Losing your sense of smell and taste may be the best way to tell if you have COVID-19, according to a study of data collected via a symptom tracker app developed by British scientists to help monitor the pandemic caused by the new coronavirus.
Almost 60% of patients who were subsequently confirmed as positive for COVID-19 had reported losing their sense of smell and taste, the data analysed by the researchers showed.
That compared with 18% of those who tested negative.
These results, which were posted online but not peer-reviewed, were much stronger in predicting a positive COVID-19 diagnosis than self-reported fever, the researchers at King’s College London said.
Of 1.5 million app users between March 24 and March 29, 26% reported one or more symptoms through the app. Of these, 1,702 also reported having been tested for COVID-19, with 579 positive results and 1,123 negative results.
Using all the data collected, the research team developed a mathematical model to identify which combination of symptoms – ranging from loss of smell and taste, to fever, persistent cough, fatigue, diarrhoea, abdominal pain and loss of appetite -was most accurate in predicting COVID-19 infection.
“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,” said Tim Spector, a King’s professor who led the study.