People living with HIV with an undetectable viral load cannot transmit HIV sexually

Bangkok, Thailand, 21 February 2020: The Ministry of Public Health of Thailand, UNAIDS and WHO endorse Undetectable = Untransmittable (U=U). As published in UNAIDS explainer Undetectable = Untransmittable, Public Health and HIV Viral Load Suppression, U=U means that people living with HIV who achieve and maintain an undetectable viral load, cannot transmit HIV sexually.

This concept is based on strong scientific evidence from four key studies (HPTN-052 study, PARTNER study, Opposites Attract, PARTNER 2 study) involving couples where one partner was living with HIV and the other was not. These studies did not detect a single case of sexual transmission of HIV from a virally suppressed person living with HIV to their HIV-negative partner.

With U=U, HIV treatment has transformed the HIV prevention landscape. Not only does HIV treatment have life-changing individual benefits by enabling people living with HIV to stay healthy, maintain their quality of life and have a lifespan similar to people not living with HIV, it is now recognized to have important population health benefits by interrupting transmission of HIV. U=U can also have enormous benefits in reducing stigma and motivating people living with HIV to test, start and maintain treatment, become virally suppressed and continue follow-up care.

In Thailand, an estimated 480,000 people are living with HIV in 2018, of which 451,384 (94%) have been diagnosed with HIV. Of these, 358,606 (79%) are on treatment and 269,715(75%) have an undetectable viral load. Closing the gap between the number of people living with HIV and the number with an undetectable viral load is crucial to ending HIV transmission in Thailand. To close the gap, HIV treatment is supported by a range of biomedical, behavioural and structural approaches within the combination prevention framework, including male and female condoms, pre-exposure prophylaxis (PrEP), post-exposure prophylaxis (PEP), harm reduction services for people who inject drugs, and HIV testing and linkage to care. In the era of U=U, condoms remain essential as they help prevent both STIs and unplanned pregnancy. By providing a range of different options, combination HIV prevention supports individuals to take control of their sexual health and reduce their HIV risk.

The Ministry of Public Health of Thailand, UNAIDS and WHO call for a continued emphasis on maximizing the impact of combination HIV prevention strategies; scaling up accessible, affordable and stigma-free testing and treatment services; and supporting better awareness of HIV-status, treatment adherence and access to viral load monitoring. Critically important are efforts in tackling stigma and discrimination which deters people living with HIV from accessing HIV prevention, treatment and care services. For this, it is important to raise awareness and promote the knowledge about U=U within the healthcare sector, communities, people living with HIV and other partners in the HIV response.

Contact details:

Dr. Sarayuth Uttamangkapong, Director, Division of AIDS and STIs, Department of Disease Control, Ministry of Public Health, Bangkok, Thailand, Tel. +66 2 590 3201, E-mail:

Dr. B. B. Rewari, Scientist HIV/AIDS/STI/Hepatitis, World Health Organization (WHO) South-East Asia Regional Office, Email:

Dr. Patchara Benjarattanaporn, UNAIDS Thailand Country Office, Tel. +66 2 680 4110, Email:

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