As we all know, one of the most common symptoms of mild COVID-19 is the loss of smell and taste. Unexpectedly, as per a recent study, the infection by the novel COVID-19 can damage important cells that support the nerve cells responsible for relaying scent to the brain.
The partial or full loss of smell, also known as anosmia, is caused not only by Coronavirus but by other respiratory infections as well. However, anosmia is more accurate predictor of COVID-19 than other symptoms like fever or dry cough.
According to the study, published in Science Advances over the weekend, researchers looked at the cells that line our nasal cavity, including those in olfactory nerve. For the unversed, the olfactory nerve receives information about odors from the outside world via receptors, which actually react to the various chemical compounds we know as scents. They eventually send information to the brain, where perceived as of smell.
The researchers found that in the tissue area where the olfactory nerve is located, cells expressed two proteins key to the coronavirus, ACE2 and TMPRSS2. The novel COVID-19 targets the receptors for these proteins as a way to enter and infect new cells. Also, surprisingly, as per other experiments, it wasn’t the nerve cells that were expressing ACE2. It was indeed their supporting cast that was doing so. “Our findings indicate that the novel coronavirus changes the sense of smell in patients not by directly infecting neurons but by affecting the function of supporting cells,” said senior study author Sandeep Robert Datta, a neurobiologist at Harvard Medical School, as per an official statement.
Well, that comes a surprise, and ideally, it can be beneficial for COVID-19 survivors as indirect damage to our sniffing process should less likely lead to a long-term loss of smell. Also, it means that the brain is rarely attacked directly by the coronavirus. Albeit, it is still to be known if our olfactory nerve can or can’t be permanently harmed by COVID-19.
Meanwhile, the authors have noted that a lot of survivors potentially are at risk of a truly tragic deficit. And a third to two-thirds of people with COVID-19 symptoms experience anosmia. “Anosmia seems like a curious phenomenon, but it can be devastating for the small fraction of people in whom it’s persistent,” Sandeep said, adding, “It can have serious psychological consequences and could be a major public health problem if we have a growing population with permanent loss of smell.”
The novel Coronavirus has infected more than 15 lakh in India alone.