The impact of expanded age groups and other scenarios on incidence for the 2010 Tajikistan WPV1 outbreak. Arrows indicate the time of elimination in the model for each scenario. (a) Actual dates of outbreak response (oSIAs). (b) Impact of earlier oSIA rounds and preventive SIA rounds (pSIAs) in Spring 2009. (c) Hypothetical alternative outbreak assuming WPV1 introduction 30 days later.