Serosorting, sexual harm reduction and disclosure

Gus Cairns

The basic building blocks of HIV prevention - abstinence, monogamy and condoms - do not work for many people who are vulnerable to acquiring or transmitting HIV.

In the continued absence of other effective methods of reducing their risk, some people in the vulnerable communities have adopted a set of personal strategies to reduce risk which between them may be called ‘sexual harm reduction’ (SHR) by analogy with harm-reduction-based policies in injecting drug users.

The building blocks of SHR include:

  • attempting to restrict sex or unprotected sex to people of the same HIV status (‘serosorting’ or ‘negotiated safety’)
  • restricting unprotected sex to types of sex less likely to transmit the virus (‘strategic positioning’ and withdrawal)
  • restricting unprotected sex with HIV-positive partners to people who have an undetectable viral load.

The last strategy is considered separately in HIV treatment as prevention.

Sexual harm-reduction methods that take one’s own and one’s partners’ HIV status into account have also been called ‘seroadaptation’.

One feature of sexual harm reduction is that, unlike ‘ABC’ (abstain, be faithful, use a condom), these strategies also usually require two pre-existing conditions to be met for them to be effective:

  • people need to test frequently enough for HIV to know their status accurately
  • people need to disclose their HIV status and discuss it.

The extent to which people adopt these methods and whether they contribute to reducing HIV transmission, have no effect or even exacerbate it are very unclear, and evidence is often indirect or inferred. Even the degree of use of these strategies by gay men, the community in which serosorting was first investigated, is hard to establish. Different studies come up with very different answers as to whether, for instance, gay men take viral load into question when making decisions about condom use.

For instance, in a qualitative study from Australia in the year 2000,1 the researchers found that considerations of viral load, strategic positioning and withdrawal were already well integrated into gay men’s attempt to reduce the risk of HIV.

In contrast, in a qualitative survey of HIV-positive gay men conducted by Sigma Research in the UK, Relative Safety II, which was published in 2009,2 the researchers comment that: “Not one respondent described attending to the duration of anal intercourse, or to their own or their partner’s viral load, as a means of reducing the risk of HIV transmission”.

The number of men who serosorted was rather different: in this survey, about one-fifth of respondents reported always disclosing their status before sex and using serosorting as a method of sexual harm reduction:

“I would rather go with somebody and say ‘Right I am HIV positive, you are HIV positive, let’s do bareback sex…You know it’s done and dusted in like two minutes and there is none of all that which goes with it all and that ‘Oh I don’t want to do this and I can’t do that’. Have it out in the open and move on from that and just have good sex and then if you decide to meet again it’s a bonus. It’s as simple as that.”

Equally, however, other gay men relied on unreliable strategies such as inferring partners’ status from their behaviour:

You said that a lot of the guys you have sex with are positive. How do you know they are positive? Because they wouldn’t fuck without a condom otherwise would they? If I say ‘Can you use a condom?’, and I have told them, you know, that I am positive... I have had guys saying ‘Do you bareback?’, and I think, ‘well bareback, you know, he must be positive. If he wants to bareback me then fine. It’s no skin off my nose’.”

Part of the difficulty, then, in researching strategies like serosorting is that some strategies intended to reduce risk may be ineffective or even harmful. Another part of the difficulty is that respondents in surveys may not view such behaviours as socially approved, and may assume that researchers regard such attempts to minimise harm as a failure to maintain safer sex. As a result, respondents’ use of such strategies may not be volunteered unless specifically asked about.

Why doesn’t 'ABC' always work?

While abstinence, being faithful and condoms may have between them reduced the world prevalence of HIV to a great degree, they have not been enough to prevent all onward transmission. This is because as strategies they are simply incompatible with some people’s lifestyles or cannot be put into action.

Abstinence and sexual-debut delay is a personal choice which few people maintain for life.

Monogamy may be irrelevant if you are someone like a sex worker, or may be ineffective if your partner is not faithful.

