U=U: A decade of progress, challenges and the work still to be done

Prevention in Focus PiF 2026 Spring

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A decade after the launch of the Undetectable = Untransmittable (U=U) campaign, its definitive message, that people living with HIV who maintain an undetectable viral load cannot pass it on through sex, has become a powerful tool for reducing stigma and improving the health and well-being of people with HIV. But while awareness of the message has grown, particularly among people living with HIV and gay, bisexual and other men who have sex with men (gbMSM), gaps remain in awareness of U=U and trust in it as a prevention strategy.

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This article reviews the benefits of raising awareness of U=U and explores awareness of the message across various populations in Canada. It provides information to help service providers to deliver U=U messages in clear, non-judgmental and inclusive ways.

U=U: from a grassroots campaign to a global movement

U=U began as a grassroots campaign to share the message that people living with HIV who are on treatment and maintain an undetectable viral load cannot pass HIV through sex.1,2 Evidence had been mounting for many years, including two rigorous scientific studies that proved that effective HIV treatment prevents sexual transmission.3,4 Recognizing the life-changing potential of this knowledge, a group of people living with HIV and their allies came together to form the Prevention Access Campaign. From this effort, the U=U slogan was born, and the U=U campaign was launched in 2016.

The Prevention Access Campaign and its supporters lobbied health organizations and governments to endorse the U=U message.2  Since the campaign was launched, more research has proven that there is zero risk of sexual HIV transmission when a person has an undetectable viral load.5–8 Grassroots advocacy efforts along with the growing body of evidence helped the campaign to gain momentum. CATIE endorsed U=U in 2017, and Canada became the first country to endorse the message in 2018.1  The U=U campaign has expanded into a global movement. Today, U=U is supported by over 100 countries and over 1000 organizations worldwide.1,2

Why raising awareness of U=U matters

Research shows that increasing awareness of U=U is associated with many positive outcomes, including: 

  • acceptance of one’s HIV-positive status2,9,10
  • reduced societal HIV-related stigma10,11
  • increased comfort with HIV disclosure and increased HIV disclosure12
  • improved overall health, including physical, mental and sexual health, for people living with HIV12
  • increased adherence to HIV medications and increased rates of viral suppression12
  • reduced anxiety around sex, including confidence in using U=U as the sole prevention strategy, and increased sense of normalcy, ease, empowerment and safety in the relationship in mixed-status couples13,14
  • increased access to sexual partners and less rejection from sexual partners based on HIV-positive status15

Healthcare provider awareness and communication of U=U

Healthcare providers can be important sources of accurate information about HIV and can help normalize conversations about U=U. However, many providers in Canada are not fully aware of the U=U message and do not discuss it with their patients. 

A 2023 Health Canada survey found that slightly over half (54%) of healthcare providers had heard of U=U, but only 18% felt they definitely knew about it.16 Awareness was higher among community-based providers (63%) than among those in clinics (52%) or hospitals (53%). Among healthcare providers who had heard of U=U, 97% agreed it is an important message to communicate to people living with HIV. However, more than a quarter (26%) said they never discuss U=U with their HIV-positive patients. 

Research has identified several reasons why healthcare providers might not discuss the U=U message with their patients. Some providers reported they hesitated to communicate the message because they were concerned that saying “zero risk” might overstate the science, choosing instead to describe the risk as “negligible” or “extremely low.”17 Others were less likely to initiate conversations if patients did not express interest in sexual health or raise the topic themselves.17 Providers also described encountering skepticism and HIV-related stigma from patients, which made U=U conversations more challenging, and noted that a lack of culturally relevant resources limited their ability to communicate the message in ways that were meaningful and affirming for diverse communities.17 Providers may also worry about unintended consequences, such as pregnancy and transmission of HIV or other sexually transmitted infections, if U=U is misunderstood as a replacement for all safer sex strategies.17,18

Ultimately, improving awareness among healthcare providers alone is not enough. Healthcare providers must be supported to understand the evidence behind U=U and to feel confident delivering clear, consistent and affirming messages.17 As sources of information, providers are in a powerful position to increase awareness and acceptance of U=U.

Awareness and trust in the U=U message among key communities

Awareness among people living with HIV

While research on awareness of U=U among people living with HIV in Canada is somewhat limited, existing data suggest that many people living with HIV are familiar with the message and about half of them have discussed U=U with their healthcare provider. 

