Face masks to prevent transmission of COVID-19: a systematic review and meta-analysis

Background Based on the current status of the COVID-19 global pandemic, there is an urgent need to systematically evaluate the effectiveness of wearing masks to protect public health from COVID-19 infection. Methods We conducted a systematic review and meta-analysis to evaluate the effectiveness of using face masks to prevent the spread of SARS-CoV-2. Relevant articles were retrieved from PubMed, Web of Science, ScienceDirect, Cochrane Library, and Chinese National Knowledge Infrastructure (CNKI), VIP (Chinese) database. There were no language restrictions. This study was registered with PROSPERO under the number CRD42020211862. Results A total of 6 case-control studies were included. In general, wearing a mask was associated with a significantly reduced risk of COVID-19 infection (OR = 0.38, 95% CI = 0.21-0.69, I 2 = 54.1%). Heterogeneity modifiers were investigated by subgroup analysis. For healthcare workers group, masks were shown to have a reduce risk of infection by nearly 70%. Studies in China showed a higher protective effect than other countries. Adjusted estimates and subgroup analyses showed similar findings. Conclusions The results of this systematic review and meta-analysis support the conclusion that wearing a mask could reduce the risk of COVID-19 infection.