Sixty seconds on . . . anosmia

Anosmia: wake up and smell the symptom

News reports from around the world have been noting sudden onset anosmia or ‘smell and taste’ loss as indicators of coronavirus for weeks. ENT specialists and family doctors in the UK are recognising that smell and taste loss could be a marker in asymptomatic carriers of the virus. In France, people with loss of taste and smell are being told to isolate even without the presence of the persistent cough and high temperature. In the UK, Chief Scientific Adviser Sir Patrick Vallance admitted at his Monday 30th briefing that "Loss of taste and smell is something that can happen with other respiratory viruses as well. It does seem to be a feature of this from what people are reporting and it is obviously something that people should take into account as they think about their symptoms." We would argue that there is now enough evidence to take this symptom much more seriously.

Anecdote must be heeded when it provides clues for researchers to follow. There are numerous high-profile media accounts of famous people experiencing smell and taste loss. Gary Linekar’s 28 year old son ‘necks a bottle of vinegar’ to show how off how his senses have been effected (Alex Wood, Daily Star Online, March 31); Broadway star Aaron Tveit was largely asymptomatic other than smell and taste loss but tested positive for the virus in mid-March (Hollywood reporter, March 23). Then there was Utah Jazz star Rudy Gobert (Jack Rathborn, Independent, March 23); Health minister Nadine Dorries and Dancing on Ice star Matt Evers (Sabrina Barr, Independent, March 23). In early March, ENT surgeons in the UK had begun to notice an increase in people attending surgeries for smell and taste loss. As reported in the Daily Telegraph, Prof Claire Hopkins, president of the British Rhinological Society, said "I saw nine young people with loss of sense of smell who were otherwise fit and well this month. That's extremely unusual, I might usually see one a month," (March 30). They subsequently put out a statement on loss of smell and taste as a marker for Covid-19 for researchers [1] and patients [2].

Meanwhile hard data continue to emerge. Just this morning (01/04/20) newspapers are reporting pre-publication findings from the 1.5 million users of Kings Colleges the Covid-19 symptom tracker app that 59% of those with a positive test for the virus reported loss of smell (and impact on taste) [3]. A survey of appr 10,069 Iranian subjects shows a correlation of 0.87 (p<0.001) with smell and taste loss [4], and an Italian smaller study again reports similar findings. The latter suggests what seems to be the emerging hypotheses around COVID-19 related anosmia, that is the binding of COVID-19 to ACE2 receptors (which are plentiful in the naso-pharyngeal tract) that accounts for the uniqueness of this symptom, and that it is not just secondary to a mucosal build up that could occur in any flu-like virus [5].

A further stand of evidence comes from the recently established Global Consortium of Chemosensory Scientists (Twitter @GCChemosensoryR) [6], an international team of clinicians and sensory scientists, who are currently working to understand reports of COVID-19 chemosensory issues. They have established a private Facebook group [7] as a discussion forum for anyone concerned about the relationship between smell/taste and appetite loss and Covid-19. In less than 7 days, with very little publicity, 700 people had become members and were reporting loss of smell (or ‘taste’) and deep anxiety about the symptoms. Reading through their posts, it is clear that anosmia is affecting otherwise healthy (and young) people all over the world and that in the cases where they have been tested for the virus, all are positive. Alarmingly, many of these reports indicate that people have had diminished taste/smell for days or weeks and are finding their concerns are not being taken seriously, are confused at government inactions and very few have been given advice to self-isolate.

The ENT-UK position statement advising people to self-isolate based on anosmia released on 24th March has not yet changed the official position [8]. We acknowledge that the research cited here is just published or pre-publication, and that anecdote is a precarious basis for decision, but taken together with the worldwide reports of sudden onset anosmia from China, South Korea, Iran, Germany, Italy and now the UK, there does seem to be an emerging picture of smell loss as an important marker of COVID-19 and, crucially, one that often seems to occur in advance of other symptoms and may, in some, be the only symptom. Early identification of anosmia as a potential marker of infection could help both target testing and diminish the spread of COVID-19.

References

1 https://www.entuk.org/sites/default/files/files/Loss%20of%20sense%20of%2...
2 https://www.entuk.org/sites/default/files/files/Advice%20for%20patients%...
3 https://www.kcl.ac.uk/news/loss-of-smell-and-taste-a-key-symptom-for-cov...
4 https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciaa330/581...
5 https://www.medrxiv.org/content/10.1101/2020.03.23.20041889v1.full.pdf
6 https://twitter.com/GCChemosensoryR
7 https://www.facebook.com/groups/Covid19SmellTasteLossGCCR/
8 https://www.entuk.org/sites/default/files/files/Loss%20of%20sense%20of%2...