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COVID-19’s Effect on Taste, Smell Improves in a Month for Most Patients

For most patients with COVID-19, the loss of taste and smell is limited and either improves or disappears after four weeks. That’s the result of a study looking at a group of patients with the troubling symptoms. Find out why researcher think that loss of taste and smell occurs, usually in milder cases.

TREVISO, ITALY – Here is some comforting news pharmacists can share with COVID-19 patients who have suffer from an altered sense of smell or taste. The symptom appears to improve or resolve in nearly patients by four weeks from onset.

That’s according to a report in JAMA Otolaryngology – Head & Neck Surgery. Researchers from University of Padova in Treviso, Italy, Guy’s and St Thomas’ Hospitals in London and colleagues sought to determine the evolution of sudden-onset altered sense of smell or taste in patients with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

To find out, they conducted a prospective survey-based study of 202 patients, explaining, “The loss of smell or taste is among the most common and persistent symptoms of mildly symptomatic patients with coronavirus disease 2019; however, most patients reported a complete resolution or improvement of these symptoms.

Participants were mildly symptomatic adults who were consecutively assessed at Treviso Regional Hospital, Italy, between March 19 and March 22, 2020l. All tested positive for SARS-CoV-2 RNA by polymerase chain reaction on nasopharyngeal and throat swabs.

 Of 202 patients completing the survey at baseline, 187 (92.6%) also completed the follow-up survey. Most of those were women, 55.1%, with a median age of 56.

Researchers report that the evaluation of the evolution of altered sense of smell or taste in the 113 patients reporting sudden onset of these symptoms at baseline showed that 55 patients (48.7%; 95% CI, 39.2-58.3) reported complete resolution of smell or taste impairment, 46 (40.7%; 95% CI, 31.6-50.4) reported an improvement in the severity, and only 12 (10.6%; 95% CI, 5.6-17.8) reported the symptom was unchanged or worse. The authors add that persistent loss of smell or taste was not associated with persistent SARS-CoV-2 infection.

According to the study, human strains of coronavirus have been shown to invade the central nervous system through the olfactory neuroepithelium and propagate from within the olfactory bulb. In addition, researchers point out, nasal epithelial cells have the highest expression of the SARS-CoV-2 receptor, angiotensin converting enzyme 2, in the respiratory tree.

“Smell impairment was first observed among other neurologic manifestations of COVID-19 in hospitalized patients, and subsequently has been reported to be a common symptom reported in patients with mild disease,” the authors advise.

Recently, the same researchers reported the prevalence of altered smell or taste to be 64% among a case series of 202 mildly symptomatic home-isolated patients with confirmed SARS-CoV-2 infection. The follow-up study was to evaluate the evolution of altered sense of smell or taste and other COVID-19 associated symptoms in that case series.