Self-reported Olfactory and Taste Disorders in Patients With Severe Acute Respiratory Coronavirus 2 Infection: A Cross-sectional Study

To the Editor—We read with interest the article by Wang et al [1] describing the clinical features of 69 patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in Wuhan, China. The authors provide a detailed description of major signs and symptoms of overt disease [2, 3], but fail to give an account of minor symptoms that may be present at earlier stages of the infection. After some patients admitted for coronavirus disease 2019 (COVID-19) at the Infectious Disease Department of L. Sacco Hospital in Milan, Italy, complained of olfactory and taste disorders (OTDs), we performed a cross-sectional survey of the prevalence of these alterations in the context of SARS-CoV-2 infection. On 19 March 2020, a simple questionnaire including questions about the presence or absence of OTDs, their type and time of onset respective to hospitalization were submitted through verbal interview to all SARS-CoV-2– positive hospitalized patients who were able to give informed consent. Of 88 hospitalized patients, 59 were able to be interviewed (29 were nonrespondents, of whom 4 had dementia, 2 had a linguistic barrier, and 23 were on noninvasive ventilation) (Table 1). Of these, 20 (33.9%) reported at least 1 taste or olfactory disorder and 11 (18.6%) both. Twelve patients (20.3%) presented the symptoms before the hospital admission, whereas 8 (13.5%) experienced the symptoms during the hospital stay. Taste alterations were more frequently (91%) before hospitalization, whereas after hospitalization taste and olfactory alteration appeared with equal frequency. Females reported OTDs more frequently than males (10/19 [52.6%] vs 10/40 [25%]; P = .036). Moreover, patients with at least 1 OTD were younger than those without (median, 56 years [interquartile range {IQR}, 47–60] vs 66 [IQR, 52–77]; P = .035). All patients reported the persistence of OTDs at the time of the interview. Olfactory and taste disorders are well known to be related with a wide range of viral infections [4, 5]. SARS-CoV has demonstrated in a mice model a transneural penetration through the olfactory bulb [6]. Moreover, angiotensinconverting enzyme 2 receptor, which is used by SARS-CoV-2 to bind and penetrate into the cell, is widely expressed on the epithelial cells of the mucosa of the oral cavity [7]. These findings could explain the underlying pathogenetic mechanism of taste and olfactory disorders in SARS-CoV-2 infection. Due to limitations related to the diffusivity of the disease and emergency contingencies, it was impossible to perform a more structured questionnaire associated with validated tests (ie, Pennsylvania smell identification test) [8]. However, our survey shows that OTDs are fairly frequent in patients with SARS-CoV-2 infection and may precede the onset of full-blown clinical disease. In a pandemic context, further investigations on nonhospitalized infected patients are required to ascertain if these symptoms, albeit unspecific, may represent a clinical screening tool to orientate testing of pauci-symptomatic individuals.