Covid19 and the Human Brain

One reliable symptom of an infection with Sars-CoV-2, is a loss of the sense of smell. This has worried scientists, because of the short distance from the olfactory mucosa to the brain's olfactory bulb. The olfactory mucosa 'captures' molecules but their smell (dependent on molecular shape) is processed in the olfactory bulb. A study in the journal Cell suggests, however, that the virus does not infect the olfactory sensory neurons in the mucosa (https://www.theguardian.com/world/2021/nov/03/covid-19-virus-does-not-infect-human-brain-cells-new-study-suggests ). The impairment of the sense of smell seems to be produced by the virus attacking sustentacular cells that are also in the olfactory mucosa. Sustentacular cells support and nourish the olfactory sensory neurons but are not neural cells per se. It seems likely that Sars-CoV-2 will not spread, from the olfactory bulb into the rest of the brain. This finding also indicates that the loss of the sense of smell is likely to be a short-lasting phenomenon.