Initially, two Taipei City Municipal Hospitals that kept electronic files of their emergency department patients' medical information were selected as pilot sites. From these two pilot hospitals, we had learned work flow involved in the process of data transfer, format of Chinese chief complaints, practical concern of ED (such as heavy workload etc.) during and after the 2003 outbreak of SARS, and available electronic ED information from nationwide emergency care hospitals. To obtain more representative data from various geographical areas, we gradually enlisted the cooperation of 189 hospitals nationwide, all offering emergency healthcare. Because many outbreaks of EIDs require emergency health care, these emergency care-designated hospitals were required transmit their ED triage and patient data to the Taiwan-CDC electronically on a daily basis ( Figure 1 ).