Loss of smell and taste as symptoms of COVID-19: what does the evidence say? – a lay summary
Since late March, a loss of the sense of smell (anosmia) has increasingly been discussed as a symptom in people with COVID-19. At the time, the Oxford Centre for Evidence Based Medicine’s look at this question concluded the evidence available was limited and inconclusive, but worthy of further investigation. Since then some new reports have emerged. So, are we getting any nearer to a definitive answer?
World Health Organisation included anosmia on a list of the disease’s “less common” symptoms on 17th April. Then on 18th May the UK Government added loss of smell and taste to the symptoms of coronavirus infection that should warn people to self-isolate for 7 days. Even taking into account the newest published research, the available evidence is still of poor quality, but we can cautiously agree that support for a link seems to be growing.
Re-analysis of the data reported in one published review finds anywhere between 30% to 80% of confirmed COVID-19 cases reporting loss of smell or taste. And data from ongoing symptom surveillance among UK and US users of the COVID Symptom Study smartphone-based app (originally called COVID Symptom Tracker) reports 65% of people testing positive for COVID-19 said they had lost their senses of smell and taste, while that symptom was found in only 22% of those testing negative.
To reduce uncertainty over this question we'll need data more of the kind of studies in which healthy users report daily to track their symptoms as they develop.
And remember, losing your sense of smell does not necessarily mean you have coronavirus. It could mean you have influenza, or just the common cold.
Mandy Payne, 21st May 2020
Disclaimer: the article has not been peer-reviewed; it should not replace individual clinical judgement and the sources cited in the original report should be checked. The views expressed in this commentary represent an interpretation by HealthWatch and do not necessarily represent those of Oxford CEBM, the NHS, the NIHR, or the Department of Health and Social Care. The views are not a substitute for professional medical advice.