Taste alteration in COVID-19: a rapid review with data synthesis reveals significant geographical differences

To facilitate a timely understanding of the differences in the prevalence of gustatory disturbances (GD) in individuals infected with SARS-CoV-2, we undertook a rapid systematic review of articles published in the repository of the National Library of Medicine (MEDLINE/PubMed) and medRxiv from their inception until September 3, 2020. The minimum requirements for completing a restricted systematic review were met. Of the 431 articles retrieved, 61 eligible studies (28,374 confirmed COVID-19 cases) from 20 countries were included in the analysis. The results show strong significant differences in the overall reported prevalence of GD between East Asia [13%, 95% CI 0.14-26.06%], Middle East [38.83%, 95% CI 27.47-50.19%], Europe [57.18%, 95% CI 52.35-62.01%], and The Americas [66.78%, 95% CI 54.77-78.79%]. There were no trends showing differences of GD prevalence in the available literature between February and August, 2020. These data show that there is a distinct geographical distribution of GD in COVID-19 patients and this may explain the differences of diagnostic criteria for COVID-19 case definition.