Condoms may be unavailable, or either or both partners may be unwilling to use them. Condoms are the exception rather than the rule in primary relationships. Even if they can be used and are a social norm, as amongst gay men, people find 100% use hard to maintain.

Looking at newer prevention approaches, circumcision will initially only benefit heterosexual men and post-exposure prophylaxis is an emergency measure which is unlikely ever to make a public health impact on HIV prevalence.

Although we have had promising news on the efficacy or likely efficacy of microbicides and pre-exposure prophylaxis, they are unlikely to be generally available till 2014-2015 at the earliest.


 ‘Serosorting’ has been defined in at least six different ways:

  1. People restricting sex to people with their own HIV status.
  2. People restricting unprotected sex to people with their own HIV status.
  3. HIV-positive people restricting sex to other people with HIV.
  4. HIV-positive people restricting unprotected sex to other people with HIV.
  5. People whose last test was HIV-negative restricting sex to other people who have tested HIV-negative.
  6. People whose last test was HIV-negative restricting unprotected sex to other people who have tested HIV-negative.

For a number of reasons – which we will explore below – attempted serosorting by HIV-negative people (strategies E and F) has an inherent drawback that positive serosorting lacks: people can only be certain of their status up to the first time they risk exposure to HIV after their last negative HIV test. Research indicates that a large minority of people in high-risk communities who assume they are HIV-negative in fact have HIV.

The term ‘negotiated safety’ is sometimes used instead of ‘serosorting’ in HIV-negative people. The term usually implies testing and unprotected sex within a primary relationship, and usually indicates that the couple have agreed on other measures too, such as strict monogamy or restricting unprotected sex solely to the primary partner. 

There is abundant evidence that serosorting is practised by people with HIV from all communities, and some evidence from gay men and other high-risk communities that it has been adopted by HIV-negative people.

What is much less clear is whether it contributes significantly to a reduction in HIV incidence. While it seems logical that it would, it may be almost impossible to disentangle the effect of serosorting from the effect of a reduction in the average viral load in people with HIV (see HIV treatment as prevention). Some analyses (see below) have found it is associated with a reduction in the likelihood of HIV infection, especially if combined with other strategies, compared with taking no harm reduction action at all. Other studies have found no effect on the rate of HIV infections, however, and note that serosorters have much more sexually transmitted infections (STIs) than in people who use condoms. Amongst HIV-positive men, this may be because serosorting restricts unprotected sex to a closely connected pool or network of other HIV-positive gay men who may also have very high STI prevalence.

Some mathematical modelling studies (see below) have even suggested that HIV-negative serosorters in high-risk populations may actually have a higher risk of contracting HIV than people who have unprotected sex regardless of partners’ status. This is because in some populations there are a sufficiently high proportion of people who think they are HIV-negative, but who are in fact HIV-positive and have very high viral loads due to recent infection, so that they are actually more likely to transmit HIV than people who know they have HIV.

This conflicting evidence appears to reinforce the assertion above that serosorting is only likely to be effective in situations where the majority of people know their HIV status accurately and re-test regularly, and where HIV status is openly and frequently discussed and disclosed.

Other sexual harm reduction strategies

Although more research has gone into serosorting than any other way of attempting to reduce the risk of unprotected sex, people adopt other sexual harm-reduction strategies too at the same time as serosorting, and there is some evidence that these may have a synergistic effect (i.e. work better together than they would in isolation).

Strategic positioning involves gay men with HIV preferentially taking the passive (receptive) role in anal intercourse and HIV-negative men the active (insertive) one, because an insertive partner in anal sex is at less risk of contracting HIV from a positive partner than a receptive partner. Moreover, given that being receptive is a higher risk for HIV anyway, this may be a strategy that agrees with established sexual preferences anyway. There is some evidence that strategic positioning contributes to the effectiveness of sexual harm reduction, especially when combined with serosorting (see below).

