20th March 2020
Post-viral anosmia is one of the leading causes of loss of sense of smell in adults, accounting for up to 40% cases of anosmia. Viruses that give rise to the common cold are well known to cause post-infectious loss, and over 200 different viruses are known to cause upper respiratory tract infections. Previously described coronaviruses are thought to account for 10-15% cases. It is therefore perhaps no surprise that the novel COVID-19 virus would also cause anosmia in infected patients.
There is already good evidence from South Korea, China and Italy that significant numbers of patients with proven COVID-19 infection have developed anosmia/hyposmia. In Germany it is reported that more than 2 in 3 confirmed cases have anosmia. In South Korea, where testing has been more widespread, 30% of patients testing positive have had anosmia as their major presenting symptom in otherwise mild cases.
In addition, there have been a rapidly growing number of reports of a significant increase in the number of patients presenting with anosmia in the absence of other symptoms – this has been widely shared on medical discussion boards by surgeons from all regions managing a high incidence of cases. 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. I have personally seen four patients this week, all under 40, and otherwise asymptomatic except for the recent onset of anosmia – I usually see roughly no more than one a month. I think these patients may be some of the hitherto hidden carriers that have facilitated the rapid spread of COVID-19. Unfortunately, these patients do not meet current criteria for testing or self-isolation.
While there is a chance the apparent increase in incidence could merely reflect the attention COVID-19 has attracted in the media, and that such cases may be caused by typical rhinovirus and coronavirus strains, it could potentially be used as a screening tool to help identify otherwise asymptomatic patients, who could then be better instructed on self-isolation.
Given the potential for COVID-19 to present with anosmia, and the reports that corticosteroid use may increase the severity of infection, we would advise against use of oral steroids in the treatment of new onset anosmia during the pandemic, particularly if it is unrelated to head trauma or nasal pathology (such as nasal polyps).
There is potential that if any adult with anosmia but no other symptoms was asked to self-isolate for seven days, in addition to the current symptom criteria used to trigger quarantine, we might be able to reduce the number of otherwise asymptomatic individuals who continue to act as vectors, not realising the need to self-isolate.
Prof Claire Hopkins, BMBCh, MA FRCS(ORLHNS) DM(Oxon)
President of the British Rhinological Society
Professor of Rhinology, King’s College London
Consultant ENT Surgeon, Guy’s and St Thomas’ Hospitals
Prof Nirmal Kumar,
President of ENT UK
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AbScent has a fully interactive website, with links to the membership area, Snif Smell Training app and a selection of downloadable resources about smell training in English, Spanish, French, and Portuguese. Other language versions of these materials, including Italian, will be available soon.
AbScent is a UK charity that supports people all over the world who are experiencing some form of smell dysfunction. Chrissi Kelly, founder of AbScent is available for interviews to talk about the impact of smell loss, smell training and other support that is available.
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Notes to editors:
AbScent is a UK registered charity No. 1183468 started in 2018 to help people who are experiencing the distressing effects of smell loss.
For more information on the latest available research into smell loss visit: https://abscent.org/learn-us/latest-research
AbScent’s vision is a world where smell loss is recognised by the general population as a challenging condition, where patients are fully supported by the medical community and their care circles, and where healing strategies are explored, funded and made available to the world-wide population.
The effects of smell loss can be complex and therefore support is necessary from several areas to suit the biopsychosocial needs of the community.
Smell training is a supportive technique for people who have suffered smell loss and has been demonstrated in over a dozen scientific studies to be of benefit for people who have lost their sense of smell after a virus or injury.
Smell training is not a cure, but a way of amplifying natural recovery. Every time it is done it stimulates the olfactory nerves and this encourages the nerve to regenerate. It can be likened to physiotherapy for the nose.