HIV factsheet: U = U for health professionals
Organization: Public Health Agency of Canada
Date published: November 2019
U = U (Undetectable = Untransmittable)
Early initiation of antiretroviral therapy (ART) improves overall health and prevents sexual transmission of HIV. The goal of treatment is to achieve and maintain an undetectable viral load. Studies have shown that effective ART prevents sexual transmission of HIVFootnote 1, Footnote 2, Footnote 3, Footnote 4, Footnote 5.
People living with HIV who take ART and who achieve and maintain an undetectable viral load have effectively no risk of transmitting HIV sexually.
Integrate U = U into routine HIV care
- Adherence to ART is essential for achieving and maintaining an undetectable viral load.
- It can take up to 6 months to achieve an undetectable viral load.
- Regular viral load testing is the only way to know if viral levels are undetectable.
- At least 2 consecutive undetectable results over a 6 month period are required before U = U can be used as a prevention strategy.
- An undetectable viral load does not prevent transmission or acquisition of other sexually transmitted infections (STIs).
- In addition to U = U, other highly effective ways of preventing HIV transmission/acquisition include condoms and oral pre-exposure prophylaxis (PrEP).
Condoms are the only effective strategy to help prevent other STIs.
Viral load: amount of HIV in the blood.
Undetectable: viral load less than 40 to 50 copies/ml and cannot be detected by standard tests.
Untransmittable: when an undetectable viral load prevents the sexual transmission of HIV.
Discuss the benefits of HIV treatment. U = U can transform lives and reduce stigma.
- Statement on behalf of the Council of Chief Medical Officers of Health
- Criminal justice system's response to non-disclosure of HIV
- Risk of sexual transmission of human immunodeficiency virus with antiretroviral therapy, suppressed viral load and condom use: a systematic review (CMAJ, PDF)
- The use of early antiretroviral therapy in HIV-infected persons (AMMI Canada, PDF)
- U = U: A guide for service providers (CATIE)
- Footnote 1
Cohen MS, Chen YQ, McCauley M, Gamble T, Hosseinipour MC, Kumarasamy N, et al. Prevention of HIV-1 infection with early antiretroviral therapy. N Engl J Med. 2011;365(6):493-505.
- Footnote 2
Cohen MS, Chen YQ, McCauley M, Gamble T, Hosseinipour MC, Kumarasamy N, et al. Antiretroviral therapy for the prevention of HIV-1 transmission. N Engl J Med. 2016;375(9):830-839.
- Footnote 3
Rodger AJ, Cambiano V, Bruun T, Vernazza P, Collins S, van Lunzen J, et al. Sexual activity without condoms and risk of HIV transmission in serodifferent couples when the HIV-positive partner is using suppressive antiretroviral therapy. JAMA. 2016;316(2):171-181.
- Footnote 4
Rodger AJ, Cambiano V, Bruun T, Vernazza P, Collins S, Degen O, 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.
- Footnote 5
Bavinton BR, Pinto AN, Phanuphak N, Grinsztejn B, Prestage GP, Zablotska-Manos IB, et al. Viral suppression and HIV transmission in serodiscordant male couples: an international, prospective, observational, cohort study. Lancet HIV. 2018;5(8):e438-e447.
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