(ORDO NEWS) — Loss of smell has been one of the main known symptoms of COVID-19 since the beginning of the pandemic. The reason underlying this mechanism was still not known.
The lack of smell is very annoying and frustrating for many COVID-19 survivors, and the road to recovery can be long.
“Fortunately, many people who have an altered sense of smell during the acute phase of a viral infection will regain their sense of smell within the next one to two weeks, but some do not,” study author Bradley Goldstein said.
“We need to better understand why this subgroup of people has sustained loss of smell for months or years after being infected with SARS-CoV2.”
The researchers found that the immune attack on the olfactory nerve cells continues, which is linked to a decrease in the number of cells. The results of the study were published in the journal Science Translational Medicine.
The researchers took samples of the olfactory epithelium (tissue in the nose where olfactory nerve cells are located), nine of which were taken from people with long-term loss of smell. Samples were subjected to single-cell RNA sequencing and immunohistochemistry.
The scientists found that nine samples with loss of smell contained fewer olfactory sensory neurons than controls. This decrease may have been caused by tissue damage from ongoing inflammation.
In addition, the results showed that there was a widespread infiltration of T cells involved in the inflammatory epithelium.
“The results are amazing,” Goldstein said. “It’s almost like an autoimmune process in the nose.
We hope that modulating the abnormal immune response or repair processes in the nose of these patients may help to at least partially restore the sense of smell.”
Despite the small sample size, the results of the study seem promising, and the mechanisms responsible for the loss of smell may also explain other long-term symptoms of COVID-19, such as brain fog, general fatigue, and shortness of breath.
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