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MANEND NEWS, A loss of smell has become a hallmark symptom of some COVID-19 cases. Now experts are learning how this symptom may reveal whether a person is likely to have a severe case.
About 86 percent of people who have COVID-19 lose some or all of their ability to smell. But the majority who lost their sense of smell (almost 55 percent) had a mild form of the disease, according to new research published this week.
Researchers say the reason for this isn’t well understood. But they think that patients with mild illness may have higher levels of certain antibodies that limit COVID-19 from spreading to the nose.
However, a definitive answer remains elusive, Dr. Jonathan Overdevest, assistant professor of rhinology and skull base surgery at Columbia University, told Healthline.
“We know that smell loss in COVID-19 is more than the simple mechanism we see with seasonal upper respiratory infections, where common symptoms of nasal congestion and runny nose result in poor airflow and reduced delivery of odors to the region of the nose responsible for smell,” he said.
The study analyzed patient-reported data from 2,581 individuals across 18 European hospitals.
Researchers found almost 55 percent of patients with a mild form of COVID-19 experienced some degree of smell loss (anosmia). The loss of smell lasted about 22 days.
This is compared to roughly 37 percent of moderate-to-critical cases of the disease. And patients who survived severe-to-critical COVID-19 reported loss of smell the least, at only 6.9 percent.
Asked why loss of smell might be more common in mild rather than severe cases of COVID-19, Overdevest said the large number of mild cases might have something to do with it.
“Clarity on this association is limited by a number of confounding factors. However, a major limitation to drawing this conclusion is one of bias and statistics,” he said. “Where the sheer number of milder COVID-19 cases compared to severe cases provides a broader population of individuals to have experienced smell alteration.”
Nearly 25 percent of affected people said they didn’t recover the sense of smell even 60 days after losing it.
“According to the study, the majority of people recover their sense of smell within 3 weeks,” said Dr. Robert Glatter, an emergency physician at Lenox Hill Hospital in New York. “But it may take up to 2 months in 15 percent of patients or up to 6 months in just under 5 percent of patients.”
Glatter emphasized that in the majority of patients so far, it doesn’t appear to be a permanent loss. However, he cautioned that “we still need to closely monitor patients who continue to have loss of smell.”
According to Glatter, other respiratory viruses such as cold viruses (rhinoviruses) or other common coronaviruses can lead to temporary loss of smell and taste for up to a week.
“People typically recover quickly with no long-term impairment of senses of taste or smell,” he said, and explained that it’s typically related to simple nasal congestion or swelling of nasal passages, “as opposed to injury to supporting cells for critical nerve cells seen in people diagnosed with COVID-19.”