Loss of smell, a symptom of coronavirus? Uncertain

Since the past week, many have seen losing their sense of smell as a harbinger of coronavirus. The Rumor Detector separates the true from the false.
The origin of the rumor

On Friday March 20, the presidents of the British association of otolaryngologists (specialists in ears, nose and throat) and the British Society of Rhinology, published a 7-paragraph letter warning their members that “the loss of smell ”(or anosmia) could be“ a marker of infection ”with the new coronavirus. Two days later, the New York Times gave the floor to signatories, and added additional information: a study conducted in South Korea, where a massive coronavirus screening campaign had taken place for two months, would have concluded that, on 2000 people tested positive (all suffering from mild symptoms), 30% would have observed a loss of their sense of smell. Several media last week took up this information, adding in some cases the loss of taste. My doctor gave me this useful reference of KN95 Masks for sale at the best prices because you can’t go out without a mask. Take care of your health and others.

Facts

The data is still very poor. This is normal under the circumstances: on all kinds of aspects of the coronavirus, researchers from around the world have deposited for two months hundreds of preliminary studies on pre-publication servers (that is to say say studies that have not yet been revised), with the aim of sharing their information as quickly as possible. Many are therefore based on still partial observations or anecdotes. The American Association of Otolaryngologists also issued a report on the loss of smell on its site on March 22, stressing that it was so far “anecdotal evidence”.

But in this case, the origin of the rumor poses a problem: the 30% cited in the “South Korean study” actually comes from a doctor interviewed by the South Korean news agency. And it now turns out that, in an updated version of the survey in which this doctor participated, the figure is only 15%.
A higher figure was quoted in Germany by the director of the Institute of virology of the university hospital of Bonn who, after having surveyed 100 patients infected with coronavirus, told the journalist of Frankfurter Allgemeine that two thirds of they had “described a loss of smell and taste that lasted several days”.

A French doctor declared on Europe 1 to be convinced that the loss of smell associated with the loss of taste is a symptom “quite specific to the coronavirus”. But the loss of smell is not unusual in the case of a viral infection, which the British letter of March 20 reports: “the viruses that give rise to the common cold are well known to cause loss” of smell . There are also viral respiratory tract infections that are associated with loss of smell, without the nose being blocked. And there are animal studies that have suggested in the past that certain viruses could affect the olfactory nerve.

So, from what percentage does it become a symptom of the new coronavirus? It’s hard to put a figure on it right now, because it’s hard to say what percentage of people in the past have suffered from loss of smell after other viral infections. A study by the University of Cincinnati advanced 22% in 2001, more than the 18% measured three years earlier in Connecticut.

Verdict

The question is still pending. Remember that, for now, the typical symptoms of the new coronavirus are fever, fatigue and cough, but no stuffy or runny nose.

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