Almost Zero Risk of Sexually Transmitting HIV From People on ART with Low Levels of Virus

Transmission of HIV has been an ongoing concern for people with detectable low-levels of the virus even when taking antiretroviral therapy (ART). However, a new study’s analysis finds that people in this category who adhere to their ART have almost zero risk of transmitting it to their sexual partners.

“These new findings are also significant as they indicate that the risk of sexual transmission of HIV at low viral loads is almost zero," study coauthor Lara Vojnov, PhD, said in a statement. "This provides a powerful opportunity to help destigmatize HIV, promote the benefits of adhering to antiretroviral therapy, and support people living with HIV.”

The study’s findings were published in The Lancet. This study was presented ahead of the International AIDS Society Conference on HIV Science (IAS 2023).

The authors pointed out the associated risks and uncertainty in the medical community when people who have a viral load of more than 200 copies per mL.

“Although it is generally accepted that HIV viral loads of less than 200 copies per mL are associated with zero risk of sexual transmission and this threshold is used for U=U messaging in many high-income settings,the risk at virus levels higher than 200 copies per mL has been controversial,” they write.

With this as the backdrop, the investigators conducted a systematic review and searched PubMed, MEDLINE, Cochrane Central Register of Controlled Trials, Embase, Conference Proceedings Citation Index-Science, and WHO Global Index Medicus, during the period of publishing from Jan 1, 2010 to Nov 17, 2022.

They analyzed 8 studies examining people who had low-level, detectable HIV and were on ART with more than 7700 serodiscordant couples with one partner living with HIV.

Of the 323 sexual transmissions of HIV detected across all eight studies, only two involved a partner with a viral load of less than 1000 copies/mL, the authors pointed out. In both cases, the viral load test was performed at least 50 days before transmission, suggesting individuals’ viral load may have risen in the period following the test. In studies that provided the full range of viral loads in partners with HIV, at least 80% of transmissions involved viral loads greater than 10,000 copies/mL.

Simplifying Testing
In terms of another key takeaway, this could make the case to expand testing to get more people in the continuum of care for HIV and get those who need it, beginning an ART regimen.

While using lab-based plasma sample methods provides the most sensitive viral load test results, such tests are not feasible in many parts of the world. However, the new findings support the greater use of simpler testing approaches, such as using dried blood spot samples, as they are effective at categorizing viral loads for necessary clinical decision-making.

“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,” the authors concluded.