What’s the story with anosmia and COVID-19?

Sudden loss of smell could be a sign of COVID-19, say ENT specialists from around the world, even in the absence of other symptoms.

The experts from the UK, the US and Australia are calling for anosmia to be added to the list of possible symptoms to be asked about when screening for potentially having the virus.

It is believed this novel coronavirus causes swelling of the olfactory mucosa more than other viruses, suggesting the symptom could be used as a clinical indicator of COVID-19.

According to a letter from ENT UK to Public Health UK,1 there is increasing evidence that the symptom frequently occurs among patients who are manifestly unwell with the virus, but disturbingly, it also appears to sometimes occur as the only significant symptom of the disease.

“In Germany it has been reported that more than two in three cases have anosmia. In South Korea where testing has been more widespread, 30% of patients testing positive have had anosmia as their major symptom in otherwise mild cases,” say the letter authors, Professor Claire Hopkins, President of the British Rhinological Society and Professor Nirmal Kumar, President of ENT UK.

But they note the real danger lies with the patients in whom a sudden loss of smell is their only symptom of the disease.

“Iran has reported a sudden increase in cases of isolated anosmia, and many colleagues from the US, France and Northern Italy have the same experience,” the UK experts said.

Here in Australia, our own experts are expressing similar concerns about these cases of anosmia-only affected patients.

“It is these ‘silent carriers’ who may remain undetected by current screening procedures, which may explain why the disease has progressed so rapidly in so many countries around the world,” says South Australian specialist Flinders University Professor Simon Carney, from the Southern ENT and Adelaide Sinus Centre.2

He suggests early identification of these carriers could help slow the spread of the infection. All these experts, along with the American Academy of Otolaryngology3 suggest anosmia – and the associated dysgeusia (distortion in the sense of taste) be added to the list of screening items for potential COVID-19.

There is an issue, of course, with the fact that anosmia, especially as an isolated symptom does not see the patient being eligible for COVID-19 testing here in Australia. Or in the UK apparently.

However, while we await more evidence on the issue, ENT UK is advising that any patient presenting with sudden anosmia as their only symptoms be asked to self-isolate (they suggest for seven days, whereas here in Australia our self-isolation time is generally two weeks) in an attempt to reduce the community spread of this disease.

Interestingly, they also recommend against using oral steroids as a possible treatment for anosmia as it has been shown that corticosteroid use can increase the severity of COVID-19 disease. The presence of nasal polyps is a possible exception to this rule.

  1. Hopkins C, Kumar N. Loss of sense of smell as marker of COVID-19 infection. Available from: https://www.entuk.org/sites/default/files/files/Loss%20of%20sense%20of%20smell%20as%20marker%20of%20COVID.pdf
  2. Flinders University [Internet]. Adelaide, SA. Flinders University Newsdesk. Loss of smell ‘first sign’ of COVID-19. 2020 Mar 24; [about 3 screens]. Available from: https://news.flinders.edu.au/blog/2020/03/24/loss-of-smell-first-sign-of-covid-19/
  3. American Academy of Otolaryngology [Internet]. Alexandria, US-VA. American Academy of Otolaryngology. Coronavirus Disease 2019: Resources. Last reviewed 2020 Mar 31; [about 8 screens]. Available from: https://www.entnet.org/content/coronavirus-disease-2019-resources
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