Details of mathematical modeling of spread of HIV infection in Russia

The HIV transmission component of a previously published HIV and HCV transmission model[1] was adapted and used in this analysis, and is described in appendix 2. The model is divided into two intervention sub-groups:no opioid substitution therapy (OST) and OST. The IDUs in the OST group are assumed to have a reduced HIV transmission risk. Initially, the model assumes that no one is in these intervention states, but then after a certain time IDUs start being recruited onto OST. The model assumes a constant recruitment rate onto OST, and also assumes that IDUs leave OST at a constant rate. In addition, NSP is modelled simply such that after a certain point in time, the overall syringe sharing frequency of all IDUs is reduced by a certain factor. The model did not simulate the sexual transmission of HIV, as the focus of the study was on interventions aiming to reduce injecting risk.