A Canadian study of people living with HIV conducted in 2018–2024 found that 72% of participants reported they had heard of U=U.19 Awareness was significantly lower among straight and bisexual people and among people who had less than a high school education or were unemployed, and it was somewhat lower among people who identified as Indigenous.19

Canadian data found that 51%19 to 56%12 of people living with HIV had discussed U=U with a healthcare provider. People over 35 years of age were less likely to have had these discussions than younger adults, while Black people were more likely than White people to have discussed U=U with their provider.19

Awareness among specific communities living with HIV 

Awareness of U=U appears to be particularly high among gbMSM living with HIV in Canada. A national survey of gbMSM, Two-Spirit and non-binary people living with HIV in Canada found that 95% of participants reported being aware of U=U in 2018, rising to 98% in both 2019 and 2021.15

These high levels of awareness among gbMSM living with HIV are encouraging, but data are lacking for other communities. More needs to be done to understand awareness among other communities, such as women, trans people, African, Caribbean and Black communities, Indigenous peoples, and people who use drugs. To ensure everyone benefits from U=U, all people living with HIV need access to clear and accurate information about U=U, regardless of which communities they belong to.

Awareness among communities disproportionately affected by HIV 

Research on U=U awareness among communities disproportionately affected by HIV in Canada remains limited. Available studies suggest awareness is high among gbMSM, but it appears to be lower among Black and Indigenous communities. Data for other communities are lacking.

Among HIV-negative gbMSM, Two-Spirit and non-binary people taking pre-exposure prophylaxis (PrEP), awareness of U=U increased from 92% in 2018 to 96% in 2021 according to a national survey.15 Among those not on PrEP, awareness rose from 69% in 2018 to 78% in 2021. These findings suggest that awareness has grown among both groups over time, although it remains consistently higher among those on PrEP.  

Research shows that awareness varies among gbMSM who are HIV negative and whose HIV status is unknown. Those facing multiple forms of marginalization, such as transgender identity, racialization or lower income, were less likely to know about U=U, even after accounting for other factors (e.g., age, relationship status).20 Conversely, awareness of U=U was higher among those who knew their HIV-negative status, were ”out” to their healthcare provider, were single or in an open relationship, or had higher HIV risk based on standard assessment.20 These findings point to equity gaps in U=U awareness and the need for targeted outreach to reach HIV-negative gbMSM, especially those facing multiple forms of marginalization. 

Data from 2023 show low awareness among some racialized communities. Only 10% of Black people reported they had definitely heard of U=U, while 28% said they had vaguely heard about it. In contrast, only 5% of Indigenous people said they were definitely aware of the message.16 These gaps highlight the need for culturally relevant, community-led education to ensure all communities disproportionately affected by HIV know about and understand U=U.

Awareness among the general public

The limited data available for the general public show that awareness is much lower than among HIV-negative gbMSM and somewhat lower than among Black communities, but it is a bit higher than among Indigenous communities.

Canadian data indicate that in 2023, 19% of the general public had heard of U=U, including 6% who had definitely heard about it and 13% who vaguely recalled hearing about it.16 In 2025, awareness was reported at 20%.24 

In 2025, fewer than half of respondents from the general public said they were aware of the scientific evidence supporting U=U, and only 14% reported that their primary healthcare provider had ever discussed U=U with them.24 

Trust in the U=U message among key communities

While awareness of U=U has grown over the past decade, particularly among gbMSM and people living with HIV, awareness alone does not guarantee trust in the message. Studies show that many people who know about U=U do not fully believe or trust that a person with HIV who is on treatment and has an undetectable viral load cannot transmit the virus to sexual partners.18,21 This hesitancy, sometimes called “untransmittable skepticism,” is not only due to a misunderstanding of the science but is also shaped by stigma and mistrust, including mistrust of the message itself and, at times, of partners’ adherence to treatment.21,22 Early research with gbMSM in Vancouver (2016–2017) found that many interpreted U=U as “low risk” rather than “no risk.”21 Among those who were HIV-negative, some expressed uncertainty and ongoing fear about the possibility of transmission.21 Some participants reported that they continued to avoid sex with people living with HIV, or only had sex with condoms, despite being aware of U=U.21 However, more recent research with HIV-negative gbMSM on PrEP in Ontario (2020–2022) found growing trust that “undetectable” truly means “untransmittable.” This trust grew as the message became more widely accepted in the community.22 For many, this meant a greater willingness to engage in sex with people living with HIV.22 

