"A dynamic model of HIV transmission among people who inject drugs in Russia suggests that assuming a baseline HIV prevalence of 15%, increasing coverage of OST from 0% to 25% of all people who inject drugs could decrease HIV incidence by between 44% and 53%108."

Source

Merkinaite, S. A war against people who use drugs: the costs. Eurasian Harm Reduction Network (EHRN): Vilnius, Lithuania, 2012.