Smell and taste loss could help identify COVID-19 at airports, say researchers

Smell and taste loss associated with COVID-19 differs from that experienced by patients with common colds or flu, according to researchers who said the symptom could be used to quickly identify coronavirus infections in settings such as airports or emergency departments.

The study published in the journal Rhinology, was published as London's Heathrow Airport unveiled plans for a testing facility to replace quarantine measures.

Authors say it is the first to compare how smell and taste disorders in people with COVID-19 differ from those with other upper respiratory tract infections.

According to the research the main differences are that although COVID-19 patients also lose their sense of smell, they can breathe freely, do not tend to have a runny or blocked nose, and they cannot detect bitter or sweet tastes.

Authors added that findings lend weight to the theory that COVID-19 infects the brain and central nervous system.

The research team hope that their work could help develop smell and taste tests for fast COVID-19 screening – in places such as airports, primary care and emergency departments.

The research team from the University of East Anglia’s Norwich Medical School carried out smell and taste tests on 10 COVID-19 patients, 10 people with bad colds and a control group of 10 healthy people – all matched for age and sex.

Lead researcher professor Carl Philpott said: "We found that smell loss was much more profound in the COVID-19 patients. They were less able to identify smells, and they were not able to identify bitter or sweet tastes.

"In fact it was this loss of true taste which seemed to be present in the COVID-19 patients compared to those with a cold.

"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.”

Philpott noted that the sweet and bitter taste receptors affected by COVID-19 are known to play an important role in innate immunity.

"More research is needed to see whether genetic variation in people’s bitter and sweet taste receptors might predispose them to COVID-19, or conversely, whether COVID-19 infection changes how these receptors function, either directly or through a cytokine storm – the over-reaction of the body’s immune system," Philpott added.

This research was led by the Cliniques Universitaires Saint-Luc (Belgium), Université catholique de Louvain (Belgium) in collaboration with researchers at University of East Anglia/The Norfolk Smell and Taste Clinic at the James Paget University Hospital (UK), Aristotle University (Greece), Acibadem Taksim Hospital in Istanbul (Turkey), Biruni University (Turkey) and University Hospital of Foggia (Italy).