The United Kingdom has added the loss of smell and taste to its official list of Covid-19 symptoms including fever and new continuous cough — a step that it hopes could help pick up about 2 per cent more cases of the novel coronavirus.

“From today, all individuals should self-isolate if they develop a new continuous cough or fever or anosmia,” the UK's four chief medical officers said in a joint statement.

“Anosmia is the loss or a change in your normal sense of smell. It can also affect your sense of taste as the two are closely linked.”

Other possible symptoms of Covid-19 include fatigue, diarrhoea, abdominal pain, or loss of appetite, but have not been included in the basic case definition.

By adding anosmia, the sensitivity of new case pick-up could increase to 93pc from 91pc with just new cough and fever, said Professor Jonathan Van Tam, England’s deputy chief medical officer.

When asked why the UK has lagged behind other countries in including the loss of smell in its official list, Van Tam said: “The question is: Which of those symptoms actually make the interception of cases better or worse?”

A major study by King's College London found that people with a positive test result were three times more likely to report loss of smell and taste than those who returned a negative test.

Report author Tim Spector said that Public Health England's (PHE) earlier insistence on only including fever and cough as major symptoms meant thousands of cases were missed.

The New and Emerging Respiratory Virus Threats Advisory Group concluded last month that loss of smell or taste should not be added to the symptom list, although The World Health Organisation and other countries including the United States now count it as a symptom.