‘Undetectable equals untransmissible’, or U=U, refers to the fact that people who take antiretroviral therapy for HIV daily as prescribed, and who achieve and maintain an undetectable viral load, cannot sexually transmit the virus to an HIV-negative partner.
(Australian Wording, U=U: ASHM Guidance for Healthcare Professionals)
People living with HIV on ART with an undetectable viral load in their blood have a negligible risk of sexual transmission of HIV. Depending on the drugs employed it may take as long as six months for the viral load to become undetectable. Continued and reliable HIV suppression requires selection of appropriate agents and excellent adherence to treatment. HIV viral suppression should be monitored to assure both personal health and public health benefits.
There is now evidence-based confirmation that the risk of HIV transmission from a person living with HIV (PLHIV), who is on Antiretroviral Therapy (ART) and has achieved an undetectable viral load in their blood for at least 6 months is negligible to non-existent.
(Negligible is defined as: so small or unimportant as to be not worth considering; insignificant.) While HIV is not always transmitted even with a detectable viral load, when the partner with HIV has an undetectable viral load this both protects their own health and prevents new HIV infections.[i]
However, the majority of PLHIV, medical providers and those potentially at risk of acquiring HIV are not aware of the extent to which successful treatment prevents HIV transmission.[ii] Much of the messaging about HIV transmission risk is based on outdated research and is influenced by agency or funding restraints and politics which perpetuate sex-negativity, HIV-related stigma and discrimination.
The consensus statement, addressing HIV transmission risk from PLHIV who have an undetectable viral load, is endorsed by principal investigators from each of the leading studies that examined this issue. It is important that PLHIV, their intimate partners and their healthcare providers have accurate information about risks of sexual transmission of HIV from those successfully on ART.
At the same time, it is important to recognize that many PLHIV may not be in a position to reach an undetectable status because of factors limiting treatment access (e.g., inadequate health systems, poverty, racism, denial, stigma, discrimination, and criminalization), pre-existing ART treatment resulting in resistance or ART toxicities. Some may choose not to be treated or may not be ready to start treatment.
Understanding that successful ART prevents transmission can help reduce HIV-related stigma and encourage PLHIV to initiate and adhere to a successful treatment regimen.
The consensus statement has been endorsed by:
Dr. Michael Brady – Medical Director of Terrence Higgins Trust and Consultant HIV Physician, London, UK
Dr. Myron Cohen – Principal Investigator, HPTN 052; Chief, Division of Infectious Diseases, UNC School of Medicine, North Carolina, USA
Dr. Demetre C. Daskalakis, MPH – Assistant Commissioner, Bureau of HIV/AIDS Prevention and Control New York City Department of Health and Mental Hygiene, New York, USA
Dr. Andrew Grulich – Principal Investigator, Opposites Attract; Head of HIV Epidemiology and Prevention Program, Kirby Institute, University of New South Wales, Australia
Dr. Jens Lundgren – Co-principal Investigator, PARTNER; Professor, Department of Infectious Diseases, Rigshospitalet, University of Copenhagen, Denmark
Dr. Mona Loutfy, MPH – Lead author on Canadian consensus statement on HIV and its transmission in the context of the criminal law; Associate Professor, Division of Infectious Diseases, Women’s College Hospital, University of Toronto, Toronto, ON, Canada
Dr. Julio Montaner – Director of the British Columbia Centre for Excellence in HIV/AIDS; Director of IDC and Physician Program Director for HIV/AIDS PHC, Vancouver BC, Canada
Dr. Pietro Vernazza – Executive Committee, PARTNER; Author, Swiss Statement 2008, Update 2016; Chief of the Infectious Disease Division, Cantonal Hospital in St. Gallen, Switzerland
The statement has also been endorsed by over 1,025 organizations from 102 countries
NOTE: An undetectable HIV viral load only prevents HIV transmission to sexual partners. Condoms also help prevent HIV transmission as well as other STIs and pregnancy. The choice of HIV prevention method may be different depending upon a person’s sexual practices, circumstances and relationships. For instance, if someone is having sex with multiple partners or in a non-monogamous relationship, they might consider using condoms to prevent other STIs.
“NEGLIGIBLE” = so small or unimportant as to be not worth considering; insignificant.