Study: Loss of smell in Long COVID caused by this

By Mark Waghorn via SWNS

Loss of smell in Long COVID is caused by a strong immune response, according to new research.

Some fail to recover their olfactory senses because of an ongoing assault on nerve cells.

The discovery offers hope of better treatments. Around 1.5 Britons have been struck down.

Senior author Professor Bradley Goldstein said: "We are hopeful 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 work is already underway in his head and neck surgery lab at Duke University, Durham, North Carolina.

It could also have implications for other symptoms that might be undergoing similar inflammatory processes.

Long COVID is an umbrella term for debilitations lasting more than 12 weeks - ranging from fatigue to fever and tummy pain.

Goldstein said: "One of the first symptoms that has typically been associated with COVID-19 infection is loss of smell.

"Fortunately, many people who have an altered sense of smell during the acute phase of viral infection will recover smell within the next one to two weeks, but some do not.

"We need to better understand why this subset of people will go on to have persistent smell loss for months to years after being infected."

The US team analyzed cell samples from nose linings collected from 24 biopsies - including nine Covid patients with long-term smell loss.
 
The approach revealed widespread infiltration of immune system T-cells. They were engaged in an inflammatory response in the olfactory epithelium.

This is tissue in the nose where nerve cells that control smell are located, explained Goldstein.

This unique inflammation process persisted despite the absence of detectable levels of SARS-CoV-2 - the virus that causes COVID-19.

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

Goldstein said: "The findings are striking. 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, he said.

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

An estimated 400,000 people in the UK have been hit by Long COVID for more than a year.

Effects linger in up to a fifth of coronavirus survivors.

The study is published in the journal Science Translational Medicine.