In a statement from the UK Chief Medical Officer, it was advised that from 18 May, anyone who experiences a fever, persistent cough or anosmia (loss of smell), should self-isolate.
Evidence that anosmia might be an important symptom of COVID-19 has been highlighted in a press release by ENTUK which cites an increasing number of reports from different countries which suggest that loss of taste and smell are likely to be important symptoms of infection. For instance, one study from Germany found that among 200 COVID-19 positive patients, two in three reported loss of smell and taste. In addition, the mostrecent update from the COVID-19 symptom study in which patients have been using an app to document symptoms, suggest that losing a sense of taste and smell is a stronger predictor of COVID-19 infection than fever. Exactly how the virus causes these symptoms remains a mystery but one theory is that the virus causes inflammation in the olfactory epithelial cells which relay information on taste and smell to the brain.
Nevertheless, the recent deluge of research papers linking anosmia to COVID-19 would suggest that it is an important symptom that should not be ignored in assessing patients who might be infected.