Research has increasingly suggested that having an undetectable viral load significantly lowers the chance of an HIV-positive individual transmitting the virus to another. The latest results from the epic PARTNER study, published last week, found that after having condomless penetrative sex 58,000 times, HIV-positive people transmitted the virus to their partners a total of zero times.
Over the course of two years, the study tracked 888 serodiscordant couples — that is, couples in which one partner is HIV-positive and one is HIV-negative. This included 548 different-sex couples and 340 same-sex male couples. The HIV-positive partners maintained undetectable viral levels with antiretroviral therapy (ART), but the HIV-negative partners did not use PrEP.
There were 11 cases in the study in which partners contracted HIV, but they didn’t get it from their partners. Researchers tested the virus in each case and confirmed that what they had contracted was not phylogenetically linked to their partners’ virus. In other words, it was conclusively proven that they only contracted HIV because they had sex outside the relationship.
Simon Collins, a member of the PARTNER study steering committee, described the results as “simple to understand.” In a statement, he explained, “This provides the strongest estimate of actual risk of HIV transmission when an HIV positive person has undetectable viral load — and that risk is effectively zero.”
He pointed out that no study will ever actually prove that transmission is not possible, but “the results provide a dataset to question whether transmission with an undetectable viral load is actually possible.” The ongoing PARTNER 2 study focuses on same-sex male couples and will likely strengthen the results even further for gay and bi men.
This has significant implications for the outdated laws in many states that criminalize the nondisclosure of HIV. Activist Sean Strub of the SERO project described the way these laws target people living with HIV as threats and criminals:
Hundreds of people living with HIV in the US have been charged with criminal offences for the perceived or potential risk of HIV exposure or transmission. Some are serving or have served long prison sentences for spitting, scratching or biting and others for not being able to prove they had disclosed their HIV positive status before having sexual contact (even in the absence of any risk of HIV transmission). HIV criminalization has created a viral underclass in the law, further burdening a disenfranchised community, putting a disproportionate share of the shared responsibility for preventing sexually-transmitted infections on one party, and discouraging people at risk from getting tested for HIV.
Strub previously told ThinkProgress that the U.S. is far behind either countries in embracing research on HIV. It’s been nearly a decade, for example, since Switzerland’s HIV experts agreed that HIV-positive individuals undergoing ART are sexually non-infectious. But the various HIV criminalization laws in the United States punish everybody with HIV in the same way, regardless of their viral load or the riskiness of the sexual activity in which they engaged.