetectable virus levels are attained. Explore more about HIV in women with additional ways to manage the virus during pregnancy.11


Data from the Positive Perspectives Wave 2 study show the importance of people with HIV being informed about U=U by their HCPs. Global data from the study showed a wide variability of awareness across different genders and sexual orientations. Men who have sex with men had the highest awareness of U=U, while men who have sex with women had the lowest awareness.

The study also found that patients with HIV who were informed about U=U by an HCP had better mental, physical, sexual, and overall health outcomes compared to those who were not aware of U=U at all. This highlights the importance of having meaningful conversations about U=U and how they may positively impact health outcomes.9 Ben Young also emphasises the importance of community engagement.

 “[W]e must engage with people who distrust science and experts and help them reach a place where U=U is understood, accepted, and passed on. Or in other words, to beat the virus, we need messages that can themselves go viral.”

What are the benefits of U=U awareness?

After U=U, people living with HIV can experience a sense of relief and freedom from the stigma associated with the virus.U=U means that a person living with undetectable HIV who is on effective ART, cannot transmit the virus to their sexual partners, knowing this can reduce symptoms of anxiety, depression, and stress related to transmitting the virus. This, in turn, can improve overall mental health and well-being.5

The Positive Perspective 2 Research study found a “significant association between PLHIV who were informed about U=U by their HCPs and improved self-reported health outcomes.” Effective ART can reduce the risk of developing opportunistic infections and other complications due to a weakened immune system associated with HIV.12

Beyond viral suppression, U=U can also improve social outcomes for people living with HIV. U=U can help to reduce the stigma associated with HIV through communication with HCPs and those close to individuals living with HIV.5 Overall, U=U represents a significant milestone in the fight against HIV/AIDS. It provides hope for people living with HIV and can help to reduce the spread of the virus.

Watch Jose’s story and learn how he uses his experience to educate others about the importance of understanding treatment, adherence and having good communication with one’s healthcare team. In Jose’s words, having an effective treatment regimen felt like a “rebirth” and he “can’t express” how HIV medicines have changed his life.


  • How do you know if you have undetectable HIV?

    Undetectable HIV is determined through regular viral load tests. These tests measure the amount of HIV in the blood, and an undetectable result indicates that the virus is present at levels too low to be detected by standard tests.3

  • Can undetectable HIV be transmitted through blood?

    While the risk is significantly reduced, HIV undetectable transmission through blood may still be possible. However, the likelihood is minimal compared to higher viral loads, particularly in situations involving needlestick incidents and when comparing it to higher viral loads. Needlestick incidents refer to accidental injuries caused by needles, often occurring in healthcare settings. These incidents involve unintentional pricks with needles that may have been used on individuals living with HIV.10,13

  • Can undetectable HIV be transmitted through oral sex?

    The risk of transmitting undetectable HIV through oral sexual activities is extremely low. Safer practices, such as the use of condoms, can further reduce the risk.10

  • Can a person with undetectable HIV donate blood or sperm?

    Despite having an undetectable viral load, individuals with HIV, including those with undetectable levels, are generally restricted from donating blood due to the potential presence of the virus.14

  • Can an HIV undetectable mother breastfeed?

    The recommendation may vary, but generally, breastfeeding is discouraged when a mother is living with HIV, even if her viral load is undetectable. Alternative feeding methods are usually advised to eliminate the risk of transmission to the child.11

  • What is the life expectancy of someone with undetectable HIV?

    With effective treatment and maintenance of an undetectable viral load, people living with HIV are expected to have a normal life expectancy. Adherence to treatment plans, overall health, and addressing co-existing health conditions are crucial factors influencing life expectancy.15

  • Is there still a need to disclose your HIV status if you’re HIV undetectable?

    While undetectable HIV significantly reduces transmission risk, disclosure remains important for reasons related to law, ethics, and trust in relationships. If you are a healthcare worker, work in the military or in aviation, applying for health insurance, or donating blood, it is important to disclose your HIV status. If you are dating someone with HIV, it’s important to know that open communication challenges stigma, educates others, and empowers individuals. However, the decision to disclose is ultimately personal.16


U=U, undetectable=untransmittable; ART, antiretroviral therapy; PAC, prevention access campaign; PrEP, pre-exposure prophylaxis; WHO, world health organisation; CDC, Centres for Disease Control and Prevention; HCP, healthcare professional.

