Covid has been around for more than two years now. We all know that loss of smell and taste go hand in hand when someone is infected with this highly infectious virus. While a significant number of patients who tested positive with COVID-19 lost their sense of smell, researchers and scientists did not fully understand the reason behind it until recently. But a recent study, published in the journal Cell, has explained how exactly it happens.
According to the research, smell loss is mainly because of what experts refer to as ‘olfactory dysfunction’. What was shocking is that the researchers found that COVID-19 does not actually infect the nerves responsible for detecting the smell.
“SARS-CoV-2 only enters the nerve cells in exceedingly rare situations. The smell loss that is experienced acutely in COVID-19 is likely due to the loss of olfactory receptors on these nerves,” said study co-author Dr Jonathan Overdevest, MD, assistant professor of rhinology and skull base surgery at New York-Presbyterian/Columbia University Irving Medical Center.
According to Dr Sam Huh, MD, chief of otolaryngology at Mount Sinai Brooklyn Hospital, olfactory receptors typically surround and support olfactory nerves by changing scent molecules from fat-soluble to water-soluble so they can be washed away and make way for new incoming scents.
When coronavirus infects a person, it kills these support cells, leading to an inflammatory immune response in the area. However, this could be an evolutionary adaptation to prevent the virus from entering the brain.
The interruption in regularly scheduled sniffing also messes with sensations in your mouth: “We know that smell is integral to the way that we perceive the flavor of foods, at times more important than taste,” says Dr. Overdevest.
How does sense of smell and taste ultimately return?
Patients recover their sense of smell and taste after olfactory receptor cells regenerate. But the time for this recovery may vary. It may take anywhere from a few weeks to eight months.