Correction of human forehead temperature variations measured by non-contact infrared thermometer

Abstract

Fever is a common indicator for symptoms of infections, including SARS-CoV-2 or influenza. Non-contact infrared thermometers are able to measure forehead temperature in a timely manner and perform a fast fever screening in a population. However, forehead temperature measurements differ greatly from basal body temperatures and are the target of massive perturbations from the environment. Here we gathered a dataset of N=19392 measurements using the same precision infrared sensor in different locations while tracking both outside temperature, room temperature, time of measurement, and identity. From this, we propose a method able to extract and remove the influence of external perturbations and set a threshold for fever based on local statistics. This method can help manufacturers and decision-makers to build and use more accurate tools so as to maximize both sensitivity and specificity of the screening protocol.Abstract Figure

Variation of Forehead Temperature during Routine Working Shift in Hospital Laboratory Personnel: Implications for SARS-CoV-2 Screening

“…These findings may have important implications for systematic temperature monitoring in healthcare workers for purposes of screening infectious diseases (including COVID-19), whereby it may be advisable to adapt different ranges of “normal” forehead temperatures according to different periods of the day. Interestingly, Shajkofci reported a mean inter-individual forehead temperature variation between 1.9% and 2.3% with or without correction for environmental perturbations [ 12 ], which is nearly double than that found in our investigation (i.e., 0.9 ± 0.3%). We suspect this may be due to either the narrower period of forehead temperature monitoring in our study, or the more standardized environment, which suffered only modest indoor temperature variations (i.e., 1.4℃).…”

“…Rather different results were published by Zheng et al, who studied 10 healthy young subjects (mean age, 23 ± 2 years; 50% females) exposed to median-high air temperature (i.e., 28℃), and observed only a modest and clinically meaningless variation of forehead temperature between 9:00 AM and 3:00 PM (i.e., ∼0.1℃) (11). In a recent preprint, Shajkofci reported a progressive increase of ∼1℃ in mean forehead temperature from 8:00 AM to 1:00 PM in 19,392 subjects of unspecified age and sex [ 12 ].…”