Current best evidence for clinical care (more info)
INTRODUCTION: Synthesis of the available evidence on the effectiveness of medical and cloth facemask use by the general public in community settings is required to learn lessons for future respiratory epidemics/pandemics.
METHOD: Search terms relating to facemasks, infection and community settings were used for PubMed, the Cochrane Library Database and Google Scholar. A meta-analysis was conducted using a random-effects model.
RESULTS: The review included 12 primary studies on the effectiveness of medical facemask use to prevent influenza, influenza-like illness, SARS-CoV, and SARS-CoV-2 transmission. The meta-analysis demonstrated that facemask use significantly reduces the risk of transmitting these respiratory infections (pooled OR = 0.66, 95% CI 0.54-0.81). Of the 12 studies, 10 clinical trials suggested that respiratory infection incidence is lower with high medical facemask compliance, early use and use in combination with intensive hand hygiene. One cohort study conducted during the SARS-CoV-2 pandemic demonstrated that facemasks are effective in reducing SARS-CoV-2 transmission when used before those who are infected develop symptoms. One case-control study reported that controls used medical facemasks more often than cases infected with SARS-CoV (p < 0.05). No primary study on cloth facemask effectiveness to prevent respiratory infection transmission was found.
CONCLUSION: Based on the available evidence, medical facemask use by healthy and sick individuals is recommended for preventing respiratory infection transmission in community settings. Medical facemask effectiveness is dependent on compliance and utilization in combination with preventive measures such as intensive hand hygiene. No direct evidence is currently available in humans supporting the recommendation of cloth facemask use to prevent respiratory infection transmission.
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The authors of this systematic review of community face mask wearing did not cite the relevant key meticulously conducted Cochrane systematic review by Jefferson. In their forest plots they analysed together RCTs, a case control study Wu 2004 and a retrospective cohort study Wang 2020. These studies are tiny with few events so did not affect the results substantially. Nevertheless the over-all results cannot be reported. The reviewers and editor should have identified these problems.
This is a very important review. The use of systematic ways in finding, appraising, and combining evidences is the strength of this review. The pooled analysis showed that face mask is effective for preventing infection transmission. This is a very important information during the pandemic of COVID-19. The data came from majority small trials. Further trials are still needed. Further trials about the combination with the surgical mask are also warranted.