The landmark Partner study that everyone is talking about—which tracked HIV transmission risk through condomless sex if the HIV-positive partner is on suppressive antiretroviral medication—has so far found not even one case of an HIV-positive person with an undetectable viral load transmitting the virus to a partner. But people in your everyday life may still be a little disbelieving.
“The most common response I get from disbelievers is that positive men use ‘undetectable’ as a way of getting people to sleep with them without a condom,” says Tyler Curry, an editor with the new group HIV Equal, who has written about his frustration with gay men still ignorant about what it means to be undetectable. “Positive men don’t want to transmit the virus to someone who is negative just as much as a negative person doesn’t want to become positive,” Curry emphasizes.
The Partner study itself comes with a series of warnings about what exactly the study has really found about undetectable viral loads. Researchers don’t recommend that undetectable gay and bi men have sex without the usual methods of protection, for example.
While some of this could be used as cover by skeptics, it also means positive people are left to understand and explain all of this science to a world that continues to stigmatize (and in some cases, criminalize) anyone with HIV.
Of the 1,100-plus couples taking part in the Partner study out of Europe, 40 percent are gay. This is the first time any study has so comprehensively investigated the risk of anal sex among men who have sex with men. To join, couples had to say up front that they sometimes don’t use protection—meaning no condoms, and the HIV-negative partner could not be on a daily PrEP, or pre-exposure prophylaxis, regimen.
In an analysis presented to the world in March at the annual Conference on Retroviruses and Opportunistic Infections in Boston, the study’s researchers also excluded any couple in which the HIV-positive partner’s viral load had gone above 200 copies per milliliter of blood. That’s the threshold at which they declared a person stopped being “undetectable.” Perhaps unnerving for anyone trying to keep their viral load down, that was the case for 16 percent of couples.
The first thing to understand about the Partner study is that some of the participants did contract HIV. Based on previous studies, researchers knew that odds were some of the negative partners would get HIV. So they put in place ways of identifying whether the undetectable partner had transmitted it to them.
Among gay men especially, the reality is that condomless sex outside of their primary relationship or marriage does happen with regularity. A third of the HIV-negative partners in gay couples reported having condomless sex with someone other than their primary partner, while just 3 to 4 percent of straight participants admitted the same thing. And what many experts already know about how HIV is transmitted still holds true: New infections usually come from people who are undiagnosed, who don’t know they have the virus, and who are not on treatment.
Partner researchers haven’t said exactly how many people contracted HIV during the study, promising only that the number would be released at a later date. But a phylogenetic analysis of the DNA from the strain of HIV showed it had not come from the undetectable partner. Meaning, the men who got HIV did so through someone other than their partner, who was undetectable.
More importantly, statistics show researchers should have seen 15 transmissions in straight couples and 86 in gay couples if partners hadn’t been on treatment. The chance of acquiring HIV from a partner who is undetectable very well might be zero. But that’s not what this study says, at least not yet.
The longer the study progresses and the more people who participate (Partner 2 starts this year and includes only gay couples), the higher confidence researchers can claim in their probabilities. Results so far are only preliminary and won’t be finalized until 2017.
The researchers themselves point out that their study isn’t the end-all for concerns about transmission. For example, they worked only with couples who said they hadn’t used condoms for two years, on average. Maybe transmission risk is greater the first time a serodiscordant couple has sex? They couldn’t know that from this study.
What researchers do is quantify levels of risk. A risk analysis published online in the journal AIDS in May attempted to make the basic point that risk accumulates over time, even if you’re using treatment as prevention. The chance of passing HIV to another person in a single year is less than it would be over a 10-year period, the study’s authors concluded, though they caution that the study is only a model and not meant to estimate actual transmission risk.
Partner researchers say a person with an undetectable viral load could indeed have zero risk of transmitting HIV. We’ve long known that it’s riskier to be the receptive partner during anal sex and that sex with ejaculation is riskier. So far researchers have also determined that the maximum possible risk for same-sex couples who have unprotected anal sex with ejaculation is only 4 percent, if the HIV-positive partner is on fully suppressive antiretroviral therapy. That small number is in itself big news.
Still, for some doubters it won’t make a difference.
“As far as dating goes, I don’t need to convince someone else that they are safe to date me because I am undetectable,” says Curry. “I give them the facts and they either accept them or they do not. Either way, I know what it means to be undetectable and I know that I am safe from ever transmitting the virus so long as I stay compliant.”
In Curry’s own relationship, he talked with his boyfriend about what it means to be undetectable when they first began dating. “But the topic quickly turned into a conversation about trust,” he said. “Undetectable, positive, negative, whatever…in a relationship, it is all about trust.”