The paper “Mathematical modelling of the influence of serosorting on the population-level HIV transmission impact of pre-exposure prophylaxis“, led by Linwei Wang and team, was recently accepted and published online in AIDS.
Patterns of “who has sex with whom”, such as serosorting, influence how HIV may spread and persist, and thus how interventions may fare among a population. Serosorting is a common practice among men who have sex with men (MSM) to reduce HIV risk via preferential partnership formation between individuals of the same perceived HIV status. We developed a mathematical model of HIV transmission to evaluate the influence of serosorting on the population-level impact of HIV pre-exposure prophylaxis (PrEP) in reducing HIV incidence among MSM in Canada. We found that ignoring serosorting in the model could underestimate the population-level HIV-incidence reductions due to PrEP. PrEP-mediated changes in serosorting (men on PrEP stopped vs. continued serosorting) could lead to programmatically-important reductions in PrEP-impact under low PrEP-effectiveness. Our findings suggest the need to monitor sexual mixing patterns to inform PrEP implementation and evaluation.