In an effort to better understand why this particular symptom is so common among COVID-19 patients, an international team of researchers led by neuroscientists at Harvard Medical School (HMS) was able to identify the olfactory cell types in the upper nasal cavity most vulnerable to infection by SARS-CoV-2, the virus that causes COVID-19.
In a surprise to researchers, sensory neurons that detect and transmit the sense of smell to the brain were not included to be among the vulnerable cell types.
“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,” senior study author Sandeep Robert Datta, an associate professor of neurobiology in the Blavatnik Institute at HMS, said in a news release.
The study’s findings were recently published in Science Advances.
The researchers, however, noted that a COVID-19 infection likely won’t cause lasting damage and persistent loss of smell.
“I think it’s good news because once the infection clears, olfactory neurons don’t appear to need to be replaced or rebuilt from scratch,” Datta said.
“But we need more data and a better understanding of the underlying mechanisms to confirm this conclusion.”
Scientists have discovered that a majority of COVID-19 patients experience some form of anosmia—most often temporary.
Health records have indicated that COVID-19 patients are twenty-seven times more likely to have loss of smell but are only about 2.2 to 2.6 times more likely to have fever, cough or respiratory difficulty, compared to individuals who don’t have COVID-19.
The study’s results can now be used to help accelerate efforts to find better treatments for anosmia.
“Anosmia seems like a curious phenomenon, but it can be devastating for the small fraction of people in whom it’s persistent,” Datta said.
“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.”
Ethen Kim Lieser is a Minneapolis-based Science and Tech Editor.