Demographic, epidemiological and clinical outcomes
The following demographic and epidemiological data were collected with a standardized online questionnaire: gender; age; ethnicity; smoking and comorbidities (i.e. heart, respiratory, kidney, liver, neurological, autoimmune diseases, diabetes, hypertension and gastroduodenal disorders). Mild-to-moderate patients fulfilled themselves the questionnaire while physicians completed the questionnaire after anamnesis or on medical record for the hospitalized patients who were not able to electronically complete the evaluations.
From a clinical standpoint, general symptoms were assessed as present or absent. Otolaryngological symptoms were rated with a 5-point scale ranging from 0 (absent) to 4 (very severe symptoms). Both subjective olfactory and gustatory functions were assessed through items of the smell and taste component of the National Health and Nutrition Examination Survey.7