Smell Dysfunction Common 1 After COVID-19, May Reflect Perceived Taste Loss

No difference in taste dysfunction was found between patients who developed COVID-19 and those with no history of infection at 1 year following exposure, whereas smell dysfunction was found to be more common among those with prior infection. These study results were published in JAMA Network Open.

Researchers conducted a nationwide cross-sectional study between February 2020 and August 2023 to evaluate the association between COVID-19 and long-term outcomes in taste and smell function. Patients (N=774) with and without a history of COVID-19 infection were eligible for the analysis and enrolled via social media channels and bulletin board advertisements. The primary outcomes included smell and taste function 1 year following COVID-19 exposure, which were measured using the 53-item Waterless Empirical Taste Test (WETT) and the 40-item University of Pennsylvania Smell Identification Test (UPSIT), respectively. Analysis of covariance, chi-squared, and Fisher exact probability testing were used to assess the relationship between COVID-19 and taste and smell outcomes.

The final analysis comprised 340 patients with and 434 without a history of COVID-19 infection, of whom the mean (SD) ages were 39.04 (14.35) and 39.99 (15.61) years, 62.4% and 64.5% were women, and 58.2% and 63.1% were White, respectively.

Total age- and sex-adjusted mean WETT scores were within normal ranges and did not significantly differ between patients with (33.41; 95% CI, 32.37-34.45) vs without (33.46; 95% CI, 32.54-34.38) a history of COVID-19 infection (P =.94).

In contrast, age- and sex-adjusted mean UPSIT scores were significantly lower among patients with (34.39; 95% CI, 33.86-34.92) vs without (35.86, 95% CI, 35.39-36.33) a history of COVID-19 infection (P <.001). Overall, patients who developed COVID-19 infection were significantly more likely to experience some degree of smell dysfunction (odds ratio [OR], 1.64; 95% CI, 1.18-2.27; P <.001) as well as anosmia or severe microsmia (OR, 3.28; 95% CI, 1.65-6.43; P <.001).

Further analysis among patients with a history of COVID-19 infection showed that taste outcomes did not significantly differ by causative SARS-CoV-2 variant (original untyped, Alpha, Delta, and Omicron). However, the researchers observed significantly higher rates of total and severe smell loss in patients with prior Alpha or original variant infection compared with those with no history of infection (23.8% and 13.5% vs 2.8%, respectively; P <.001).

Study limitations include the lack multiple testing periods and potentially inaccurate SARS-CoV-2 variant inference due to insufficient access to polymerase chain reaction data.

“These findings suggest that long-term taste loss perceived by many patients with COVID-19 likely reflects the loss of flavor sensations from odorant molecules reaching a damaged olfactory epithelium via the nasopharynx rather than the taste buds,” the researchers concluded.

Disclosure: This research was supported by Sensonics International, and one study author declared affiliations with biotech, pharmaceutical, and/or device companies.

This article originally appeared on Infectious Disease Advisor