ASHM Report Back

Clinical posts from members and guests of the Australasian Society for HIV, Viral Hepatitis and Sexual Health Medicine (ASHM) from various international medical and scientific conferences on HIV, AIDS, viral hepatitis, and sexual health.

MSM Practising Serosorting Behaviour

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Some data from the Opposites Attract Study was presented by Ben Bavinton of the Kirby Institute this afternoon. Probably well known to most readers this longitudinal study is examining HIV transmission and viral load in serodiscordant gay relationships. This data continues to be collected and wasn’t presented today. What was shown was data relating to whether  seordiscordant couples were having condomless anal intercourse when the positive partner’s viral load was perceived to be undetectable. The study includes  couples in Australia, Brazil and Thailand. Most of the positive partners in Australia and Brazil are on treatment with an undetectable viral load.


Two thirds of  Australian couples and just under half of Brazilian couples were not using condoms.  There was a strong association in Australia between this behaviour and the perception by the negative partner that the positive partner’s viral load was undetectable. This association was not evident in Brazil or Thailand. There is evidence therefore that Australian couples are comfortable with the Treatment as Prevention message. Ben thought that the reason for the high association in Australia compared to the other two countries was very likely due to the widespread discussion in the community around the issue, better understanding of the new findings and good communication with healthcare workers ,etc.


Another really interesting study in the same session looked at another seroadaptive behaviour seen in Seattle MSM at a Sexual Health Clinic.Researchers sought to examine whether HIV negative men were having condomelss anal intercourse based on the timing of when their casual partner reported having their last test. 86% participants reported  asking when the partner had last tested. Two thirds of participants had then chosen not to wear a condom on the basis of the answer.


A similar number of negative men had reported asking potential positive partners about what their viral load was. 83% decided not to use condoms on the basis of this.Those who did ask their partner about testing were less likely to then test positive for HIV but the numbers who tested positive for HIV were very small in this study so I’m not sure of the siginifcance.


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Guest Tuesday, 21 March 2023
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