Having people stand in front of a scanner to have their body temperature read can lead to a large number of false negatives, allowing people with Covid-19 to pass through airports and hospitals undetected.
Instead, leading physiology experts have suggested that taking temperature readings of a person’s fingertip and eye would give a significantly better and more reliable reading and help identify people with fever.
The study, co-led by human physiologist and temperature regulation expert Professor Mike Tipton, is published in Experimental physiology.
If scans don’t give an accurate reading, we run the risk of wrongly excluding people from places they want or need to go, and we also run the risk of allowing people with the virus to spread the infection. not detected that they have.
Professor Tipton, University of Portsmouth
The study revealed four key factors:
- Temperature alone is not a good indicator of illness – not everyone with the virus has a fever and many develop only one after admission to hospital;
- Measuring skin temperature does not give an accurate estimate of deep (high in fever) body temperature. A direct measurement of deep body temperature is not practical;
- A high temperature, even taken from the deep body, does not necessarily mean that a person has Covid-19; and
- Taking two temperature readings, one in the finger and the other in the eye, is likely to be a better and more reliable indicator of a fever-induced deep body temperature increase.
Professor Tipton said: “Using a surface temperature scanner to obtain a single surface temperature, usually the forehead, is an unreliable method of detecting fever associated with Covid-19. Too many factors make measuring skin temperature a poor substitute for deep body temperature; skin temperature can change independent of deep body temperature for many reasons. Even though such a single measurement reliably reflected deep body temperature, other things, like exercise, can increase deep body temperature.
“The pandemic has had a devastating global effect on all aspects of our lives and, sadly, it is unlikely to be the last pandemic we are facing. It is essential that we develop a method to assess whether an individual has a fever that is accurate and rapid. “
The most common symptom of the 55,924 confirmed cases of Covid-19 reported in China through February 22, 2020 was fever, followed by other symptoms, including dry cough, sputum production, shortness of breath, muscle or joint pain, sore throat, headache chills. , nausea or vomiting, nasal congestion and diarrhea.
However, researchers say a significant proportion (at least 11%) of people with Covid-19 do not have a fever, and less than half of those admitted to hospital with suspected Covid-19 had a fever. Although the majority of positive cases develop a high temperature after being admitted to hospital, they were contagious before their temperature soared.
We think we can improve the identification of the presence of fever by using the same kit, but looking at the difference between eye and finger temperature – it’s not perfect, but it’s potentially better and more reliable. .
The same scanners can easily be adapted to perform these two measurements.
The new study argues that taking temperature readings of a person’s fingertip and eye would give a significantly better and more reliable reading and help identify people with fever.
A change in deep body temperature is a critical factor in the diagnosis of disease with an increase of only one degree indicating potential disease.
The many deep body temperature detection methods widely used in hospitals are too expensive, invasive, and time consuming to be widely used outside of hospitals.
Professor Tipton said: “During the SARS epidemic in 2003 there was a need for a rapid and efficient mass screening method and infrared thermography has become and remains the fundamental measure, despite concerns about its reliability.
A 2005 study of 1000 people comparing forehead temperature to three different infrared thermometers yielded different temperatures, ranging from 31 ° C to 35.6 ° C. On their own, infrared thermometer readings varied up to 2. ° C. In another study, more than 80% of 500 people tested by infrared gave a false negative result.
Such differences in skin temperature can be due to a variety of reasons, including whether the person has recently exercised, has an infection, is sunburned, or has recently been drinking alcohol, how far away a person is. a CT scan, how hot or cold the air is, how much fat a person has on their body and even their blood pressure.