Cremin I., McKinnon, L., Kimani, J., et al. The Lancet HIV (February 2017), 4 : e214-222, doi:10.1016/
The authors developed a mathematical model to examine the optimal mix of interventions, including pre-exposure prophylaxis (PrEP), to reduce HIV incidence among a population of female and male sex workers (FSWs, MSWs) and men who have sex with men (MSM) in Nairobi, Kenya. The model showed that new infections likely will decrease from 5,110 in 2015 to 3,120 by 2030—however, the epidemic will likely be maintained among MSM. The authors provided 15 strategies that identify priority interventions (including increased condom use; improved retention in antiretroviral treatment, or ART; earlier ART; PrEP; and voluntary medical male circumcision) for each sub-population, along with the total anticipated cost of each strategy. The lowest-budget strategy was increasing condom use among MSW, followed by increasing condom use among MSM, increasing ART retention, and finally, expanding ART among all sub-populations. Prioritizing PrEP for the most vulnerable FSWs would improve the cost-effectiveness of the intervention, but would affect only a small FSW population. PrEP should be prioritized for the most vulnerable MSWs, then for MSM, and next for FSWs, as budgets allow. PrEP is less urgent for FSWs than for other populations, because of FSWs' high use of condoms. Ongoing incidence monitoring is required to determine future PrEP prioritization, especially given the high cost per infection averted.