Sudden olfactory loss as an early marker of COVID-19: a nationwide Italian survey.

The presence of many asymptomatic COVID-19 cases may increase the risks of disease dissemination, mainly for physicians. There are numerous reports on the frequent findings of sudden anosmia or hyposmia, before or at the same time of the typical COVID-19 symptoms onset. The aim of this study was to verify the association of olfactory impairment and COVID-19, providing a basis for subsequent research in the field of COVID-19 clinical heterogeneity. We developed a 15-item online questionnaire on "Sudden Olfactory Loss (SOL) and COVID-19" that was administered during March 2020 to Italian general practitioners registered to a social media group. One hundred and eighty responses were received. SOL was identified as a significant sign of infection in COVID-19 patients, mainly aged between 30 and 40 years, even in the absence of other symptoms. SOL was present as an initial symptom in 46.7% of subjects, and in 16.7%, it was the only symptom. Among the COVID-19 confirmed cases, SOL occurred as the only symptom in 19.2% of patients. SOL could represent a possible early symptom in otherwise asymptomatic COVID-19 subjects. Subjects affected by SOL should be considered as potential COVID-19 cases. 4.