Serosorting - HIV Risk Behavior

SAN ANSELMO, CA - NOVEMBER 23: Bottles of antiretroviral drug Truvada are displayed at Jack's Pharmacy on November 23, 2010 in San Anselmo, California. A study published by the New England Journal of Medicine showed that men who took the daily antiretroviral pill Truvada significantly reduced their risk of contracting HIV. (Photo Illustration by Justin Sullivan/Getty Images). Justin Sullivan/Getty Images News/Getty Images


Serosorting, or sero-sorting, is the practice of choosing whom to have sex with (or to have unprotected sex with), based on their serostatus -- i.e. whether or not they test positive for an infection. The term is primarily used in the context of HIV to describe the safer sex practices of men who have sex with men (MSM). However, serosorting also occasionally comes up in discussions of other viral STDs, such as hepatitis.

It is also not a practice limited to MSM, even their behaviors dominate most serosorting conversations.

In general, a person who is serosorting is trying to reduce their risk of contracting HIV. Some ways that individuals serosort include:

  • only having sex with partners who are assumed to be HIV negative
  • only having unprotected sex with HIV negative partners
  • only "topping" when there is a suspicion that a sex partner may be HIV positive (topping refers to being the partner who penetrates, rather than the partner who is penetrated. It is a somewhat lower risk position.)

While, in theory, this seems like it may reduce the risk of HIV, it is far from a foolproof method of HIV prevention. Among other things, serosorting assumes that people know their HIV status. In other words, it assumes that:

  1. partners have been tested since their last risky encounter
  2. the test took place long enough after their most recent risky encounter that a it will be accurate
  1. they are accurately disclosing their test results

However, some or all of these assumptions may be incorrect - particularly when looking at people who engage in a lot of casual sex. Most people simply aren't tested that regularly, and it can also be extremely difficult for individuals to disclose a positive test result.

In fact, one of the reasons that at home HIV testing may be helpful for individuals who want to serosort isn't the rapidity of the test results -- which may not be able to accurately identify a new HIV infection. Instead, home tests may be helpful because discussing testing can encourage people to disclose a previous positive test that they would not otherwise have mentioned.

Serosorting is safer than indiscriminately having unprotected sex. However, it's no substitute for condoms, if you're trying to avoid HIV. Unlike serosorting, condoms are highly effective at preventing sexual transmission of HIV, whether you're aware of your partner's status or not.

Carballo-Diéguez, A, et al. (2012) "Use of a Rapid HIV Home Test to Screen Potential Sexual Partners Prevents HIV Exposure in a High Risk Sample of MSM" AIDS 2012 Abstract TUPDC0304
Vallabhaneni S, et al. (2012) Seroadaptive practices: association with HIV acquisition among HIV-negative men who have sex with men. PLoS One. 7(10):e45718.

Also Known As: seroadaptive practices

Alternate Spellings: sero-sorting


One of the concerns that people have about the use of pre-exposure prophylaxis(PreP), for people who are at high risk of HIV because of their sexual behaviors, is that it might encourage people taking the drugs to have more unprotected sex than they would if they weren't lowing their HIV risk by using PreP. Since taking antiretroviral therapy reduces, but does not eliminate, the risk of acquiring HIV, this is quite a legitimate concern.

Although there has been only limited research on the issue, one study of how PrEP changes the behavior of MSM found that while the number of acts of unprotected anal intercourse did not increase overall, men who participated in the research did increase their use of sero-sorting techniques for deciding who they were willing to have bareback sex with. Study volunteers increased the number of times they had unprotected anal intercourse with men believed to be HIV negative, but they did not increase their risk behaviors with men of unknown status or those who were HIV positive.

Liu, AY et al. (2013) "Sexual risk behavior among HIV-uninfected men who have sex with men (MSM) participating in a tenofovir pre-exposure prophylaxis (PrEP) randomized trial in the United States. Journal of Acquired Immune Deficiency Syndromes. Publish Ahead of Print, POST ACCEPTANCE, 11 March 2013. Accessed May 5, 2013

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