Coronavirus: scientists uncover why some people lose their sense of smell

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.