Materials and methods
This is a cross-sectional study conducted from March 10th 2020 to March 30th 2020 at the ENT clinic of the University of Eastern Piedmont, Ospedale Maggiore della Carità in Novara, Italy.  The study was carried out in accordance with the ethical standards of the Helsinki Declaration and was approved by the local ethical review board (Comitato Etico Interaziendale n.88/2020).
The study included a convenience sample of SARS-CoV-2 polymerase chain reaction (PCR) confirmed cases being admitted for care or assessed and discharged during the study period.
Patients with confirmed SARS-CoV-2 infection were prospectively identified and recorded.
Administrative data were extracted from hospital databases and patients were offered a follow-up interview. Patients were informed about the study and asked to participate at the time of the follow-up interview (= or > 14 days from diagnosis). Interviews were carried out by two attending physicians either in person or by phone using a structured questionnaire. Inclusion criteria were: Age > 18-year old, informed consent and laboratory proven SARS-CoV-2 infection with a mild or moderate presentation of COVID-19 according to the severity classification of the Massachusetts General Hospital COVID-19 treatment guidance.15
Exclusion criteria were: declined informed consent, severe form of COVID-19.
Interview data was anonymously collected and no reward was offered for participation.
The questionnaire consisted of 22 questions, including general demographic information (age, gender), medical history (comorbidities, risks factors), SARS-CoV-2 related questions (risk exposure for occupational/family reasons, duration of infection, symptoms – fever, cough, dyspnea, fatigue or muscle pain, diarrhea or nausea) and specific information about the sense of smell and about taste (presence/absence, 0 to 10 numeric rating scale (NRS) of smell at baseline, during infection, after 14 days and at answering time - were 0 is “no sense of smell/taste” and 10 is “normal sense of smell/taste”, time of onset/recovery). The survey is available in the supplementary online material. A clinically significant change in smell of taste perception was defined as having a score difference equal or greater than two points between study times.