Accuracy Matters


Why are Exergen thermometers more accurate than non-contact thermometers? 

Here are just a few reason why Exergen Temporal Artery Thermometers are more accurate than non-contact thermometers.

Published peer-reviewed clinical studies. Without such studies by medical professionals, there is no assurance of accuracy on children and adults in all settings.

Accuracy specifications by manufacturers of thermometers are laboratory accuracy, not accuracy in actual use on people being tested for fever. Laboratory accuracy tests do not include important physiological effects which vary from person to person, and setting to setting, which can affect the actual accuracy well beyond their laboratory accuracy.

Published peer-reviewed clinical studies are the gold standard for accuracy, since they include actual use on people in many settings, which automatically includes the physiological effects that vary from person to person and setting to setting. Only these studies can provide the assurance that the thermometer will provide accuracy in detecting fevers for all ages in all settings.

With more than 80 published peer-reviewed clinical studies attesting to the accuracy on all ages from newborns to geriatrics, in all settings where fever detection is needed, the Exergen Temporal Artery Thermometer is by far the most proven accurate, compared to thermometers which have no or very few clinical studies.

Why are no-touch thermometers less accurate?

No Touch thermometers are highly inaccurate for detecting fevers, here is why:

Accuracy specifications by manufacturers of No Touch thermometers are laboratory accuracy, not accuracy in actual use on people being tested for fever. Laboratory accuracy tests do not include important physiological effects which vary from person to person, and setting to setting, rendering No Touch thermometers unreliable, regardless of their laboratory accuracy. For No Touch devices, these physiological effects can overwhelm the normal laboratory accuracy of the device, to the point that its actual error is 2 deg C rather than 0.2 deg C.


Estimated standard deviation of temperature uncertainty

Physiological Variable

Est. Range

No-Touch Thermometry

TA Thermometry

Skin emissivity

0.97 ± 0.02



Skin ambient temperature




Variable perfusion on face




Perspiration on the face




95% confidence interval of errors clue to identifiable skin physiological variables


0.21 °C

This discrepancy in accuracy was clearly observed during the SARS epidemic in 2003. Exergen, recognized as experts in this field, was asked to provide the underlying science in a study regarding this accuracy discrepancy at a Symposium in 2004, which was subsequently published. The chart above is from that published study, and shows that the errors due to physiological effects is +/- 2.09 deg C.,compared to the light contact method of temporal artery (TA) scanning error of +/- 0.21 deg C. The TA thermometer was specifically designed to overcome these physiological barriers to obtaining accurate readings, and were awarded numerous patents on the design. (Pompei and Pompei 2004). Subsequent studies confirmed the Pompei findings of 2004.

In 2009, Bitar et al. reviewed 6 studies of fever screening with non-contact infrared thermometry (NCIT) devices, such as thermometer guns and thermal imagers. Across the reviewed studies, the sensitivity of NCIT ranged from 4% to 90% and its specificity ranged from 75% to 100%. In other words, NCIT detected fever in from 4% to 90% of the people with fevers, and NCIT did not detect fever in from 75% to 100% of people who lacked fever. The extremely wide range of reported sensitivities (4% to 90%) suggests generally poor usefulness of the NCIT methods, both because values at the low end of the range are unacceptably poor (4% of fevers detected), and because it is difficult to recommend a technology for which the user cannot tell if they will receive good (90%) or disastrous (4%) performance.

In 2019, Mouchtouri et al. reviewed the real-world efficacy of fever screening at airports and borders, and found that almost no disease cases had been caught across several nations and pandemics. The screenings were primarily performed with thermometer guns and thermal imagers.

It is now common knowledge in the professional medical community that No Touch thermometers are too inaccurate to use as a reliable screening device for fever, and are used largely for theater effects. An August 13, 2020 article in Forbes magazine quotes Dr. Anthony Fauci, director of the National Institute for Allergy and Infectious Diseases, as saying, when referencing infrared thermometers that take a person’s body temperature by aiming the device at their forehead, “We have found at the [National Institutes of Health] that it is much, much better to just question people when they come in and save the time, because the temperatures are notoriously inaccurate many times.

Without peer-reviewed published clinical studies, No Touch thermometers commonly available cannot be relied upon for medical accuracy in fever detection.

Exergen Corporation: New Data Confirms No-Touch Thermometers Miss Five Out of Six Fevers

First Study Comparing Accuracy of No-Touch Devices to Temporal Artery Thermometers has Serious Implications; Thermometer “Guns” Can Create False Sense of Security in Mass COVID-19 Screenings and at Home

As COVID-19 continues to set new records nationwide, the importance of understanding the difference in accuracy between temporal artery thermometers (TAT) and non-contact devices – now used widely for public temperature screenings – is of paramount importance. Non-contact thermometers are proven to be ineffective in measuring actual body temperature, while the accuracy of the TemporalScanner is supported by more than 80 peer-reviewed published clinical studies. This has serious ramifications for family health and public safety.

A new study in the American Journal of Infection Control is the first to compare the accuracy of no-touch thermometers to temporal artery thermometers. Australian researchers conducted a prospective observational study on a sample of 265 non-infectious patients at two hospitals. When body temperatures read below 99.5 degrees Fahrenheit, the thermometers showed similar results, but as temperatures rose above that, non-contact scanners’ accuracy decreased. Temperatures were farther apart as they rose. The non-contact scanners missed five out of every six fevers detected by Exergen temporal artery thermometers.

According to the authors, “This is the first study to compare the accuracy of non-contact infrared thermometers (NCIT) 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.”

“During this escalating and unpredictable pandemic, there is one constant in helping to ensure public safety: the ability to accurately screen for fever,” said Francesco Pompei, Ph.D., CEO of Exergen Corporation. “Non-contact thermometers are proven to be inaccurate in measuring core body temperature, yet they’ve been used extensively from the start of the pandemic, giving a false sense of security. In public settings, they are large ‘theater,” and as such their use should be seriously questioned. Only thermometers with extensive clinical studies, such as the Exergen TemporalScanner, can be trusted for accuracy during these threatening times of COVID.”

Twice Daily Temperature Checks at Home – What You Need to Know

In these times of COVID-19, checking for fever in the morning is not the most accurate time to detect a fever. Our daily circadian rhythm regulates our body temperature, which is lowest in the morning, and highest in the evening. New research shows this happens with fevers as well.

Up to 50% of fevers are missed in the morning, but none are missed in the evening due to circadian effects, making dinner time a good time for a second daily scan. Twice daily morning and evening fever detection is the best defense at home.

Exergen Twice Daily Resources

Medical information disclaimer: this document may contain general information relating to various medical conditions and their treatment. Such information is provided for informational purposes only and is not meant to be a substitute for advice provided by a doctor or other qualified health care professional. Readers should not use the information contained herein for diagnosing a health or fitness problem or disease, and should always consult with a doctor or other health care professional for medical advice or information about diagnosis or treatment.