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  • A new study finds that damage to nasal tissue may be the reason some people lose their sense of smell after having COVID-19.
  • Experts say this is actually a good sign because tissue may recover more quickly than nerves.
  • Smell training is one way people may be able to recover their sense of smell.

One distinctive symptom of COVID-19 remains the loss of sense of smell and taste that can affect people for weeks or months after developing the disease.

The decreased or altered sense of smell, called olfactory dysfunction, was originally thought to be due to damage of the olfactory nerves. But new research published this week in The Laryngoscope finds that loss of smell due to COVID-19 may also be because of swelling and blockage of the nasal passages.

“Initially, we noticed a pattern in patients with COVID-19 that they lost their sense of smell and taste. We noticed these findings could be used as an indicator of whether or not a patient had COVID-19, but we thought it had to do with the olfactory nerve,” said Dr. Anjali Bharati, an ER physician at Lenox Health Greenwich Village in New York, NY.

Originally the loss of taste and smell due to COVID-19 was thought to be damage to the olfactory nerve. While evidence was limited for a direct relation between SARS-CoV-2 and abnormal brain findings, the theory was that the olfactory dysfunction was due to the olfactory nerve.

This raised further questions on whether or not the nerve damage would be temporary or if the patient would be able to recover.

However, this new research offers a different perspective and perhaps some optimism. Researchers combed through medical reports that detailed changes in olfactory structures through imaging tests of patients with COVID-19.

They found a prevalence of an olfactory cleft abnormality. The olfactory cleft is the channel through which airborne molecules reach the olfactory neurons, which connect to the brain in order to determine smells. In patients with COVID-19 and olfactory dysfunction, the cleft abnormality was 16 times higher.

This means that a contributing factor of the loss of smell and taste is due to the tissues instead of nerves.

The good news is that cells turn over and heal much more easily than nerve damage.

“Nerve damage is a more serious thing. The question becomes ‘does it recover?’” said Bharati. “This news involves the physical makeup of the nose, like the nasal passage and the back of the throat. Nerve damage is part of the brain, which is more disconcerting than the nasal passages.”

Not everyone will experience the loss of smell and taste if they develop COVID-19. But this research means that experts understand much more about why this happens.

And this news does present an optimistic view that the symptoms may be temporary for many or most people.

“It’s an important finding,” said Bharati. It may mean that the symptoms are reversible as time goes on and cells turn over. It’s not permanent.”

Kai Zhao, PhD, associate professor, otolaryngology, The Ohio State University College of Medicine, said recovery times vary widely from one to three weeks to months or years.

“While there are limited treatment options, people have been using smell training as a treatment option with mixed outcomes,” Zhao said.

Smell training involves smelling items like specific scents of items like oranges or coffee grounds.

Zhao suggested that vaccination may alleviate symptoms but clarified that there is no definitive proof of that yet.

However, it is important to note that the findings may not fully account for people living with the extended loss of sense of smell or taste. More research will have to be conducted.

Zhao also noted that some of the imaging was with MRI, while others used CT, and that the time frame of the studies was not controlled.

But the experts say findings are interesting and open the door for more research regarding the blockage of nasal passages and COVID-19.