INTRODUCTION: The coronavirus disease 19 (COVID-19) pandemic, caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), progresses globally, and means to reduce the transmission are needed. In the community, the use of face masks is increasing world-wide, but documentation for the efficacy of this remedy is lacking. This trial investigates whether the use of face masks in the community will reduce wearers' risk of SARS-CoV-2 infection.

METHODS: This study will be a two-arm, unblinded, randomised controlled trial. We will include adults (>18 years of age) without prior confirmed COVID-19 or symptoms suggestive of COVID-19, who spend more than three hours per day outside the home with exposure to other people. A total of 6,000 participants are randomly assigned 1:1 to use face masks or not for a 30-day period during the pandemic. Participants will perform self-testing; quick test for SARS-CoV-2 antibodies (immunoglobulin M (IgM) and immunoglobulin G (IgG)) (the Livzon lateral flow test) and oropharyngeal/nasal swabs for viral detection using polymerase chain reaction (PCR). The primary endpoint following the 30-day study period is the difference in the number of SARS-CoV-2-infected individuals between the two study groups as assessed by a positive nasopharyngeal swap, a positive antibody test or a hospital-based diagnosis of SARS-CoV-2 infection.

CONCLUSIONS: We will study whether a face mask protects the wearer of the mask against SARS-CoV-2 infection. The findings are expected to apply to the present pandemic and to future viral outbreaks and to provide evidence for authority recommendations across the world.

FUNDING: This study was funded by Salling Fondene.

TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04337541.