Collecting smell and taste scores from individuals with and without a history of COVID-19, researchers found significantly lower scores for smell in COVID-19-diagnosed individuals.
Among 340 individuals with a history of COVID-19, 30.3% experienced some degree of smell dysfunction for a mean length of 1 year following their diagnosis. Researchers also found an association between age and smell/taste scores, observing that scores decreased as age increased.1
“Millions of people around the globe have suffered this symptom during the pandemic. We found that probably 80% of those patients who have a loss or distortion of their sense of smell will recover that sense about 1 to 3 months after the COVID-19 infection has resolved. But that still leaves up to 20% of people who have an ongoing disturbance in their sense of smell,” Timothy Smith, MD, MPH, FACS, ear, nose, and throat specialist at Oregon Health & Science University, told the Oregon Health News Blog.2
Compared with other studies—specifically Alkanat et al’s, which used oral/nasal corticosteroid therapy to test for smell loss3—Sharetts et al used the 53-item Waterless Empirical Taste Test (WETT) and the 40-item University of Pennsylvania Smell Identification Test (UPSIT).1
With the aim of collecting long-term smell and taste data associated with COVID-19, researchers compared the results of 340 participants with a history of COVID-19 with 434 participants without COVID-19 history. They also tested both populations with a mean of 395 days between diagnosis and testing, ranging from 363 to 425 days.1
Among the 340 individuals with a history of COVID-19, 103 (30.3%) had some degree of smell dysfunction compared with 91 (21%) in the non-COVID-19 group. With almost a third of all individuals experiencing smell dysfunction, and just a smaller number of individuals in the non-COVID-19 group, researchers deemed this a significant difference despite mean UPSIT scores of 34.39 and 35.86 for participants with a history of COVID-19 and those without, respectively.1
Almost a third of all individuals experienced smell dysfunction 1 year after COVID-19 diagnosis. | image credit: Evgenia / stock.adobe.com
Furthermore, researchers found that as participants’ age increased, both their UPSIT and WETT scores decreased. This may owe to a larger issue associating age with smell or taste loss, rather than COVID-19 diagnosis.
They also found that women had higher test scores than men, but this was also deemed insignificant to the study’s overall outcome.
However, researchers did find a significant difference between COVID-19 variants in individuals with a history of the infection’s various strains, specifically in omicron, alpha, and the original COVID-19 variants.
Compared with the omicron variant (mean UPSIT score 35.19), the original and alpha variants mean UPSIT scores were 33.11 and 32.30 respectively, indicating a significant difference between the omicron variant and both the alpha and original COVID-19 variants.1
There were no statistically significant findings between these same variants within the WETT tests in either the COVID-19-infected population or those not infected.
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“Long‐term loss of smell can result in a number of issues since the sense of smell is an essential alarm system that regulates food intake and plays a role in social relationships. The negative effects of loss of smell include decreased pleasure in eating, loss of appetite, difficulty in cooking, inability to recognize spoiled food, change in body weight,decreased safety, concerns about personal hygiene, feelings of vulnerability, moods swings and depression and a decrease in social interactions, professional success, and sexual health,” wrote Alkanat et al.3
Of the 60% of Americans who have been diagnosed with COVID-19, 3 out of 10 reported symptoms of long COVID.4 The symptoms of Long COVID, also referred to as post COVID-19 condition (PCC), can include, among other symptoms, an acute loss of smell and/or taste—which is exactly what researchers found in the Sharetts et al study.1
With a loss of smell and taste reported as one of the most prominent PCC complications, the researchers we’re able to confirm the persistence of smell loss specifically in PCC patients.
“In this nationwide cross-sectional study of participants with and without a history of COVID-19, empirically measured taste function was normal 1 year after exposure to COVID-19. However, smell loss remained in nearly one-third of individuals with exposure, likely explaining taste complaints of many individuals with PCC,” concluded the authors.1
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