Olfactory, gustatory disorders persist after COVID-19

Olfactory and gustatory dysfunctions, even when assessed through validated psychophysical tests, are common chronic symptoms after the coronavirus disease 2019 (COVID-19), a recent study has found.

“Olfactory and gustatory disorders are prominent symptoms of acute COVID-19. Although both senses recover in many patients within weeks to months, persistency has been described in up to 60 percent,” the researchers said. “However, up to now, most reports on the course of chemosensitive disorders after COVID-19 are not based on psychophysical testing but only on subjective patients’ ratings.”

The study subjected 303 patients (mean age 49.0 years, 55 percent women) to psychophysical testing, involving validated and blinded pocket smell tests and taste strips. All patients had tested positive for COVID-19 8 months before enrolment.

Subjectively, 70 percent and 74 percent of patients said that they suffered olfactory and gustatory impairments, respectively, during the acute phase of COVID-19. Eight months later, these percentages dropped to 28 percent and 24 percent, respectively. Visual analogue scale scores revealed current self-rated olfactory and gustatory function scores of 7.9 and 8.2, respectively.

The pocket smell test had a mean score of 6.4 and found that 18 percent (n=54) of patients were hyposmic. Majority (82 percent; n=249) had normal smell function.

A similar pattern was reported for the taste strip tests, which returned a mean score of 9.7. A much greater proportion (32 percent; n=97) had dysgeusia, though majority (68 percent; n=206) still showed normal gustatory function.