How COVID-19 Causes Loss of Smell. Reedus

An international group of scientists from Harvard Medical School published a study in which experts suggested why the loss of smell occurs with coronavirus.

Temporary loss of smell, or anosmia, is a major neurological symptom and one of the earliest and most frequent symptoms of COVID-19. Studies believe this feature is a better indicator of illness than fever.

In a recent study, scientists have identified the types of olfactory cells most vulnerable to SARS-CoV-2 infection. Surprisingly, the sensory neurons that detect and transmit the sense of smell to the brain are not vulnerable cell types.

They also found that olfactory sensory neurons do not express the gene encoding the ACE2 receptor protein, which SARS-CoV-2 uses to penetrate in human cells, but the receptor is expressed in cells that are closely associated with olfactory neurons.

The findings suggest that infection of neural cell types may be responsible for anosmia in COVID-19 patients.

Our research shows that coronavirus alters patients’ sense of smell not by directly infecting neurons, but by affecting the function of supporting cells. This means that in most cases, SARS-CoV-2 infection is unlikely to permanently damage the olfactory nerve circuits and lead to persistent anosmia. — say scientists.

Previous research has shown that most COVID-19 patients lose their sense of smell for a couple of weeks, after which the ability to distinguish between taste and smell gradually returns.

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