From the first reports coming out of Wuhan, Iran and later Italy, we knew that losing your sense of smell (anosmia) was a significant symptom of the disease. Now, after months of reports, both anecdotal and more rigorous clinical findings, we think we have a model for how this virus may cause smell loss.
One of the most common causes of smell loss is a viral infection, such as the common cold, sinus or other upper respiratory tract infections. Those coronaviruses that don’t cause deadly diseases, such as COVID-19, Sars and Mers, are one of the causes of the common cold and have been known to cause smell loss. In most of these cases, sense of smell returns when symptoms clear, as smell loss is simply the result of a blocked nose, which prevents aroma molecules reaching olfactory receptors in the nose. In some cases, smell loss can persist for months and years.