All the sentinel hospitals recruited into our system had independent MySQL servers on which their data were saved, plus a remote connecting program for automatic transfer of data. Data files generated by the 189 hospitals, including data from their triage classification systems, hospital information systems (HIS) and clinical information systems (CIS), were firstly de-identified and then transferred hourly to a Microsoft SQL Server 2000 at the Taiwan-CDC. Hyper text transfer protocol over secured sockets layer (HTTPS) or secured file transfer protocol (SFTP) was used in this process. All communication histories were recorded in a log file in the SQL server at the Taiwan-CDC and monitored daily by health informatics personnel. A program was written into the system so that each transfer attempt to the Taiwan-CDC would automatically generate an e-mail to the hospital notifying them whether the transfer had been successful or not.