Only having sex with same-status partners is an HIV prevention strategy for 40% of gay men

'Condom serosorting', viral load less used
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A study from Seattle has found that only having sex with men of the same HIV status was by far the most common method of trying to avoid HIV in gay men who did not always use condoms, according to findings presented at the 21st Conference on Retroviruses and Opportunistic Infections (CROI).

This study found that 'condom serosorting' – being open to sex with serodiscordant partners, but always using condoms with them – was far less popular as a strategy, as was ‘seropositioning’ – being top (insertive) when you are negative, bottom (receptive) if you are positive.

The Seattle study did not report on ‘viral sorting’ – having unprotected sex with men with HIV if they have an undetectable viral load – but a study from Germany found that 10% of men with HIV there regarded themselves as non-infectious if they had an undetectable viral load and based their choices about sex on this belief.



Choosing sexual partners of the same HIV status, or restricting condomless sex to partners of the same HIV status. As a risk reduction strategy, the drawback for HIV-negative people is that they can only be certain of their HIV status when they last took a test, whereas HIV-positive people can be confident they know their status


In HIV, refers to the act of telling another person that you have HIV. Many people find this term stigmatising as it suggests information which is normally kept secret. The terms ‘telling’ or ‘sharing’ are more neutral.


A sexual risk reduction strategy for gay men having anal sex without a condom. Different sexual positions are adopted according to HIV status: the HIV negative man takes the insertive role (‘top’) and the HIV-positive man the receptive role (‘bottom’).



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. 


Receptive anal intercourse refers to the act of being penetrated during anal intercourse. The receptive partner is the ‘bottom’.

It found that men who used viral sorting were far less likely to disclose their status or talk about HIV. The Seattle researchers are collecting data on viral load and will report on this soon.

Serosorting in Seattle

The Seattle study was designed to find out whether the sexual risk behaviour patterns men disclosed in a typical behaviour survey were purposeful – that is, whether they were part of a considered HIV risk strategy. Between February and August 2013, researchers at the Seattle HIV/STI clinic asked gay male service users to fill in two separate questionnaires: one detailing their actual recent sexual risk behaviour (condom use, status of partners, sex role and so on) and the other asking them what sexual risk strategies they tried purposefully to use. Eligible men was anyone who was at least 18 years old, who who reported any sex with a man in the past year, and who spoke English.

Out of 1902 eligible men, 51% (964) completed both questionnaires, of whom 835 (87%) were HIV negative and 129 (13%) were HIV positive. The questionnaire asking about chosen strategy asked specifically whether they used one of these three strategies:

  • Strict serosorting, i.e. only having sex, with or without condoms, with partners of the same HIV status;
  • Condom serosorting, i.e. only having condomless sex with partners of the same status, but allowing sex with condoms with partners of opposite or unknown status;
  • Seropositioning, i.e. having condomless sex with partners of any HIV status but being the insertive partner (‘top’ if HIV negative or the receptive partner (‘bottom’) if HIV positive.

Fifty-five per cent of the men (both HIV positive and negative) reported some kind of seroadaptive behaviour, meaning that their choice of partner or behaviour was correlated in some way with their partner’s HIV status. Fifty per cent of HIV-negative men and 42% of HIV-positive men (46% on average) reported in the other questionnaire that this was part of a deliberate strategy. This means that 86% of men who showed seroadaptive behaviour agreed they were using it as part of a conscious strategy.

The researchers do not give details of the behaviour of the other 45% who were not 'sero-adapters' but, if consistent with other surveys, this would be a mix of men who did not have anal sex, men who maintained 100% condom use with all partners, and men who appeared to have no risk-avoidance strategy.

Strict serosorting was by far the most popular strategy of the three options listed by the researchers. The respective figures for those who were strict serosorters, condom serosorters, or 'seropositioners' were 42% of HIV-negative respondents for strict serosorting (with 39% saying it was their chosen strategy), 6.5% for condom serosorters (5.2% saying it was their strategy), and 7.1% using seropositioning (with 6.5% saying it was their chosen strategy).

Strict serosorting was less popular with HIV-positive men, with 32% doing it as behaviour and 25% as strategy, while the other two behaviours were more popular than in HIV-negative men, at 11% for condom serosorting and 10% for seropositioning.

This means that for 42% of HIV-negative and 33% of HIV-positive men, their main strategy for keeping themselves safe was to to restrict sex to people they knew or presumed to be of the same HIV status, or avoid sex with people who they knew to be of the opposite HIV status. This strategy was systematic and planned by 39% and 26% of them respectively. Strict serosorting was practised by 75% of HIV-negative men and 60% of HIV-positive men who had any sero-adaptive behaviour.

”Serosorting is overwhelmingly the most common seroadaptive behavior in our clinic,” comment the researchers.

Viral load in Germany

One strategy not considered by the researchers was ‘viral sorting’ – men basing condom use decisions with HIV-positive partners on whether or not they have a detectable viral load. At the conference, the interim results of the PARTNER study, which found no transmissions from anyone with HIV who had a viral load below 200 copies/ml, were big news.

A qualitative German study that asked 269 HIV-positive gay men whether they regarded themselves as uninfectious when they had an undetectable viral load found that 10% of HIV-positive men said they took this into consideration.

The researchers found considerable differences in condom use, STI risk and disclosure between men who adopted a 'viral sorting' strategy and other men with HIV. They found that 57.5% of viral sorters had had recent condomless sex compared with 36% of those who had not and that they were much more likely to say that they had had anonymous casual sex (70% versus 44%).

While these behaviours might not risk HIV transmission by people who really do have an undetectable viral load, they do lay them open to transmitting and acquiring other STIs. The researchers were also concerned that the adoption of a 'viral sorting strategy' seemed to involve discussing and disclosing HIV status much less. Only 19% of 'viral sorters' said they had recently disclosed their HIV status versus 42% of others, and only 22% said they had discussed the topic of HIV at all, versus 44% of others.

This study can’t determine whether gay men living with HIV are using their viral load knowledge to reassure themselves that they do not have to discuss their status with partners, or are using it as a post-hoc rationalisation for not having disclosed.

Either way, they suggest that when the original "Swiss statement" was published in 2008, it was assumed that viral load would be discussed as part of HIV status disclosure between partners, rather than being used as a substitute for discussion.

"Without open serocommunication in these settings, other – potentially asymptomatic – STIs may be passed on,” the researchers comment. “Thus, a subversion of a basic condition of viral load sorting seems possible.”

Given, however, what the Seattle study reveals – that HIV-positive men may meet with a flat rejection of sex by over 40% of HIV-negative prospective partners if they do disclose – it is perhaps understandable if some HIV-positive men regard "undetectable equals uninfectious" as primarily excusing them of an obligation to disclose.


Khosropour CM et al. Measuring purposefully adopted seroadaptive behaviors vs reported sexual behaviors among MSM. 21st Conference on Retroviruses and Opportunistic Infections (CROI), Boston, abstract 1032, 2014.

Kuhn E et al. Viral load strategy: impact on risk behavior and serocommunication of MSM in specialized care. 21st Conference on Retroviruses and Opportunistic Infections (CROI), Boston, abstract 1040, 2014.