Mehdi Bakhshaee - Sinus and Surgical Endoscopic Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
Maral Barzegar-Amini - Allergy Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
Zohreh Motedayen - Department of Otolaryngology, Mashhad University of Medical Sciences, Mashhad, Iran.
Roshanak Khojasteh-Taheri - Department of Microbiology, Faculty of Science, Neyshaboor Branch, Islamic Azad University, Neyshaboor, Iran. Department of Research, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
Mahdi Rafiee - Student Research Committee, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
Mahnaz Amini - Lung Disease Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
Parvaneh Layegh - Department of Radiology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
Kamila Hashemzadeh - Rheumatic Disease Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
Delaram Omidvar - Department of Internal Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
Peter H. Hwang - Department of Rhinology & Endoscopic Skull Base Surgery, Stanford University School of Medicine, Palo Alto, California.
Masoomeh Hosseinpoor - Department of Otolaryngology, Mashhad University of Medical Sciences, Mashhad, Iran.

Introduction: The current study aimed at investigating the occurrence and features of olfactory dysfunction in patients with confirmed coronavirus disease ۲۰۱۹ (COVID-۱۹) infection.   Materials and Methods: Patients with laboratory and clinically confirmed COVID-۱۹ infection were enrolled in this longitudinal study. They were managed in either the inpatient or outpatient setting. The demographic, clinical, and outcome data were retrieved from patients’ medical records. Olfactory dysfunction features, including the onset pattern, duration, and recovery time were investigated. The visual analog scale (VAS) was utilized as a self-rating subjective measurement of olfactory function.   Results: According to the results, the mean age of the patients (n=۵۰۲) was obtained at ۴۶.۸±۱۸.۵ years; moreover, ۵۲.۴% and ۴۷.۶% of cases were female and male, respectively. It was also revealed that ۳۵.۴% and ۶۴.۵% of the subjects were outpatients and hospitalized, respectively. Based on the findings, ۱۷۸ (۳۸.۴%) subjects had olfactory dysfunction. The mean values of VAS in hyposmic patients were estimated at ۲.۵±۲.۵, ۸.۳ ±۲.۱, and ۹.۴±۱.۶ at the first evaluation, in ۲ weeks, and after ۱ month of follow-up (p <۰.۰۰۱). The onset of olfactory dysfunction was more suddenly (۵۸.۷%). The majority of cases experienced olfactory dysfunction at the same time as other symptoms ۷۲(۵۱.۱%). Based on the results, ۰.۴% of subjects infected with COVID-۱۹ had olfactory dysfunction as an isolated symptom. The olfactory dysfunction was recovered after ۲ weeks in ۱۸ (۲۵.۳%) anosmic and ۳۷(۴۶.۸%) hyposmic patients.   Conclusion: Olfactory dysfunction seemed to be an important symptom of COVID-۱۹ infection. The occurrence of this disturbance as a transient self-limited condition was significantly higher among female subjects. 

COVID-۱۹, Olfactory dysfunction, Smell disorder