Low HIV Levels Linked to 'Almost Zero' Risk for Sexual Transmission

Lisa O'Mary

July 24, 2023

People with undetectable or very low HIV levels have zero or "almost zero" risk of transmitting the virus sexually if they are taking suppression medication, according to new guidelines from the World Health Organization.

The announcement was made concurrently with the publication over the weekend of definitive new research in  The Lancet. The findings were presented virtually at the 12th International AIDS Society Conference on HIV Science taking place in Brisbane, Australia.

The WHO estimates that 76% of the 39 million people worldwide living with HIV take antiretroviral therapy (ART).

"Antiretroviral therapy continues to transform the lives of people living with HIV," a WHO news release stated. "People living with HIV who are diagnosed and treated early,

Learn why it's so important to get tested and how to stop the spread of the virus.

The Lancet study showed that people who have a viral load of less than 1,000 copies per milliliter of blood have a tiny chance of transmitting the virus to sexual partners. Of 320 cases of transmission reviewed during the study, only two transmissions involved a partner with a load below that threshold. Those cases may have been impacted by viral loads rising between the time of testing and transmission. The previous guideline for zero risk of transmission was 200 copies per milliliter.

People living with HIV who do not take ART can have viral loads ranging from 30,000 to more than 500,000 copies per milliliter, according a summary of the study distributed by The Lancet to the media.

The new findings do not apply to the transmission of HIV from mother to child, including during pregnancy, childbirth, and breastfeeding.

"The ultimate goal of antiretroviral therapy for people living with HIV is to maintain undetectable viral loads, which will improve their own health and prevent transmission to their sexual partners and children," said researcher Lara Vojnov, PhD, diagnostics advisor to the WHO Department of Global HIV, Hepatitis and STI Programmes, in a statement. "But these new findings are also significant as they indicate that the risk of sexual transmission of HIV at low viral loads is almost zero. This provides a powerful opportunity to help de-stigmatize HIV, promote the benefits of adhering to antiretroviral therapy, and support people living with HIV."


World Health Organization: "New WHO guidance on HIV viral suppression and scientific updates released at IAS 2023."

The Lancet: "The risk of sexual transmission of HIV in individuals with low-level HIV viraemia: a systematic review," "People on ART with low but detectible levels of HIV viral load have almost zero risk of sexually transmitting the virus to others, in-depth review suggests."


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