Scientists find the cause of smell loss in long COVID

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In a study from Duke Health and elsewhere, scientists found the reason some people fail to recover their sense of smell after COVID-19 is linked to an ongoing immune assault on olfactory nerve cells and an associated decline in the number of those cells.

The finding provides an important insight into a vexing problem that has plagued millions who have not fully recovered their sense of smell after COVID-19.

While focusing on the loss of smell, the finding also sheds light on the possible underlying causes of other long COVID-19 symptoms—including generalized fatigue, shortness of breath, and brain fog—that might be triggered by similar biological mechanisms.

In the study, the team analyzed olfactory epithelial samples collected from 24 biopsies, including nine patients suffering from long-term smell loss following COVID-19.

This biopsy-based approach showed widespread infiltration of T-cells engaged in an inflammatory response in the olfactory epithelium, the tissue in the nose where smell nerve cells are located.

This unique inflammation process persisted despite the absence of detectable SARS-CoV-2 levels.

Additionally, the number of olfactory sensory neurons was diminished, possibly due to damage to the delicate tissue from the ongoing inflammation.

The team says it’s almost resembling a sort of autoimmune-like process in the nose.

Learning what sites are damaged and what cell types are involved is a key step toward beginning to design treatments.

The researchers were encouraged that neurons appeared to maintain some ability to repair even after the long-term immune onslaught.

They are hopeful that modulating the abnormal immune response or repair processes within the nose of these patients could help to at least partially restore a sense of smell.

The findings from this study could also inform additional research into other long-COVID-19 symptoms that might be undergoing similar inflammatory processes.

If you care about COVID, please read studies about a universal antibody therapy to fight all COVID-19 variants, and vaccines may increase heart disease risk.

For more information about COVID, please see recent studies about fasting method linked to less severe COVID-19, and results showing the biggest risk factors for COVID-19 death.

The study was conducted by Bradley Goldstein et al and published in the journal Science Translational Medicine.

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