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

•This systematic review and meta-analysis evaluated the effectiveness of the use of masks to prevent SARS-CoV-2 transmission.•This study demonstrated the protective effects of masks against COVID-19 infection on HCWs and other populations.•The detailed analysis in different populations, countries and mask types were conducted to better clarify the effectiveness of wearing masks. Based on the 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. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement was consulted to report this systematic review. 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, VIP (Chinese) database. There were no language restrictions. This study was registered with PROSPERO under the number CRD42020211862. A total of 6 studies were included, involving 4 countries, after a total of 5,178 eligible articles were searched in databases and references. 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, I2 = 54.1%). For the healthcare workers group, masks were shown to have a reduced risk of infection by nearly 70%. Sensitivity analysis showed that the results were robust. The results of this systematic review and meta-analysis support the conclusion that wearing a mask could reduce the risk of COVID-19 infection. Robust randomized trials are needed in the future to better provide evidence for these interventions.