During the pandemic, there is a chance that someone will point an infrared thermometer at your forehead when entering an airport or doctor’s office to take your temperature. Your skin temperature will be measured to see if you have an elevated low body temperature or not, which indicates a fever, one of the main signs of COVID-19.
The good thing about infrared thermometers is that they are quick, easy, and non-invasive. You can quickly check many people without bothering them, e.g. B. Travelers moving through an airport or people entering a sports stadium. However, infrared thermometers also need to be accurate to be useful mass screening tools – and this is where problems arise.
Although fever is a key symptom of COVID-19, many infected people have no symptoms or develop a fever after becoming infectious, sick, and hospitalized. At least 11% of patients with COVID-19 do not have a fever, and only 43% of patients who are sick enough to be hospitalized have one. So finding a fever isn’t a foolproof approach.
While an infrared thermometer can accurately measure skin temperature, the real question is: Does the forehead temperature say anything about the low body temperature, the real sign of a fever? Under certain, highly controlled circumstances, an increased forehead temperature may indicate an increased low body temperature. This is why people put their hand on your forehead when you say you are not feeling very well.[Read: How Polestar is using blockchain to increase transparency]
The problem, however, is that the forehead or skin temperature can be increased or decreased regardless of body temperature for many reasons. Just been in a cold or hot environment, sunburn, just exercised, worn too many clothes, drank alcohol, just ate, had various skin diseases – all of these can affect the skin temperature.
Many factors that can affect skin temperature are common in our lives – such as drinking or exercising. giuseppelombardo / Shutterstock
Such factors can lead to false positive results where a fever is suspected if they don’t, and false negative results where someone passes a screening test but has a fever. None of the results are good. The former means that people need to be further screened or prevented from doing things. The latter means that infected people get access to places where they can spread the infection or feel free of the virus, so they don’t have to take any other precautionary measures, such as Wearing masks, social distancing or hand washing.
And even if an infrared thermometer could accurately identify people with an elevated body temperature, does this always indicate a fever? Again, the answer is obviously no. Other things can increase your low body temperature. The most obvious is movement, which is aggravated by being in a hot place and wearing too much clothing. Just like it can happen when you’re flying from one airport terminal to another to catch a connecting flight.
All of this has led the European Center for Disease Prevention and Control to conclude that, while some COVID-19 cases are detected through temperature control procedures at airports, the evidence suggests that such measures are not overall effective.
In the UK, the Medicines and Health Products Regulatory Authority has also warned that “temperature screening products, some of which are direct claims to screen for COVID-19, are not a reliable way to tell if people have the virus.” Agency for Medicines and Technologies in Healthcare also stated years ago that “the accuracy of infrared skin thermometers is ambiguous and requires more research”.
Since an accurate mass screening process is still required and infrared thermometers are already very popular, what can be done to improve their accuracy?
One way we’ve explored is to stick to the same kit but change the usage a little. We know that the body’s extremities are more reactive to the body’s overall thermal profile – for example, fingers raise or lower their temperature quite a bit when the low body temperature rises and falls a little. In contrast, the head – especially the corners of the eyes – is more even and reflects the low body temperature.
A look at these parts of the body and the temperature difference between them could provide a more accurate indication of whether the body temperature is elevated due to a fever. This would work because in many scenarios where the low body temperature rises, the temperature of the extremities rises as well – for example, playing sports, drinking alcohol, heating on too many clothes, etc. As a result, the difference between the temperature of the eye decreases and the finger off.
It’s clear to see: this new method would require two measurements, but would still be quick and easy. FernandoV / Shutterstock
But with a fever, the low body temperature rises, while the hands get colder, so the difference between eye and finger temperature increases. Therefore, a more accurate way to use infrared thermometers to screen for COVID-19 could be to measure the temperature of the hand and corner of the eye and determine the difference.
That wouldn’t be perfect. Other situations can increase this difference as well, including some age-related conditions. And as mentioned earlier, not all infected people develop symptoms of fever. But it would be a step in the right direction and therefore deserves further consideration. COVID-19 is unlikely to be the final pandemic, and we owe it to future generations to learn from this one what we can to prepare for the next.
This article by Mike Tipton, Professor of Human and Applied Physiology, University of Portsmouth, and Igor Mekjavic, Researcher in Automation, Biocybernetics and Robotics, Jožef Stefan Institute, and Associate Professor, Simon Fraser University, is published by The Conversation under a Creative Commons License republished. Read the original article.
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