How COVID-19 works to destroy our sense of smell

[A]nosmia [loss of sense of smell] seen with COVID-19 is present in 30–98 percent of infected people seen in hospitals, far more than occurs with other known respiratory infections.

…

How does the virus attack the sense of smell? 

…

There is evidence that the virus can migrate into the central nervous system via the nose and olfactory bulbs as well as by other routes without invading the sensory neurons. … The relatively fast recovery of olfactory function in most patients also lends support to a peripheral cause that does not kill the olfactory sensory neurons. Although these neurons do regenerate throughout life, they do not do so suddenly but rather in a process that takes 30 days or more in which sensation would gradually improve. (Some people who became anosmic as a result of the virus have not yet recovered their sense of smell. This may point to widespread death of sensory neurons or central damage in some individuals.) Because olfactory symptoms can occur very early in the disease, before respiratory symptoms, this may make understanding the virus’ entry into cells in the olfactory sensory epithelium particularly important for understanding infection.

Read the original post