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Body temperature scans too unreliable to detect Covid-19

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Taking body temperature scans to determine whether people may be infected with Covid-19 is unreliable, scientists have warned, suggesting it could allow individuals with the disease to pass through airports and hospitals undetected.

A team from the University of Portsmouth found multiple inaccuracies with such a test that they believe largely invalidates the results.

Firstly, they found that the temperature alone isn’t a good indicator of disease, as not all those who have the virus have a fever and many who do only develop one after admission to hospital.

The practice of measuring skin temperature also doesn’t give an accurate estimation of deep body temperature and a high temperature does not necessarily mean a person has Covid-19, anyway, the team said.

Taking two temperature measurements - one of the finger, the other of the eye - is likely to be a better and more reliable indicator of a fever-induced increase in deep body temperature.

Researcher professor Mike Tipton said: “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.

“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.

“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 pandemic has had a devastating global effect on all aspects of our lives and unfortunately it’s unlikely to be the last pandemic we face. It’s critical we develop a method of gauging if an individual has a fever that’s accurate and fast.”

The most common symptom of 55,924 confirmed cases of Covid-19 reported in China up to 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 diarrhoea.

However, the researchers say a significant proportion (at least 11 per cent) of those with Covid-19 do not have a fever and that fewer than half those admitted to hospital suspected to have the disease presented with a fever. Although the majority of positive cases go on to develop a high temperature after being admitted to hospital, they were infectious before their temperature soared.

Professor Tipton said: “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.”

Last week, a team at the University of Swansea announced they are developing a ‘smart patch’ containing the coronavirus vaccine that can be self-administered by patients.

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