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Infectious Diseases

Updated 09 October 2020

Researchers calling for loss of smell to be recognised globally as Covid-19 symptom

Four out of every five people who experience a loss of smell test positive for SARS-CoV-2, making it one of the most prevalent symptoms.

  • Most guidelines call upon people to self-isolate and get tested if they experience a fever and/or cough
  • According to new research, emphasis should also be placed on a sudden loss of smell
  • Those with a loss of smell were more likely to test positive for SARS-CoV-2

When the Covid-19 outbreak started, most guidelines listed the main symptoms as fever, a cough and fatigue. But as the disease progressed, many people reported a variety of symptoms. One of these, loss of smell, was reported by may patients and is now recognised by the UK medical guidelines as one of the key symptoms.

New research also suggests that this symptom could be significant for guidelines and help medical professionals and potential patients to recognise Covid-19 more rapidly, which could spur on self-isolation and help curb the spread of the disease.

Loss of smell more prevalent than cough or fever

According to a new study published in PLOS Medicine, four out of five people experiencing a loss of smell and/or taste tested positive for Covid-19 antibodies, while 40% of those did not even experience a cough or fever.

The study was conducted by Professor Rachel Batterham and colleagues from the University of London.

While loss of smell and/or taste seems to be a key indicator of Covid-19, the link is not yet fully understood.

For their study, the team verified symptoms via telemedicine consultations and then performed an antibody test on 567 participants who experienced a loss of smell and/or taste.

Of these participants, 78% had antibodies. Those with a loss of smell were almost three times more likely to test positive for antibodies than those who lost taste. This suggests that this symptom should be taken seriously by policymakers globally, as most countries currently do not recommend self-isolating and testing when someone acutely loses their sense of taste or smell.

According to a previous study mentioned on Health24, it is important to note that the loss of smell as a result of Covid-19 differs from the loss of smell linked to any other respiratory condition such as a cold.

The main difference between loss of smell caused by Covid-19 and that of a cold is the way people breathe. People who lose their sense of smell as a result of Covid-19 are still able to breathe freely through their noses, but are unable to detect bitter or sweet tastes.

Indications for policymakers

Currently, many guidelines still urge members of the public to only self-isolate or test when they display flu-like symptoms.

Although the study has limitations, it strongly suggests that an acute loss of smell should be considered as a sign to isolate or test. It also suggests that there is an over-reliance on coughing and fever as the main Covid-19 symptoms.

Prof Batterham said, "Early self-recognition of Covid-19 symptoms by the members of the public, together with rapid self-isolation and PCR testing are vital in order to limit the spread of the disease. Currently, most countries around the world do not recognise a sudden loss of smell as a symptom of Covid-19."

READ | Loss of smell and taste might be long-term for some Covid-19 survivors

READ | Covid-19 and loss of smell: Harvard researchers uncover why it happens

READ | 4 unusual things we've learned about the new coronavirus 

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