Non-contact infrared thermal imagers may still be useful for mass fever screening.

To the Editor—We have some observations on the commentary by Wong and Wong on non-contact infrared thermal image sensors (NCIRTIS) for mass fever screening. Based on their literature review, the authors suggested that authorities should not rely on the use of NCIRTIS in mass fever screening. However, the authors overlooked a few recent studies, which may cast doubt on their conclusion. They pointed out that thermal screening failed to pick up a single severe acute respiratory syndrome (SARS) case during the 2003 epidemic. However, Chiu et al showed that infrared thermography as a mass fever screening measure successfully picked up 305 febrile patients from 72 327 outpatients and visitors of a hospital. Of these 305 febrile patients, three were confirmed to have SARS.