Actual (real-world) and counterfactual scenarios of varying levels of social and spatial inequity to providers of methadone were evaluated using HepCEP, a validated agent-based model of syringe sharing behaviors among people who inject drugs (PWID) in metropolitan Chicago, Illinois, U.S.A. Synthetic spatial distributions reflecting disparate geographic patterns of methadone provider location and population characteristics are evaluated to show how population-level health outcomes vary accordingly. The impact of the spatial distribution of methadone providers on syringe sharing frequency is dependent on access. When there are significant structural barriers to accessing methadone providers, distributing providers near areas that have the greatest need (as defined by density of PWID) is optimal.