Temperature Scanners Show Limited Value in Covid-19 Detection

There currently remains a need to easily, accurately and rapidly assess whether an individual has a fever.

A recent study conducted by investigators from the University of Portsmouth has found that body temperature scanners, like those used in Airports, can lead to a large number of false negatives. This can result in people being allowed to enter planes and hospitals undetected, furthering the spread of the coronavirus disease 2019 (COVID-19). The study was published in the journal Experimental Physiology.

"If scanners are not giving an accurate reading, we run the risk of falsely excluding people from places they may want, or need, to go, and we also risk allowing people with the virus to spread the undetected infection they have,” Michael J. Tipton, an author on the study said.

Investigators found that temperature alone is not a good indicator of disease, considering everyone who has the virus does not have one. Additional findings showed that skin temperature does not give an accurate estimation of someone’s deep body temperature, that a high temperature does not necessarily mean an infection with COVID-19, and that taking two temperature measurements can give a more accurate and reliable reading of a fever.

"Using a surface temperature scanner to obtain a single surface temperature, usually the forehead, is an unreliable method to detect the fever associated with Covid-19,” Tipton said. “Too many factors make the measurement of a skin temperature a poor surrogate for deep body temperature; skin temperature can change independently of deep body temperature for lots of reasons. Even if such a single measure did reflect deep body temperature reliably, other things, such as exercise can raise deep body temperature.”

The investigators argue that taking a temperature reading from an individual’s fingertip or eye can give a significantly more accurate reading of deep body temperature and will help to identify those with a fever. Changes in deep body temperature, even as small as 1 degree, are a key factor in diagnosing disease. The paper states that current scanners are easily able to be adapted to take the two measurements.

"We think we can improve the identification of the presence of fever using the same kit but looking at the difference between eye and finger temperature - it's not perfect, but it is potentially better and more reliable," says Tipton.