Exploring the power of U=U for HIV
Being empowered in your care


HIV prevention methods encompass a range of approaches that are both medical and non-medical. We believe a comprehensive approach, combining both of these alternatives, is key to creating a holistic prevention strategy.

Learn all about the diagnosis of HIV, including what HIV testing involves, understanding HIV test results and dealing with an HIV diagnosis.


  1. World Health Organisation. People living with HIV with an undetectable viral load cannot transmit HIV sexually. https://www.who.int/docs/default-source/searo/hiv-hepatitis/joint-moph-unaids-who-uu.pdf?sfvrsn=8378cd0_2
  2. Multinational Undetectable = Untransmittable (U=U) Call-To-Action. Prevention Access Campaign. Accessed 11th December 2023. https://preventionaccess.org/c2a/
  3. Gunn JKL, Patterson W, Anderson BJ, Swain CA. Understanding the Risk of Human Immunodeficiency Virus (HIV) Virologic Failure in the Era of Undetectable Equals Untransmittable. AIDS Behav. 2021;25(7):2259-2265. doi:10.1007/s10461-020-03154-z
  4. World Health Organization. The role of HIV viral suppression in improving individual health and reducing transmission. https://www.who.int/publications/i/item/9789240055179
  5. Tuaillon E, Kania D, Pisoni A, et al. Dried Blood Spot Tests for the Diagnosis and Therapeutic Monitoring of HIV and Viral Hepatitis B and C. Front Microbiol. 2020;11:373. Published 2020 Mar 9. doi:10.3389/fmicb.2020.00373
  6. Remien RH, Stirratt MJ, Nguyen N, Robbins RN, Pala AN, Mellins CA. Mental health and HIV/AIDS: the need for an integrated response. AIDS. 2019;33(9):1411-1420. doi:10.1097/QAD.0000000000002227
  7. Cohen MS, Chen YQ, McCauley M, et al. Antiretroviral Therapy for the Prevention of HIV-1 Transmission. N Engl J Med. 2016;375(9):830-839. doi:10.1056/NEJMoa1600693
  8. Rodger AJ, Cambiano V, Bruun T, et al. Sexual Activity Without Condoms and Risk of HIV Transmission in Serodifferent Couples When the HIV-Positive Partner Is Using Suppressive Antiretroviral Therapy [published correction appears in JAMA. 2016 Aug 9;316(6):667] [published correction appears in JAMA. 2016 Nov 15;316(19):2048]. JAMA. 2016;316(2):171-181. doi:10.1001/jama.2016.5148
  9. Rodger AJ, Cambiano V, Bruun T, et al. Risk of HIV transmission through condomless sex in serodifferent gay couples with the HIV-positive partner taking suppressive antiretroviral therapy (PARTNER): final results of a multicentre, prospective, observational study. Lancet. 2019;393(10189):2428-2438. doi:10.1016/S0140-6736(19)30418-0
  10. Bavinton BR, Pinto AN, Phanuphak N, et al. Viral suppression and HIV transmission in serodiscordant male couples: an international, prospective, observational, cohort study [published correction appears in Lancet HIV. 2018 Oct;5(10):e545]. Lancet HIV. 2018;5(8):e438-e447. doi:10.1016/S2352-3018(18)30132-2
  11. Eriksen J, Albert J, Axelsson M, et al. Contagiousness in treated HIV-1 infection. Infect Dis (Lond). 2021;53(1):1-8. doi:10.1080/23744235.2020.1831696
  12. Sadiq U, Shrestha U, Guzman N. Prevention of Opportunistic Infections in HIV/AIDS. [Updated 2023 May 22]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK513345/
  13. King KC, Strony R. Needlestick. [Updated 2023 May 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK493147/
  14. Blood Donor Counselling: Implementation Guidelines. Geneva: World Health Organization; 2014. Annex 5, HIV infection: information for blood donors. Available from: https://www.ncbi.nlm.nih.gov/books/NBK310571/
  15. May MT, Gompels M, Delpech V, et al. Impact on life expectancy of HIV-1 positive individuals of CD4+ cell count and viral load response to antiretroviral therapy. AIDS. 2014;28(8):1193-1202. doi:10.1097/QAD.0000000000000243
  16. Your voice. A guide to disclosure and HIV. HIV Scotland.  Accessed 12 December 2023. https://www.nat.org.uk/sites/default/files/publications/YourVoice.pdf

NP-GBL-HVX-COCO-240010 | February 2024

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