A groundbreaking analysis published in The Lancet has brought a ray of hope to people living with HIV.
The study, presented at the 12th International AIDS Society Conference on HIV Science (IAS 2023), revealed that those who maintain low, but still detectible, levels of the virus and diligently adhere to their antiretroviral regimen have an almost negligible risk of transmitting HIV to their sexual partners.
The systematic review focused on the risk of sexual transmission of HIV at varying viral load levels. It found that individuals with viral loads below 1,000 copies per milliliter of blood, known as a suppressed viral load, had an almost zero risk of sexual transmission.
Moreover, those with an undetectable viral load, where the virus is not detected by the test used, had absolutely zero risk of transmitting HIV to their sexual partners.
This groundbreaking discovery prompted the World Health Organization (WHO) to issue a new policy brief alongside the research paper. The brief provided updated guidance on sexual transmission prevention and viral load testing for policymakers, public health professionals, and people living with HIV.
The aim was to further prevent HIV transmission and support global efforts to achieve undetectable viral loads through antiretroviral therapy for all HIV-positive individuals, preventing onward transmission to sexual partners and children.
In the past, research had indicated that individuals with viral loads below 200 copies/mL had zero risk of sexually transmitting the virus. However, the risk at viral loads ranging from 200 to 1,000 copies/mL remained less clear. This analysis sought to bridge that knowledge gap by thoroughly reviewing eight studies involving 7,762 serodiscordant couples from 25 countries. Serodiscordant couples are those where one partner is living with HIV.
The results were incredibly reassuring, with only two sexual transmissions of HIV detected among partners with viral loads below 1,000 copies/mL.
In both cases, the viral load test had been performed at least 50 days before transmission, suggesting that the individuals’ viral loads may have increased afterward. On the other hand, more than 80% of transmissions involved partners with viral loads greater than 10,000 copies/mL.
The study Lead author Laura Broyles, MD, of the Global Health Impact Group (Atlanta, USA), said: “These findings are important as they indicate that it is extremely rare for people who maintain low levels of HIV to transmit it to their sexual partners. Crucially, this conclusion can promote the expansion of alternative viral load testing modalities that are more feasible in resource-limited settings. Improving access to routine viral load testing could ultimately help people with HIV live healthier lives and reduce transmission of the virus.”
Antiretroviral therapy (ART) was highlighted as a crucial factor in reducing the virus’s amount in the body, preserving immune function, and lowering morbidity and mortality associated with HIV. Those not on ART can have viral loads ranging from 30,000 to over 500,000 copies/mL, depending on the stage of infection.
While lab-based plasma sample methods provide the most sensitive viral load test results, they may not be practical in certain regions. However, the study’s results supported the use of simpler testing approaches, such as dried blood spot samples, as effective alternatives for determining viral loads for clinical decision-making.
Co-author Dr Lara Vojnov, of WHO, said: “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. 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 destigmatise HIV, promote the benefits of adhering to antiretroviral therapy, and support people living with HIV.”
The study authors acknowledged some limitations in their research due to variations in data and definitions of ‘low viral load’ across the studies.
They also stressed that these findings did not apply to mother-to-child HIV transmission, which has different dynamics and exposure intensity during pregnancy, childbirth, and breastfeeding.
Writing in a linked Comment, co-authors Linda-Gail Bekker, Philip Smith, and Ntobeko A B Ntusi (who were not involved in the study) said, “Laura N Broyles and colleagues’ systematic review in The Lancet further supports the almost zero risk for sexual transmission of HIV at levels less than 1000 copies per mL…This evidence is relevant for at least three important reasons.”
“First, it highlights the need for viral load testing scale-up in all settings where people are living with HIV and taking ART…Second, as pointed out by Broyles and colleagues, these data are probably the best that we will ever have. Standard of care now requires that individuals are offered life-saving ART regardless of viral load…Third, and most importantly, this study provides strong support for the global undetectable equals untransmittable (U=U) campaign. This campaign seeks to popularise the concept that individuals with undetectable viral loads are not infectious to sexual partners, thereby reducing stigma and improving quality of life.”
In conclusion, the study’s findings supported the global campaign “Undetectable equals Untransmittable (U=U),” which aims to destigmatize HIV, promote the benefits of adhering to antiretroviral therapy, and reassure individuals that undetectable viral loads make them non-infectious to sexual partners.
This campaign holds the potential to significantly reduce stigma, improve the quality of life for people living with HIV, and contribute to the prevention of new infections.