Comparing the impact of increasing condom use or HIV pre-exposure prophylaxis (PrEP) use among female sex workers

Highlights

• To achieve the same impact on FSW HIV prevalence as increasing condom use by 1%, the coverage of PrEP has to increase by >2%.
• The relative impact of PrEP compared to condoms increases for scenarios where pimps contribute to HIV transmission.
• Condom promotion interventions should remain the mainstay HIV prevention strategy for FSWs.
• PrEP should only be implemented to fill prevention gaps where condoms cannot be used.

In many settings, interventions targeting female sex workers (FSWs) could significantly reduce the overall transmission of HIV. To understand the role HIV pre-exposure prophylaxis (PrEP) could play in controlling HIV transmission amongst FSWs, it is important to understand how its impact compares with scaling-up condom use-one of the proven HIV prevention strategies for FSWs. 

It is important to remember that condoms also have other benefits such as reducing the incidence of sexually transmitted infections and preventing pregnancy. A dynamic deterministic model of HIV transmission amongst FSWs, their clients and other male partners (termed 'pimps') was used to compare the protection provided by PrEP for HIV-negative FSWs with FSWs increasing their condom use with clients and/or pimps. For different HIV prevalence scenarios, levels of pimp interaction, and baseline condom use, we estimated the coverage of PrEP that gives the same reduction in endemic FSW HIV prevalence or HIV infections averted as different increases in condom use. 

To achieve the same impact on FSW HIV prevalence as increasing condom use by 1%, the coverage of PrEP has to increase by >2%. The relative impact of PrEP increases for scenarios where pimps contribute to HIV transmission, but not greatly, and decreases with higher baseline condom use. In terms of HIV infections averted over 10 years, the relative impact of PrEP compared to condoms was reduced, with a >3% increase in PrEP coverage achieving the same impact as a 1% increase in condom use. 

Condom promotion interventions should remain the mainstay HIV prevention strategy for FSWs, with PrEP only being implemented once condom interventions have been maximised or to fill prevention gaps where condoms cannot be used.

Below:  The relative impact of PrEP compared to condoms for decreasing the endemic FSW HIV prevalence (a) or averting HIV infections (b) after 10 years for different baseline FSW HIV prevalences, with no condom or PrEP use at baseline.

Below:  Sensitivity analysis on how the relative impact of PrEP changes for specific changes in model parameters

Full article at:   http://goo.gl/hsnL86

By:  Mukandavire Z1, Mitchell KM2, Vickerman P3.

• 1Social and Mathematical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK. Electronic address: Zindoga.Mukandavire@lshtm.ac.uk.
• 2Department of Infectious Disease Epidemiology, Imperial College London, London, UK. Electronic address: Kate.Mitchell@imperial.ac.uk.
• 3School of Social and Community Medicine, University of Bristol, Bristol, UK. Electronic address: Peter.Vickerman@bristol.ac.uk. 
• Epidemics. 2016 Mar;14:62-70. doi: 10.1016/j.epidem.2015.10.002. Epub 2015 Nov 12.

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