Loeb 2022.

Methods	Multicentre, randomised, non‐inferiority trial
Participants	1009 healthcare workers who provided direct care to patients with suspected or confirmed COVID‐19. Conducted in 29 healthcare facilities in Canada, Israel, Pakistan, and Egypt from 4 May 2020 to 29 March 2022.
Interventions	Use of medical masks versus fit‐tested N95 respirators for 10 weeks, plus universal masking, which was the policy implemented at each site.
Outcomes	The primary outcome was confirmed COVID‐19 on reverse transcriptase polymerase chain reaction (RT‐PCR) test.
Notes	Financial support was given by the Canadian Institutes of Health Research, World Health Organization, and Juravinski Research Institute. Disclosures can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M22-1966