Findings from a study conducted between 2016 and 2018 of people in a mixed-status relationship found that only half (53.2%) trusted U=U. This belief was similar across HIV status, with 49.0% of HIV-negative participants and 57.4% of HIV-positive participants reporting they believed in U=U.23 However, a more recent Canadian study (2018–2024) found that just over two-thirds (67%) of people living with HIV trusted the U=U message.19 

While acceptance of U=U appears to be growing among gbMSM and people living with HIV, findings from the general public tell a different story. In 2025, only 20% of Canadians considered the U=U message very believable, 20% found it moderately believable and 14% found it slightly believable. Prior awareness of U=U was the most important factor that predicted whether someone believed in the message.24

These findings show that awareness of U=U alone does not always translate into trust or acceptance. Skepticism can limit confidence in relying on U=U for sexual decision-making and can also impact many of the other benefits of U=U. Although we lack comparable data on awareness and trust among many populations disproportionately affected by HIV, a similar skepticism may be seen among populations that have not yet been studied. Therefore, long-term efforts to build awareness and trust are important across all populations. 

How service providers can effectively communicate the U=U message and maximize its benefits

Service providers can help to raise awareness of the U=U message by integrating U=U education into conversations with clients, regardless of their HIV status. It is important to communicate confidently and clearly that there is zero risk of passing HIV through sex when a person has an undetectable viral load.9 Service providers should be prepared to explain the evidence that supports U=U to clients who may be skeptical of the message because of misinformation or persistent HIV stigma.

Service providers can help close the gaps in U=U awareness by refining how the message is delivered. Tailoring education and outreach to specific communities, especially those underserved by the message, can make it more meaningful and effective. This includes using culturally relevant language and approaches and working in partnership with community members to ensure messaging resonates with their community’s cultural values, experiences and needs. 

When educating clients about U=U, it is important to recognize that not everyone is in a position to start or stay on treatment. Many people face structural and individual barriers, including multiple forms of stigma, racism, poverty and unstable housing, that can make it difficult or impossible to consistently engage in care and treatment. Advocates caution that the U=U message, if not delivered with care, can unintentionally reinforce stigma against those who do not have an undetectable viral load or who are not on treatment.9,25

Conversations should be grounded in respect, empathy and non-judgment. Providers can support people to start treatment when they are ready and help them stay engaged by addressing the broader social determinants of health that affect treatment access and adherence. This includes connecting clients to a range of services, such as housing supports, mental health care, peer support, harm reduction and income assistance, to build the foundation needed for treatment readiness and long-term success.

For clients who wish to start treatment or are having trouble adhering to treatment, service providers can provide support. This might include direct support such as help connecting them to a care provider, figuring out how to cover the cost of medication and developing strategies for adherence. It might also involve addressing broader social and structural factors in the person’s life that are barriers to getting on treatment and remaining engaged in care. 

U=U can also be a powerful advocacy tool for service providers. It reinforces the need for equitable access to HIV treatment and care so that everyone can benefit from reaching an undetectable viral load. It can also support calls to update laws and policies that can be used to criminalize HIV non-disclosure, by showing that the science no longer supports those legal approaches.26,27

Related resources 

The power of undetectable: How HIV treatment prevents transmission – CATIE client resource 

HIV Treatment to Prevent HIV – CATIE client resource

Undetectable = Untransmittable – video series by CATIE in partnership with the Prevention Access Campaign

HIV treatment and an undetectable viral load to prevent HIV transmission – CATIE fact sheet

Treatment as empowerment: Advancing HIV care with U=U – University of British Columbia self-directed course for healthcare providers

References

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  26. Hastings C, French M, McClelland A et al. Criminal Code reform of HIV non-disclosure is urgently needed: social science perspectives on the harms of HIV criminalization in Canada. Canadian Journal of Public Health. 2024 Feb;115(1):8-14.
  27. Canadian Coalition to Reform HIV Criminalization. Change the Code: reforming Canada's Criminal Code to limit HIV criminalization: a community consensus statement. Canadian Coalition to Reform HIV Criminalization, 2022. Available from: https://www.hivcriminalization.ca/reform-hiv-criminalization/wp-content/uploads/2022/08/3738_HIVLN_ConcensusStatement_EN-Digital.pdf

Externally reviewed by: Daniel Grace & Mark Randall

About the author(s)

Mallory Harrigan is CATIE's knowledge specialist, HIV testing. She has a master’s degree in community psychology from Wilfrid Laurier University.