Serosorting and Seroadaptive Behaviours as HIV Prevention

A new term  "condomless anal intercourse"  (CLAI) replaces " unprotected anal intercourse" due to the acknowledgement that different strategies are used by MSM to reduce their risk of or " protect" themselves from contracting HIV when having sex without a condom. Some of the strategies include:

- Serosorting, such that HIV negative men only having CLAI with other HIV negative men

- Negotiating a regular ongoing relationship where both men are tested and if both are HIV negative they make an agreement not to have CLAI outside the relationship.

- Withdrawal method (of the penis prior to ejaculation)

- Strategic positioning during sex so that the HIV negative man takes the insertive role and the HIV positive man only takes the receptive role

- Viral load sorting, so that CLAI takes place only when the HIV positive partner's viral load is undetectable

- Pre- exposure prophylaxis (PrEP) used and the HIV negative person only engages in CLAI once he is taking ART on a regular basis

There were four presentations on this topic, the details of which can be seen in poster presentations at CROI. Some of their important observations include:

- The Centre for Disease control observed that  in the U.S. CLAI has increased between 2005 and 2014 in both HIV concordant and discordant sexual encounters. This trend was not different for men on or not on ART. It was not possible to conclude whether reliance on treatment explained the difference.

- in a Seattle seroconversion cohort of newly diagnosed MSM there was evidence of large and sustained serosorting behaviour changes which would have potential for reducing HIV transmission to HIV negative men.

- in a review of Philadelphian Local National Behavioural Surveillance data serosorting was common amongst African- American MSM but of limited safety because of the low level of testing, with 60% not having been tested in the last year

- in a Nigerian study looking at the use by MSM of sexual positioning and serosorting, undiagnosed HIV was present in 20% of those engaged in serosorting.

In the interesting question and discussion time some of the issues raised were:

- the need for collection of data which provides more detailed information about seroadaptive behaviours

- the need for clinicians to have conversations with patients about reducing risk of acquiring or transmitting HIV. There was acknowledgement that the most effective recent developments coming out of recent studies and presented at this conference support the impact of treatment as prevention and the goal of achieving and maintaining an undetectable viral load using cART in order to make HIV Transmission unlikely.

- regular/ frequent testing is essential for enabling early treatment and to reduce transmission but also to improve the effectiveness of serosorting behaviours. Clearly, serosorting in a context of low testing and high rates of undiagnosed HIV is a perilous strategy. 

- the acknowledgement that there is a problem with increasing STIs in HIV positive men, and also the problem that HIV avoidance behaviours are not the same thing as STI avoidance and hence don't mitigate that risk.

Some important findings pertaining to seroadaptive behaviours pertaining to viral load sorting and also to treatment as prevention can be seen in the interim results of the Opposites Attract Study, an Australian study lead by Andrew Grullich and Ben Bavington ( Poster 1019). The study aims to establish whether HIV transmission in homosexual HIV serodiscordant couples is greatly reduced when the HIV- positive partner is receiving combination ART and has an undetectable viral load, as has previously been seen in studies of heterosexual couples. To date the study reports that there have been no linked HIV transmissions in 150 couples over the 2 years follow up. This finding is extremely important and will offer considerable reassurance to gay serodiscordant couples having CLAI.