The work of a couple: how gay men in relationships come to trust that “Undetectable = Untransmittable”

Having a relationship based on trust, commitment and familiarity helps Australian gay men rely on undetectable viral load as a means of HIV prevention, according to interviews with HIV-positive and HIV-negative members of serodifferent couples. Confidence in the protective power of an undetectable viral load is also strengthened by receiving consistent test results after repeated condomless sex, according to a qualitative study recently published in AIDS and Behavior.

Steven Philpot of the Kirby Institute interviewed 21 men who were taking part in Opposites Attract – one of the pivotal studies which demonstrated that HIV-positive people who have an undetectable viral load do not transmit HIV to their sexual partners. Although the first results of the PARTNER study had already been publicised at the time of the interviews (2015-2016), the study demonstrates that applying scientific data to one’s own life is not always a straightforward process. 

Philpot and colleagues suggest that health promotion organisations could help couples to navigate the issues by describing ‘viral load agreements’. Couples could be encouraged to negotiate a clear, spoken agreement, similar to the ‘negotiated safety’ agreements that are promoted to couples who have other sexual partners, they argue.

The study

Opposites Attract enrolled gay male couples in which one partner had HIV and the other did not (‘serodifferent’ or ‘serodiscordant’ couples). Participation was not restricted to couples with any particular HIV prevention strategy or sexual practice.



Having sex without condoms, which used to be called ‘unprotected’ or ‘unsafe’ sex. However, it is now recognised that PrEP and U=U are effective HIV prevention tools, without condoms being required. Nonethless, PrEP and U=U do not protect against other STIs. 


A serodifferent couple is one in which one partner has HIV and the other has not. 

post-exposure prophylaxis (PEP)

A month-long course of antiretroviral medicines taken after exposure or possible exposure to HIV, to reduce the risk of acquiring HIV.


Qualitative research is used to explore and understand people’s beliefs, experiences, attitudes or behaviours. It asks questions about how and why. Qualitative research might ask questions about why people find it hard to use HIV prevention methods. It wouldn’t ask how many people use them or collect data in the form of numbers. Qualitative research methods include interviews, focus groups and participant observation.


A serodiscordant couple is one in which one partner has HIV and the other has not. Many people dislike this word as it implies disagreement or conflict. Alternative terms include mixed status, magnetic or serodifferent.

For this qualitative sub-study, the researchers conducted in-depth interviews with 21 participants – ten were HIV-positive and eleven were HIV-negative. They came from 15 different couples and men were interviewed on their own, without their partner present.

Of the 15 couples, six were described as monogamous, four as non-monogamous, four as involving threesomes in which both men took part and one as ‘mostly monogamous’. The majority of couples lived in the same house or apartment and had been together for between one and five years. In all but two couples, the partner living with HIV had been diagnosed before entering the relationship.

The median age was 47 and most participants were white.

Changing practices

In the early stages of a relationship, condoms were thought of as natural and automatic. This was generally described as being true for all relationships (not just those in which HIV statuses differed).

Nonetheless, some couples had been especially cautious. This man’s HIV-positive partner had an undetectable viral load, but HIV had infringed on their sexual intimacy:

“At the moment of cumming, both of us would go, “We need to manage this. I don’t want to cum on you or you don’t want to touch it.” [Partner] would be precautionary… For example, he would warn me. He would push my hand away or push my head away.”

Through their connections to information sources including doctors, specialist websites, peers and the Opposites Attract study staff, couples learnt about the possibility of relying on an undetectable viral load as a prevention measure. In general, it was the HIV-negative partner that initiated or suggested sex without condoms. The HIV-positive partners were often apprehensive, as one of them explained:

“He told me he wanted to fuck me without condoms and I wasn’t prepared to let him because I was scared. But he was insistent, and I did want him to do that anyway. With a measure of reluctance, I agreed. And then we didn’t do it again. In fact, I waited until his next HIV test and I was a bit anxious about it.”

The HIV-negative partners often needed to reassure their partners that they were making a well-informed decision and that they were confident in what they were doing. Many asserted their responsibility for their own sexual health, so as to absolve their HIV-positive partner from feeling solely responsible for HIV prevention.

Though couples agreed together to stop using condoms, HIV-negative partners ultimately made the decision because they were the ones ‘at risk’. One partner living with HIV said:

“It was a mutual decision, but the ball was pretty much in his court”

Some couples tried sex without condoms, then went back to using them. It tended to be the HIV-positive partner who wanted to return to condoms. Just as HIV-positive partners were willing to please their partner and try sex without condoms, HIV-negative partners were equally willing to return to condoms. In negotiating unfamiliar territory, partners usually understood each other’s concerns and desires, and made compromises when the other had particularly strong feelings.


