BackgroundDevelopment of a core outcome set (COS) for clinical trials for COVID-19 is urgent because of the pandemic wreaking havoc worldwide and the heterogeneity of outcomes in clinical trials. MethodsA preliminary list of outcomes was developed after a systematic review of protocols of clinical trials for COVID-19. Then. two rounds of the Delphi survey were conducted. http://foldlyers.shop/product-category/on-ear/