The Infrared Fever Screening System (IFSS), conceptualised by Singapore's Defence Science and Technology Agency (DSTA) and Singapore Technologies Electronics during the 2003 SARS outbreak, is the first infrared-based system in the world to be used for fever screening of large groups of people. The IFSS does not measure skin temperature but uses a two-point detection concept to screen for fever. The first decision point is to sieve out probable febrile persons using thermal imagers and the second decision point is the confirmation that the subject has an elevated body temperature using conventional clinical thermometers. Statistics, physics and human physiology were key inputs in the design of the IFSS. Workflow and other operational considerations such as operator training are also important in ensuring the performance of the IFSS. This paper shares our experience in the development and deployment of the IFSS.