Who will benefit from wide-scale introduction of vaginal microbicides in developing countries?
Dobromir Dimitrov (Fred Hutchinson Cancer Research Center)
(May 14, 2009 2:30 PM - 3:30 PM)
Vaginal microbicides (VMB) are currently among the few promising biomedical interventions candidates for preventing heterosexual transmission of HIV. They are specifically developed to help women reduce their risk of acquiring HIV infection. However, there are concerns that the next generation of microbicides containing ARV (ARV-VMB) may lead to the development of antiretroviral resistance and could paradoxically become more beneficial to men at the population-level. We aim to identify when and under what conditions the wide-scale use of VMB has a greater population-level impact among men than among women and to quantify the likelihood of male or female advantage in the benefits from the intervention under a wide array of utilization. We developed a deterministic model of HIV transmission to study the impact of a wide-scale population usage of VMB in a heterosexual population. Gender ratios of prevented infections and prevalence reduction are evaluated in 63 different introduction schedules of continuous and interrupted VMB use by HIV-positive women. The influence of different factors (VMB efficacy, transmission probabilities, etc.) on population-level benefits (e.g. infections prevented) among women and men is also studied through an analysis of 1,000 Monte Carlo simulations per scenario, using parameters sampled from ranges representative for the developing countries. Our analysis shows that VMB is still very much a female prevention tool. Effective control measures that restrict VMB-usage by HIV-positive women reduce significantly the risk of resistance development and further increase the likelihood of female advantage in VMB-prevented infections.