Loss of Taste, Smell Could Be Early Indication of COVID-19 Infection

Pharmacists are fielding a lot of questions about symptoms that might or might not suggest COVID-19. A new study provides more information about a surprising one: Loss of taste and smell even when no other symptoms are present. Find out why those patients probably should be evaluated for novel coronavirus infection.

TREVISO, ITALY – Here’s why recommending evaluation for COVID-19 might be the best response if pharmacists get questions from anyone saying they have lost their senses of taste or smell.

Alterations in smell or taste have been frequently reported by mildly symptomatic patients with SARS-CoV-2 infection and often were the first apparent symptom, according to a research letter in JAMA.

The University of Padova-led authors point out that the main symptoms of the novel coronavirus generally are considered fever, fatigue, dry cough, myalgia, and dyspnea. Yet, they add, “Previous strains of coronavirus have been demonstrated to invade the central nervous system through the olfactory neuroepithelium and propagate from within the olfactory bulb. Furthermore, nasal epithelial cells display the highest expression of the SARS-CoV-2 receptor, angiotensin-converting enzyme 2, in the respiratory tree.”3

Researchers say that might explain anecdotal reports of anosmia, although they say they could find only one that evaluated the prevalence of smell and taste disturbance in hospitalized patients with COVID-19, reporting an overall prevalence of 34%. It didn’t include timing of onset in relation to other symptoms, however.

In light of that, the study team sought to evaluate prevalence, intensity, and timing of an altered sense of smell or taste in patients with SARS-CoV-2 infections.

Adults patients at Treviso Regional Hospital in Italy were consecutively assessed between March 19 and March 22, 2020, and were included in the study if they were positive for SARS-CoV-2 RNA based on accepted tests and also if they were mildly symptomatic and could recover at home.

Five to six days after the swap, patients were contacted by telephone to gather the demographic information and to assess them with the Acute Respiratory Tract Infection Questionnaire (ARTIQ); which scores symptoms as none, 0; a little, 1; a lot, 2.

During the telephone interview, researchers asked the patients if they had experienced a sudden onset of an altered sense of smell or taste in the two weeks before the swab through completion of the Sino-nasal Outcome Test 22 (SNOT-22). The SNOT-22 grades symptom severity as none (0), very mild (1), mild or slight (2), moderate (3), severe (4), or as bad as it can be (5).

Of 374 eligible patients, contact information was available for 283 and 202, 71.4%, completed the telephone survey. The participants, 52% women, had median age of 56 years.

The authors report that any altered sense of smell or taste was reported by 130 patients (64.4%, 95% CI, 57.3%-71.0%), with a median SNOT-22 score of 4 (interquartile range, 3-5); although 23.8% reported a score of 5.

Of 130 patients reporting an altered sense of smell or taste, 45 (34.6%) also reported blocked nose. Other frequent symptoms were fatigue (68.3%), dry or productive cough (60.4%), and fever (55.5%).

“Among all patients, the timing of an altered sense of smell or taste onset in relation to other symptoms occurred before other symptoms in 24 (11.9%); at same time as in 46 (22.8%); and after other symptoms in 54 (26.7%; Table 2),” the authors write. “An altered sense of smell or taste was reported as the only symptom by 6 patients (3.0%).”

They add that an altered sense of smell or taste was more frequent among 105 women (72.4%, 95% CI: 62.8%-80.7%) than among 97 men (55.7%, 95% CI: 45.2%-65.8%; P = .02).

“Alterations in smell or taste were frequently reported by mildly symptomatic patients with SARS-CoV-2 infection and often were the first apparent symptom,” according to the researchers, although they caution that the information was self-reported and included a small sample.

The authors advise, “If these results are confirmed, consideration should be given to testing and self-isolation of patients with new onset of altered taste or smell during the COVID-19 pandemic.”

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