During the current COVID-19 pandemic a large majority of public temperature measurements are being performed using non-contact thermometers. A new study published in the American Journal of Infection Control shows that in many cases these NCIT thermometers are not accurate enough and may even produce a false sense of security.

The study is called ‘Comparative accuracy testing of non-contact infrared thermometers and temporal artery thermometers in an adult hospital setting’. The study is the result of research by scientists Shahrukh Khan (PhD), Bridey Saultry, Scott Adams (PhD), Abbas Z. Kouzani (PhD), Kelly Decker (MN), Robin Digby (PhD) and Tracey Bucknall (PhD) of Deakin University, Geelong, Australia.

In their study they conclude: ‘This is the first study to compare accuracy of NCIT thermometers to TAT in adult patients. Although mass fever screening is currently underway using NCIT, these results indicate that the NCIT may not be the most accurate device for fever mass screening during a pandemic’.

Non-contact infrared thermometers – often called ‘IR guns’ or ‘infrared guns’ – are non-invasive thermometers for fever screening. Until recently there was no evidence of their accuracy for fever screening in adults. The now published Australian study is the first to do so. And the results of this study have serious ramifications for public health and family safety.

These are the results of the study. In 265 patients at two hospitals, a mean difference of ± 0.26°C was recorded between the NCIT (36.64°C) and the reference TAT (36.90°C) temperature devices. Bland-Altman analysis showed that NCIT and TAT temperatures were closely aligned at temperatures <37.5°C, but not at temperatures >37.5°C. NCIT had low sensitivity (16.13%) at temperatures ≥37.5°C. An AUROC score of 0.67 (SD 0.05) demonstrated poor accuracy of the NCIT device at temperatures ≥37.5°C.

In other words, at fever levels NCIT devices perform significantly less accurate compared to the reference temporal artery thermometer.

The results of the study show the non-contact infrared thermometers missed 5 out of 6 fevers. At the same time doctors and nurses around the world are fully aware of the fact that even during an unpredictable and escalating pandemic like the current COVID-19 situation there is just one constant in helping too ensure public safety: the ability to accurately screen for fever. To be able to do so public health officers in many countries rely on non-contact infrared thermometers of which many suspected they were not accurate enough. The Australian study published in the American Journal of Infection Control now proves that ‘infra red guns’ or ‘IR guns’ are not the best devices to screen for fever. With over 80 peer-reviewed study temporal artery thermometers are much better suited for public screenings because of their much better performance when it comes to accuracy and detecting fevers.

In their study the Australian scientists compared the accuracy of the Cocoon-NC9000 non-contact thermometer and the TAT-5000 temporal artery thermometer. The NCIT (Cocoon-NC9900) is a non-contact battery operated temperature measurement device that records body temperature or ambient temperature. It has a built-in infrared laser pointer. The NCIT is a factory-calibrated instrument that automatically calibrates in the first 15 seconds when the device is switched on for use. The TAT (an Exergen TAT-5000) also uses infrared technology to record temperature. Temperature is measured by gently moving the TAT across the forehead, and includes a momentary touch of the probe to the neck area behind the ear lobe, to account for any cooling of the forehead as a result of diaphoresis (sweat). The temperature of the skin surface (over the temporal artery) is measured used Arterial Heat Balance Technology (AHB). The TAT takes rapid sequential readings at up to 1000 measurements per second, and reports the highest temperature detected (peak) during the measurement course. The calibration of the TAT is established by an automation process through which the TAT instrument automatically self-calibrates each time the instrument is turned on.

This is the first study to compare accuracy of NCIT to a reference device TAT in adult hospitalized patients, the study concludes. ‘Although mass fever screening is currently underway using NCIT, these results indicate that the NCIT may not be the safest device for mass fever screening in adults if used in isolation during a pandemic. It should be noted that fever screening is often conducted in less controlled conditions than those presented in this study, which may result in further decreased accuracy than our findings. Additional research is required to compare its accuracy and precision to other invasive and non-invasive core body temperature testing methods’.