Clients of female sex workers play a ‘fundamental role’ in South Africa’s HIV epidemic

A modelling study that assessed the impact of commercial sex, sex between men, and sex among heterosexuals on HIV transmission in South Africa suggests the clients of female sex workers are playing a ‘fundamental role’ in the epidemic.

In generalised HIV epidemics, such as South Africa’s, the contribution key populations make to HIV transmission is assumed to be small. But these findings suggest commercial sex plays an important part, with around 40% of HIV infections between 2010 and 2019 the result of sex between the clients of female sex workers and their non-commercial partners. This is the second-highest source of transmission, behind sex between what the study describes as ‘low risk’ heterosexual men and women. 

To arrive at these findings, researchers created a ‘dynamic’ model of HIV transmissions that happened among adults (ages 15-49) in South Africa between 2010 and 2019, based on data from national household surveys and key population surveys.

People were categorised as ‘low-risk females', ‘low-risk males', female sex workers, the clients of female sex workers, young men who have sex with men (aged below 30) and older men who have sex with men. People who inject drugs were not included as they have a small presence in the country. The model took changing rates of condom use, circumcision and antiretroviral treatment (ART) into consideration.

The findings suggest sex between low-risk men and women led to 59.7% of HIV infections in South Africa between 2010 and 2019.

Sex between female sex workers and their paying clients contributed 6.9% of new infections, while sex between the clients of female sex workers and their non-commercial partners accounted for 41.9%.

Sex between men contributed 5.3%, while sex between men who have sex with men and women contributed 3.7%.

The model accounted for people moving in and out of population sub-groups, meaning people can be in more than one category - which explains why the percentage contribution does not equal 100.

The study used a number of measures to calculate that 22% of adult men in South Africa buy sex. Although this is not a reliable size estimate, which potentially limits the finding, it is consistent with results from research in Nigeria and Benin that used similar methods.

The study found that increases in condom use have prevented five million HIV infections in South Africa since 1985, and ART has prevented three million since 2003.

Projections for 2020-2030 suggest scaling‐up ART for low‐risk individuals would avert around one in five new infections. But a similar impact and greater efficiency would be achieved by increasing ART among female sex workers and their clients, which could halve new infections in the next decade.

Client-focused interventions could recruit men through sex work venues or referrals from female sex workers. These interventions need to address poor uptake of ART, low levels of viral suppression and high levels of risky behaviours, such as casual sex and low condom use with non-commercial partners.

Yet while recommendations for client interventions exist, South Africa’s national HIV strategy does not include them and instead focuses on the sex workers themselves. Closing this gap could be key to controlling the country’s HIV epidemic.