South Africa: sexual risk-taking not increasing with treatment as prevention roll-out
Disappointing results from the large-scale treatment as prevention trial in South Africa last year revealed no population level change in the number of new HIV infections – but new study reveals sexual behaviour isn’t to blame.
HIV treatment as prevention (TasP) did not increase sexual risk-taking behaviour in rural KwaZulu Natal province, South Africa, in the era of universal test-and-treat. TasP is where people living with HIV are put on antiretroviral treatment (ART) as soon as they test HIV-positive, for their own health, but also for population-level prevention.
Universal test-and-treat is now being rolled-out worldwide thanks to 2015 World Health Organization (WHO) guidelines that call for all people to be put on treatment irrespective of how healthy their immune system is – as guided by the number of white blood cells, called CD4 cells, that are present in the blood stream.
South Africa was one of the first countries in sub-Saharan Africa to initiate large-scale treatment as prevention (TasP) in their trial ANRS 12249, which aimed to find out the population-level effectiveness of test-and-treat. That is, not the effectiveness for the individual, but for reducing the number of new HIV infections in the whole population.
Last year it was revealed, disappointingly, that there had so far been no positive effect on HIV incidence in the country. Several reasons have been put forward to explain the results – including delays in linkages to care, which means that results may take longer to show, and mobile populations.
In sub-Saharan Africa, sexual heterosexual transmission largely drives the HIV epidemic, so it is important to understand any potential impact test-and-treat could have on risk-taking behaviour.
TasP trial participants were invited to respond to a socio-demographic and sexual behaviours questionnaire, administered face-to-face by fieldworkers/HIV counsellors as part of home-based survey rounds conducted every six months (2012-2016). Sexual behaviour data described the type, duration and sexual risks associated with up to the three most recent sexual partnerships in the last year.
More specifically, the questionnaire looked at seven indicators: sex in the last month; at least one regular sexual partner in the last six months; at least one casual sexual partner in the past six months and more than one sexual partner in the past six months; condom use at last sex with a regular partner, condom use at last sex with a casual partner; and estimates of concurrent relationships.
Researchers analysed sexual behaviours stratified by sex and over time, comparing those who had started ART immediately (test-and-treat) and those who had CD4-guided ART initiation.
There were no differences in sexual behaviour overall between the two arms. Where there were differences between arms, they were inconsistent and insignificant – sexual disinhibition was not observed for any of the indicators under study.
The authors concluded, “continued monitoring of population-level sexual behaviour indicators is needed as the UTT strategy is rolled out. In particular, multiple partnerships, partnership selection/dissolution, sero-sorting or “ART-sorting” phenomenon, which may also affect in the end the impact of ART on HIV incidence.”