The research, which was published in JAMA Otolaryngology-Head & Neck Surgery, analyzed data from daily new cases of COVID-19 from The COVID Tracking Project.
Researchers estimated that up to 1.6 million people who have had COVID-19 are struggling with this symptom.
The researchers analyzed positive COVID cases in the U.S. between January 13, 2020, and March 7, 2021. They also incorporated recent data that found 52.7% of people with COVID-19 had olfactory dysfunction (a reduced or distorted ability to smell) and 95.3% recovered.
Based on estimates, the researchers found that the number of Americans expected to develop loss of smell by August 2021 was 712,268. The highest estimate, they found, is 1,600,241.
“This analysis of new daily cases of COVID-19, the acute incidence of olfactory dysfunction, and rates of recovery suggest that more than 700,000, and possibly as many as 1.6 million, U.S. individuals experience chronic olfactory dysfunction because of SARS-CoV-2,” the researchers wrote. “To put this number in context, before the COVID-19 pandemic, the National Institute on Deafness and Other Communication Disorders estimated that, among U.S. adults 40 years or older, measurable olfactory dysfunction was found in up to 13.3 million adults.”
The addition of 700,000 to 1.6 million new cases of chronic olfactory dysfunction represents a 5.3% to 12% increase in national cases, they point out.
Why COVID-19 Can Cause Loss of Smell
It’s not entirely clear why this symptom can happen with COVID-19.
However, it’s most likely caused by damage to the cells that support and assist the olfactory neurons, called sustentacular cells. These cells can regenerate, which can help explain why most people regain their sense of smell quickly.
Richard Watkins, MD, an infectious disease physician and professor of internal medicine at the Northeast Ohio Medical University, told Verywell that the findings “demonstrate there can be long-term effects following infection with COVID… [That] is different than most other viral illnesses that humans acquire, like influenza. There is still a lot about COVID that we don’t understand.”
The Impact of Losing a Sense of Smell
“Everyone has been looking at COVID in terms of whether you live or die, and there’s a lot more to it than that,” Thomas Russo, MD, professor and chief of infectious disease at the University at Buffalo in New York, told Verywell. “Individuals that have symptoms post-COVID can have them dramatically impact their lifestyle and activities of daily living.”
Losing your sense of smell means “losing one of the pleasures in life," Russo said. “It’s extremely disconcerting for people. And, for people who rely on their sense of taste and smell for work, it can impact job performance and even cause some people to need to have a career change.”
“It’s one more example of how we need to look at the big picture of COVID,” Russo added.
Experts stress the importance of getting vaccinated against COVID-19. “If you don’t get infected in the first place, you won’t lose your sense of taste or smell,” Watkins said.
Russo agreed. “You won’t suffer this consequence if you don’t get infected,” he said.
There is a chance of getting a breakthrough infection, even if you’re fully vaccinated, Russo noted. But, he added, “symptoms last for a shorter period of time and are milder.”
How long this symptom lasts depends on the individual. “Most people, but not everyone, gets everything back within a year,” Russo said. “We have to continue to follow this to see if it’s permanent or not.”
The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.