Interviewees talked about factors that helped them get used to relying on an undetectable viral load to prevent HIV transmission.

The fact of repeatedly having condomless sex helped men lose their apprehensions:

“What’s given me confidence is [partner] and I have been doing unprotected sex for a long time and he’s been okay.”

Men often experimented with condomless sex before it became a habit:

“We went through an extended period where sometimes we would [use condoms], sometimes we wouldn’t, and [partner] would get tested. This period must have lasted about nine months or a year with him not being positive, until we finally said, “I’d be buggered to it.””

Because they were taking part in the Opposites Attract study, couples were tested at least twice a year. The HIV-negative partner’s test results showed that he still did not have HIV and the HIV-positive partner’s test results showed that he was still undetectable. The researchers say that although couples knew based on scientific evidence that having an undetectable viral load was effective prevention, it was the act of physically seeing consistent test results that made the concept less abstract – it was proof that the strategy was working.

“As each year went on, you tended to worry about it less because I’d been with [partner] for a while and had many incidents of unsafe sex, and I was still negative, so I could see that the risk wasn’t high. The worry about catching something became less.”

Being in a strong, communicative relationship was an important factor ­– partners were committed to, trusted, and were familiar with each other. Men could be confident that their partner was taking the necessary steps for them to be confident in having an undetectable viral load. One HIV-negative partner explained:

“I know his personality and he’s structured and organised. But I also know that he takes responsibility for his part in my health and so I have faith and trust in him that if there was an issue with bloods, we would talk about it.”

HIV prevention was a ‘project’ in many relationships – something discussed and negotiated as a couple. Partners were confident that an undetectable viral load would work for them because they managed it jointly, and it was the manifestation of trust, commitment, and familiarity that facilitated mutual responsibility.

This was not the case when men had casual partners. Within his primary relationship, this HIV-negative man was happy to rely on his partner’s undetectable viral load. He had a different attitude with other sexual partners:

“[Partner] and I have trust and an understanding. But when you first meet someone and they tell you that [they are undetectable], then I’m like, “Yes, but I only just met you. So I don’t know your history. I don’t know who you are.””

Relying on an undetectable viral load for HIV prevention may be appropriate in ongoing, committed relationships with good communication, but less so in other contexts, the interviewees suggested. For HIV-positive men, it would mean asking a casual partner to trust them. For HIV-negative men, it would mean placing trust in someone they did not know well.

Continuing to use condoms

Three of the 15 couples continued to use condoms as their primary prevention strategy (none relied on pre-exposure prophylaxis (PrEP)).

One HIV-negative man said that he treated his partner’s semen as an “infectious substance” and avoided all contact with it.

One HIV-positive man said that he would like to rely on his undetectable viral load, but respected his partner’s concern about his own health:

“I say to him, “The chances of you getting HIV, because I’m undetectable, are practically zero,” but it’s not up to me. Would I like to have unprotected sex with him? Yeah. But it’s not on his radar… I know where he stands and it’s his body, and he should protect himself.”

A third couple mostly used condoms, but would sometimes have condomless sex for a short period of time. The HIV-negative man said that he would not allow his HIV-positive partner to ejaculate inside him without a condom, but that this was possible when the roles were reversed. Although they mostly used condoms and he frequently sought post-exposure prophylaxis (PEP), knowledge of his partner’s undetectable viral load did give him some sense of security:

“Now I understand more about HIV so I will fuck him without a rubber and I’ll blow in his arse. And that is through an understanding that he is undetectable.”

Viral load agreements

The couples in the study had worked out for themselves whether and how to rely on an undetectable viral load. Steven Philpot and colleagues suggest that a formal process which helps couples navigate this process might be helpful.

They say a ‘viral load agreement’ should cover:

  • discussing monogamy or otherwise
  • discussing the possibility of not using condoms within the primary relationship but maintaining condom use and/or PrEP with casual partners (if relevant)
  • regular viral load and HIV testing
  • regular STI testing for non-monogamous couples
  • the importance of medication adherence
  • ongoing communication about test results and these conditions.

“Viral load agreements are important because couples need to be assured, and to reassure each other, that undetectable viral load is being maintained and that they remain protected,” they argue.


Philpot SP et al. How Do Gay Serodiscordant Couples in Sydney, Australia Negotiate Undetectable Viral Load for HIV Prevention? AIDS and Behavior, online ahead of print, August 2018. (Abstract.)