A Randomized Controlled Trial
Background:
Observational evidence suggests that mask wearing mitigates transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It is uncertain if this observed association arises through protection of uninfected wearers (protective effect), via reduced transmission from infected mask wearers (source control), or both.
Objective:
To assess whether recommending surgical mask use outside the home reduces wearers‘ risk for SARS-CoV-2 infection in a setting where masks were uncommon and not among recommended public health measures.
Design:
Randomized controlled trial (DANMASK-19 [Danish Study to Assess Face Masks for the Protection Against COVID-19 Infection]). (ClinicalTrials.gov: NCT04337541)
