Covid: Loss of smell tests could be used to distinguish coronavirus from bad cold or flu, study finds

Researchers find coronavirus patients could not detect bitter or sweet tastes

The loss of smell that can be a symptom of a Covid-19 infection is “much more profound” than that experienced with a bad cold or flu, scientists have found.

Researchers from across Europe, including experts from the University of East Anglia, compared the experiences of loss of taste and smell for people with Covid-19 to those with other upper respiratory tract infections.

The small study, involving 30 people, also found that those who had the coronavirus could not detect bitter or sweet tastes, unlike those with the common cold or flu.

It is hoped that the findings, which have been published in the journal Rhinology, could help in developing smell and taste tests as a more rapid screening tool to distinguish Covid-19 infections from other forms of flu in the winter.

The UK government added loss of smell or taste to their list of coronavirus symptoms, alongside a fever or a new, continuous cough, in May.

People who have any of those symptoms have been told to self-isolate at home and get a test for Covid-19.

“This is very exciting because it means that smell and taste tests could be used to discriminate between Covid-19 patients and people with a regular cold or flu,” lead researcher Professor Carl Philpott, from University East Anglia's Norwich Medical School, said of the study.

"Although such tests could not replace formal diagnostic tools such as throat swabs, they could provide an alternative when conventional tests are not available or when rapid screening is needed - particularly at the level of primary care, in emergency departments or at airports.”

Concerns have been raised in recent weeks about how coronavirus cases can be separated from other illnesses with similar symptoms in the winter months, when common cold and flu infections are more likely.

The research team carried out smell and taste tests on 10 Covid-19 patients, 10 people with bad colds and a control group of 10 healthy people.

“We found that smell loss was much more profound in the Covid-19 patients,” Professor Philpott said.

“They were less able to identify smells, and they were not able to identify bitter or sweet tastes.”

He added that the findings provided further evidence for the theory that Covid-19 infects the brain and central nervous system.

“Our results reflect, at least to some extent, a specific involvement at the level of central nervous system in some Covid-19 patients,” he said.

Additional reporting by PA