More than 1.5 million people may have chronic, COVID-related olfactory (sense of smell) dysfunction lasting six months or longer, a study has found. The figures are based on new daily cases, acute olfactory problems, and rates of recovery.

Acute olfactory dysfunction appears more often in mild COVID-19 infections than in moderate to critical COVID illness. Approximately 95% of patients recover their sense of smell at six months post-infection, but the 5% who don’t comprise a sizable number of people. 

What They Did

For the study, which was published in JAMA Otolaryngology-Head & Neck Surgery, researchers estimated the number of daily new cases of COVID-19 using national data from January 13, 2020 through March 7, 2021, from the COVID Tracking Project. 

They also incorporated the incidence of acute COVID-19 olfactory dysfunction (52.7%) based on a recent meta-analysis, and a 95.3% recovery rate from olfactory dysfunction based on another study. Lastly, the researchers created three different estimates of the cumulative frequency of COVID-19 chronic (long-term or recurring) olfactory dysfunction.

What They Found

Their calculations estimated the number of people in the U.S. who were expected to develop chronic olfactory dysfunction by August 2021:

• 170,238 people (lowest estimate)
• 712,268 people (intermediate estimate)
• 1,600,241 people (highest estimate)

According to Jay Piccirillo, M.D. of Washington University School of Medicine in St. Louis, the lead author of the study, “The addition of 0.7 to 1.6 million new cases of chronic olfactory dysfunction represents a 5.3% to 12% relative increase.” 

Prior to the COVID-19 pandemic, the authors wrote, “among U.S. adults 40 years or older, measurable olfactory dysfunction was found in up to 13.3 million adults.” 

What It Means

Picarillo and his colleagues note that “COVID-19 affects a younger demographic group than other causes of olfactory dysfunction. Thus, the lifelong burden of olfactory dysfunction will be much greater for the COVID-19 cohort than for patients in the older age groups.”

Some patients have benefited from olfactory training paired with visual stimulation. According to Jerome Lechien, M.D, Ph.D., of Paris Saclay University (who was not involved in this particular study), “It’s important to adhere to a good olfactory training program over the weeks following the persistence of loss of smell.”

Though the study has several limitations, including the likelihood of under-reported positive cases, “these data,” they wrote, “suggest an emerging public health concern of olfactory dysfunction and the urgent need for research that focuses on treating COVID-19 chronic olfactory dysfunction.”

*George, J. (2021, Nov. 18). Chronic Olfactory Loss Plagues Many with COVID-19. MedPage Today.   https://www.medpagetoday.com/infectiousdisease/covid19/95750 

Much about the novel coronavirus, i.e., COVID-19, is still not fully understood. As research progresses and our knowledge of the virus increases, information can change rapidly. We strive to update all of our articles as quickly as possible, but there may occasionally be some lag between scientific developments and our revisions.