Purpose of review: To discuss recent HIV epidemic models examining the transmission of antiretroviral (ARV) drug resistance.
Recent findings: A relatively small number of recent transmission models have investigated ARV resistance in the context of therapeutic, combined ART (cART); ARV-vaginal microbicides (ARV-VMB); and oral pre-exposure prophylaxis (PrEP). Models of cART use have highlighted potential concerns about future resistance transmission, particularly in resource-constrained settings, and have emphasized the benefits of viral load monitoring in limiting resistance spread. PrEP models have concluded that inadvertent use by HIV-infected individuals could increase resistance prevalence, and that risk compensation by PrEP users could limit their beneficial effects on HIV transmission. ARV-VMB models have demonstrated that whereas resistance can reduce prophylactic effectiveness in preventing HIV acquisition of female ARV-VMB users, it may concomitantly benefit users' male partners if the resistant strains that female users acquire are less transmissible than wild-type strains. The models have examined the balance between these two factors at the population level.
Summary: Recent HIV transmission models have adopted a wide assortment of structures and assumptions to explore drug resistance in the context of different ARV interventions in various settings. There is a need for future work emphasizing the simultaneous effects of multiple ARV interventions, as well as the public health impact of resistance, not just its prevalence.
aDepartment of Infectious Disease Epidemiology, Imperial College London, UK
bDepartment of Epidemiology and Center for Infectious Diseases, University of North Carolina at Chapel Hill, North Carolina, USA
Correspondence to Rebecca Baggaley, MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, St Mary's Campus, Norfolk Place, Paddington, London W2 1PG, UK Tel: +44 2075943288; fax: +44 2075943282; e-mail: firstname.lastname@example.org