COVID-19 School of Medicine

COVID Survivors Hope Experimental Therapy Will Help Them Learn To Smell Again

Elizabeth Tesson remembers the exact moment she lost her sense of smell, the day after she tested positive for COVID-19.

“I got a very odd feeling in my nose, like a burning sensation in my sinuses and along my cheeks,” said Tesson, who lives in St. Louis County. “About an hour and a half later, I went to take a shower, and I couldn’t smell the soap.”

That was almost five months ago — and her sense of smell still hasn’t returned.

Loss of smell, or anosmia, is one of the telltale signs of COVID-19, affecting up to 80% of patients by some estimates. Nearly a year into the pandemic, scientists are scrambling to understand how the coronavirus damages the sensory system and if there’s a way to reverse it. Though there is no cure, an experimental therapy currently being tested at Washington University has given some patients hope.

How exactly the virus causes smell loss is still somewhat of a mystery. Most people recover their sense of smell within weeks, but some, like Tesson, are still unable to smell months later.

At first, scientists thought the virus might be attacking neurons inside the nose responsible for detecting and transmitting smells to the brain. Instead, the virus appears to primarily affect cells surrounding the nerve that are able to regenerate more quickly, perhaps explaining why most patients recover their sense of smell.

But given the sheer number of COVID-19 cases nationwide, Jay Piccirillo, MD, a Washington University professor of otolaryngology, worries about a “coming tidal wave” of long-term smell loss.

About 1 in 10 people will experience persistent disruptions in smell six months after recovering from COVID-19, Piccirillo said, generating “a number of people with anosmia that we’ve never really experienced.”

Though Piccirillo has studied viral-related smell loss for years, his research team has struggled to recruit enough patients — and those who signed up were often unsure when they had lost their sense of smell. “All of that faded away with this COVID pandemic,” he said. “For once in my professional lifetime, people knew exactly when they lost their sense of smell, and we had a large number of patients.”

His research team is among the first in the country to test whether an existing therapy known as “smell training” may help COVID-19 patients regain the ability to smell. As part of the 12-week study, patients sniff certain essential oils, like peppermint and lemon, twice a day, sometimes while looking at photos associated with the smells.

Research results from studies going back more than a decade have been promising, with patients showing improved olfactory function and even changes in brain structure after completing the training.

The Wash U research team plans to mail about 250 smell training kits to patients nationwide who have recovered from COVID-19 but have not regained their sense of smell or taste.

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