Loss of smell 'highly reliable indicator of Covid-19'

1 October 2020, 20:30

Four out of five people with sudden loss of smell or taste tested positive for Covid-19 antibodies, new research has suggested.

The findings suggest an acute loss of smell or taste is a highly reliable virus indicator, scientists say.

They add that loss of smell or taste should now be considered globally as a criterion for self-isolation, testing and contact tracing.

Researchers at UCL and UCLH (University College London Hospitals NHS Foundation Trust) assessed health data from primary care centres in London.

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They found that 78 per cent of people who reported sudden loss of smell and/or taste at the height of the pandemic had Covid-19 antibodies.

Of these people, 40 per cent did not have a cough or fever.

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According to the researchers it is the first time such a figure has been calculated.

Lead author Professor Rachel Batterham, of UCL Medicine and UCLH, said: "As we approach a second wave of infections, early recognition of Covid-19 symptoms by the public together with rapid self-isolation and testing will be of vital importance to limit the disease's spread.

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"While people in the UK who experience sudden onset loss of smell or taste are advised to self-isolate and seek a test, at a global level few countries recognise this symptom as a Covid-19 indicator - most focus on fever and respiratory symptoms.

"Our findings show that loss of smell and taste is a highly reliable indicator that someone is likely to have Covid-19 and if we are to reduce the spread of this pandemic, it should now be considered by governments globally as a criterion for self-isolation, testing, and contact tracing."

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Between April 23 and May 14, researchers sent texts to people registered with a number of primary care centres in London who had reported sudden loss in their sense of smell and/or taste.

A total of 590 participants enrolled via a web-based platform and responded to questions about loss of smell and taste and other Covid-19-related symptoms.

Of these, 567 then had a consultation with a healthcare professional who confirmed the history of their symptoms and supervised a test to find out if they had coronavirus antibodies.

The study, published in PLOS Medicine, found that 77.6 per cent of 567 people with smell and/or taste loss had SARS-CoV-2 antibodies.

Of these 39.8 per cent did not have a cough or fever, and participants with loss of smell were three times more likely to have SARS-CoV-2 antibodies, compared with those with loss of taste.

Prof Batterham added: "Our research suggests a key public health message should be: people who notice a loss in their ability to smell everyday household odours such as garlic, onions, coffee, and perfumes should self-isolate and seek a coronavirus PCR swab test."