Loss of smell is a “highly specific” symptom of coronavirus and may be a more reliable indicator of the disease than cough or fever, a study has found.
University College London (UCL) researchers polled 590 people who lost their sense of taste or smell earlier in the year.
Of those surveyed, 80 per cent had coronavirus antibodies, suggesting a previous infection.
Up to 40 per cent of the group did not report having a cough or fever.
Loss of smell or taste was added to the UK’s list of coronavirus symptoms, alongside cough and fever, in May.
Researchers found that those who experienced a loss of smell were up to three times more likely to have antibodies than those who lost only their sense of taste.
They said the findings suggest loss of smell is a “highly specific symptom of Covid-19”.
The study was constrained by the fact participants self-reported their symptoms and there was no control group.
However, researchers said the results showed health authorities should give loss of smell greater consideration when testing and treating coronavirus patients.
Many countries around the world still do not list loss of taste or smell as an official symptom of the disease.
Professor Rachel Batterham, lead author of the UCL study, 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.
“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.”
It is believed loss of smell occurs when the virus invades the cells found at the back of the nose, throat and tongue.
It differs from a cold where smell and taste might be affected by blocked airways.
The NHS advises people to get a test if “you've noticed you cannot smell or taste anything, or things smell or taste different to normal”.
Prof Batterham added: “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.”
