A mathematical model representing the HIV epidemic among men who have sex with men (MSM) and transwomen in Lima, Peru as a test-case for the effectiveness of HIV pre-exposure prophylaxis (PrEP) was developed by Anna Borquez from Imperial College London and an international group of authors. This can be found in this week's PLOS Medicine
The model was used to investigate the population-level impact, cost, and cost-effectiveness of PrEP under a range of different scenarios. The authors found that strategic PrEP intervention could be a cost-effective addition to existing HIV prevention strategies for MSM populations. However, despite being cost-effective, a substantial expenditure would be required to generate significant reductions in incidence of HIV.