22 April 2022, This document provides updated interim recommendations on the use of masks by health workers providing care to patients with suspected or confirmed COVID-19. This update is prompted by new evidence around mask use and COVID-19 transmission, as well as the emergence of variants of concern including Omicron. Masks continue to be a critical tool to prevent the spread of COVID-19. These interim guidelines supersede the recommendations provided in the WHO recommendations on mask use by health workers, in light of the Omicron variant of concern published on 22 December 2022. WHO continually evaluates the emerging evidence and will review these interim recommendations within two months and issue new guidance as needed.