WHO and the Center for Disease Control ( CDC ) assess risk and preparedness for a pandemic on a continuum of four pandemic phases ( alert , pandemic , transition , and interpandemic phases ) ( CDC 2016 , WHO 2010 ) . The time frame of our study corresponds to the alert and initial pandemic phases . During such a period , there is limited data about the accurate estimates of the virus transmissibility and severity , which are crucial parameters in understanding and predicting the course of a pandemic in epidemiology . Thus , we use available real - time data as proxy measures of consumers ' perceptions of risk severity and susceptibility to understand drivers of consumer mobility . The outcomes from our predictive model could be used as strategic inputs to improve several retail decisions even when there is limited data about virus transmission and severity .