Is loss of sense of smell a diagnostic marker in COVID-19: A systematic review and meta-analysis.

Our review has shown that there is already significant evidence which demonstrates an association between OD and the novel coronavirus-COVID-19. It is unclear if this finding is unique to this coronavirus as individual viral phenotypes rarely present in such concentrated large numbers. We have demonstrated that OD is comparatively more predictive for COVID-19 positivity compared to other associated symptoms. We recommend that people who develop OD during the pandemic should be self-isolate and this guidance should be adopted internationally to prevent transmission.