Sudden Onset, Acute Loss of Taste and Smell in Coronavirus Disease 2019 (COVID-19): A Systematic Review

Early detection, isolation, and management of COVID-19 patients are crucial to contain the current pandemic. The CDC in USA recently included "sudden loss of taste (dysgeusia/ageusia) and smell (anosmia/hyposmia)” as symptoms of COVID-19. If these symptoms are reliable forerunner symptoms of COVID-19, then it may facilitate early detection and containment of the disease. Hence, we systematically evaluated the contemporary evidence on dysgeusia and anosmia as trigger symptoms in COVID-19. Ovid MEDLINE, EBSCO host, and Web of Science databases were searched between December 25, 2019-May 30, 2020.Of the 13 identified records, eight (totaling 11,054 COVID-19 patients), were included, as per the selection criteria. The studies emanated mostly from the European community, as well as China, the USA, and Iran. In total, anosmia and dysgeusia symptoms were present in 74.9 % and 81.3% ambulatory as well as hospitalized, mild-to-severe cases of COVID-19 patients, respectively. The European, US, and Iran data indicate that olfactory, and gustatory symptoms appear prior to general COVID-19 symptoms in a majority of the patients. To our knowledge, this is the first systematic review analyzing the prevalence of chemosensory dysfunction in COVID-19. Further, studies are essential to evaluate their utility as harbingers of COVID-19 onset, and to establish clinical practice guidelines.