Loss of smell, taste could be strongest symptom of Covid-19, say UK researchers

Loss of sense of smell and taste could be the best way to tell whether you have Covid-19, researchers have said.

Scientists at King’s College London have been tracking symptoms via their specially-created app.

By March 31, the Covid Symptom Tracker App had more than 1.8 million users sign up to log their symptoms, or lack thereof, daily.

Some 59% of the 1.5 million people who had signed up by March 29 and tested positive reported a loss of smell and taste, compared with 18% of those who tested negative, analysis of the data showed.

Researchers said the reports of those symptoms were much stronger in predicting a positive Covid-19 diagnosis than self-reported fever.

The team behind the app has now created a model featuring a combination of symptoms, including loss of smell and taste, fever, persistent cough, fatigue, diarrhoea, abdominal pain and loss of appetite, and said the strongest predictor is loss of smell and taste.

Commonly accepted symptoms of the respiratory disease include a fever, which NHS England says is usually a temperature of 38C or above, tiredness and a dry cough.

Under current Government guidance people are advised to self-isolate if they have a new continuous cough and/or high temperature.

The World Health Organisation (WHO) says other symptoms can include shortness of breath, aches and pains, and a sore throat.

Some people have also reported a loss of taste and/or smell, as well as abdominal pains.

Last week the WHO’s Dr Maria Van Kerkhove said there had been “quite a few” reports about people in the early stages of disease maybe losing sense of smell or taste but added “this is something that we need to look in to, to really capture to see whether this is one of the signs of Covid-19″.

Lead researcher Professor Tim Spector from King’s College, said: “When combined with other symptoms, people with loss of smell and taste appear to be three times more likely to have contracted Covid-19 according to our data, and should therefore self-isolate for seven days to reduce the spread of the disease.”

He said their research is helping to track where the virus is, before the effects are felt by the NHS, and encouraged people to continue or start logging their symptoms, even if they feel well.

Prof Spector said the data “gives us an evolving map of the UK of where symptoms are occurring two to three weeks before a strain on the NHS, which is why it’s vital to continue logging your health and symptoms, even when you feel completely healthy, and encourage others to use the app”.

The app has been developed by a King’s College London team in association with the Guy’s and St Thomas’ NHS Foundation Trust, NIHR Biomedical Research Centre and a healthcare start-up ZOE Global Limited.