Non-contact infrared thermal imagers for mass fever screening--state of the art or myth?

During the severe acute respiratory syndrome (SARS) outbreak, the installation of non-contact infrared (IR) thermal image sensors (NCIRTIS) at national entry and exit points aimed to stop people with acute, febrile respiratory illnesses leaving and entering SARS-affected regions (Fig). This was done in line with WHO recommendations but the exact method of fever detection for exit and entry screening was not specified. This experience offers valuable information concerning the value of using the same detection methods for the impending avian influenza pandemic. Different types of IR sensors were employed but they all work under the same physical principles and are therefore prone to the same intrinsic errors.