Large-scale fever screening based on infrared thermography for outpatients at tertiary medical center during COVID-19 pandemic: implementation and practical experience

To evaluate the clinical utility of a multi-step fever screening program using infrared thermography (IRT) for visitors to outpatient clinics at a tertiary care hospital during the COVID-19 pandemic. We conducted a single-center, retrospective study at The University of Tokyo Hospital between January and December 2022, when the Omicron variant was predominant. Outpatient visitors underwent a three-step screening at the main entrance, including IRT, axillary temperature measurement, and physician’s evaluation. Outcomes included the number of COVID-19 cases detected, the positive predictive value (PPV) of IRT, and its association with ambient air temperature. Of 570,076 asymptomatic visitors screened by IRT, 3900 (0.7%) had a body temperature ≥ 37.0 °C; among them, 483 (12.4%) had axillary temperatures ≥ 37.0 °C. In total, 115 visitors (0.02%) were evaluated by physicians, and 55 underwent PCR testing, of whom 2 tested positive. The PPV of IRT was 12.4% and showed a strong correlation with ambient temperature ( r = 0.93). The overall yield of IRT-based fever screening at a tertiary hospital was minimal, with only 1 COVID-19 case detected per approximately 285,000 (2/570,076). Our findings highlight the limited clinical utility of fever-based screening and emphasize the importance of carefully considering disease characteristics, environmental factors, and resource allocation in future pandemic preparedness.