Effectiveness of face masks for reducing transmission of SARS-CoV-2: a rapid systematic review

Abstract

This rapid systematic review of evidence asks whether (i) wearing a face mask, (ii) one type of mask over another and (iii) mandatory mask policies can reduce the transmission of SARS-CoV-2 infection, either in community-based or healthcare settings. A search of studies published 1 January 2020–27 January 2023 yielded 5185 unique records. Due to a paucity of randomized controlled trials (RCTs), observational studies were included in the analysis. We analysed 35 studies in community settings (three RCTs and 32 observational) and 40 in healthcare settings (one RCT and 39 observational). Ninety-five per cent of studies included were conducted before highly transmissible Omicron variants emerged. Ninety-one per cent of observational studies were at ‘critical’ risk of bias (ROB) in at least one domain, often failing to separate the effects of masks from concurrent interventions. More studies found that masks ( n = 39/47; 83%) and mask mandates ( n = 16/18; 89%) reduced infection than found no effect ( n = 8/65; 12%) or favoured controls ( n = 1/65; 2%). Seven observational studies found that respirators were more protective than surgical masks, while five found no statistically significant difference between the two mask types. Despite the ROB, and allowing for uncertain and variable efficacy, we conclude that wearing masks, wearing higher quality masks (respirators), and mask mandates generally reduced SARS-CoV-2 transmission in these study populations. This article is part of the theme issue 'The effectiveness of non-pharmaceutical interventions on the COVID-19 pandemic: the evidence'.

Executive Summary to the Royal Society report “COVID-19: examining the effectiveness of non-pharmaceutical interventions”

“…For the purpose of this report, two approaches were taken to considering the evidence accrued during the pandemic on the effectiveness of NPIs. The first approach was to conduct six evidence reviews [ 5 – 10 ] examining each of the NPIs individually to examine what has been learnt about their effectiveness. Despite all of the caveats about the difficulties of interpreting data from observational studies, clear signals of effectiveness against transmission of SARS-CoV-2 could be discerned from the evidence reviews for several specific measures.…”

Influenza mortality as an indicator of the effectiveness of public health interventions and their impact on United States COVID mortality

“…Furthermore, almost every intervention has, at some point, been declared ineffective, including masking, 7,8 routine testing, 9 school closures, 10 and business "lockdowns". 11,12 Meta-analyses of studies of the efficacy of individual NPIs have tended to find beneficial effects [13][14][15] with a few prominent exceptions. 7,8 Closures of businesses and schools, limits on social gathering, travel restrictions, social distancing rules, masking mandates, and other NPI's act in concert to reduce the transmission of respiratory infections.…”

“…Meta-analyses of studies of the efficacy of individual NPIs have tended to find beneficial effects 13–15 with a few prominent exceptions. 7,8 Closures of businesses and schools, limits on social gathering, travel restrictions, social distancing rules, masking mandates, and other NPI’s act in concert to reduce the transmission of respiratory infections.…”

Post-COVID-19: Time to Change Our Way of Life for a Better Future

“…There is much more to say about the SARS-2 coronavirus, including variants [ 12 , 13 , 14 ], virology [ 15 , 16 ], pathophysiology [ 17 , 18 ], diagnosis, prevention [ 19 , 20 , 21 , 22 , 23 , 24 , 25 ], treatment [ 26 , 27 , 28 , 29 ], mortality, etc. While these topics are well documented elsewhere, they are also well beyond the scope of the present investigation.…”