Withdrawal - ejaculation outside the body rather than into vagina, rectum or mouth - has been practised as a last-resort birth-control (or possibly more accurately birth-reduction) technique amongst heterosexuals for years and has also formed part of safer-sex advice for gay men. The evidence that not allowing your partner to ‘cum’ in you reduces your HIV risk is weaker than it is for serosorting or strategic positioning, but one meta-analysis (see below) did find that it contributed to a reduction in HIV risk if combined with other strategies.

In the Australian study referred to above,1 early evidence was found, according to the researchers, that: “Epidemiological findings on risk appear to be informing the use of insertive/receptive positions to minimise risk in known or potential serodiscordant unprotected anal intercourse.”

One HIV-positive respondent commented: “I’m not good at stats and figures, but there’s a much higher chance of him [negative partner] becoming infected if I come inside of him as opposed to the other way around.”

By 2003, the Terrence Higgins Trust in the UK was incorporating information about the relative risks of such choices (first of all, in an awareness campaign, ‘Facts for Life’). They felt that, with an increasing number of gay men moving away from 100% condom use, it was important to provide accurate information on the topic.3

The drawbacks of sexual harm reduction

Nonetheless, the idea that serosorting can make a positive contribution to HIV prevention is a challenge to orthodox HIV-prevention approaches. Its adoption is unsurprising: it is understandable that, questions of stigma apart, people will base safer-sex decisions on the HIV status of their partners and may prefer to have sex with same-status people.

But whether to promote serosorting or, on the other hand, warn against it as a dangerous distraction from using condoms and a cause of poor sexual health in general, is a different question.

The value of serosorting may be questioned for a number of reasons:

  • Serosorting and the other strategies do not protect against other sexually transmitted infections, including hepatitis B and C, whereas condoms do.
  • Gay men with HIV, specifically, have much higher rates of other STIs than their HIV-negative peers, and this is probably due to their adoption of serosorting, rather than condom use as an HIV-reduction strategy.
  • People may be making decisions on the basis of inaccurate information or assumptions.
  • Serosorting relies on disclosure, something still only practised by a minority of gay men with HIV. In one unpublished survey by Gay Men Fighting AIDS, conducted in 2005, only 20% of respondents said they always disclosed their HIV status (positive or negative) to partners, 40% said they sometimes did, and 40% said they never did.
  • It is seen as diluting the ‘use a condom’ message and providing ways for people to rationalise unsafe behaviour.
  • People who serosort can do things that at first look like ways of wilfully increasing their HIV risk rather than reducing it. For instance, gay men who advertise for ‘bareback’ sex may seem to be nothing other than irresponsible. On the other hand, if ‘bareback’ is a code for ‘HIV-positive’, or if bareback discussions lead to disclosure of HIV status, the net result may be a paradoxical isolation of HIV within a specific group.

Moreover, all sexual harm-reduction strategies between men (for example strategic positioning and withdrawal) are likely to involve a considerably greater risk of HIV infection than protected sex does.

The debate around sexual harm reduction, then, centres on this dilemma:

  • Should prevention messages concentrate on the fact that these practices still involve considerable HIV risk, and certainly sexual-health risk, and should therefore be discouraged?
  • Or, since the people who use these strategies to minimise HIV risk are unlikely to be persuaded back to consistent condom use, should prevention messages encourage practices such as disclosure of HIV status that will allow the strategies to be implemented?


  1. Rosengarten M et al. Touch wood, everything will be OK: gay men's understandings of clinical markers in sexual practice. Monograph 7/2000, National Centre in HIV Social Research, University of New South Wales. See, December 2000
  2. Bourne A et al. Relative safety II: risk and unprotected anal intercourse among gay men with diagnosed HIV. London: Sigma Research, See, 2009
  3. Terrence Higgins Trust Facts for life. Campaign. Booklet is still available at, 2003
This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.
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