Modeling the impact of interventions during an outbreak of HIV infection among people who inject drugs in 2012–2013 in Athens, Greece.

•Multiple HIV outbreaks have been documented among PWID since 2010.•A 150-fold increase in HIV incidence occurred over 2009–2012 among PWID in Athens.•HIV incidence declined by 89% in two years as a result of multiple interventions.•One third of HIV cases were averted over 2012–2013.•High coverage harm reduction programs and community-based interventions are essential.