Sudden hyposmia as a prevalent symptom of COVID-19 infection.

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) has recently caused a pandemic that has involved Italy as the second worldwide nation in terms of infected patients and deaths. The clinical manifestation of Covid-19 ranges from asymptomatic carrier status to severe pneumonia. Asymptomatic individuals in Covid-19 are those who are carriers of the virus but do not show clinical symptoms and are able to transmit the disease in the same degree as symptomatic carriers. In order to contain contagions is of supreme importance to identify asymptomatic patients because this subpopulation is one of the main factors contributing to the spread of this disease. We report on six Italian patients with COVID-19 who presented sudden hyposmia as the only or most prominent disease manifestation, without upper or lower respiratory tract involvement or other major features of the disease. A supra-threshold olfaction test confirmed the hyposmia in all patients. The onset of hyposmia during a Covid-19 outbreak should be considered as a warning sign of an infection that requires a diagnostic test for Covid-19