JUL 02, 2020
This review investigated the role of social distancing, face masks and eye protection in preventing transmission of SARS-CoV-2 and other betacoronaviruses.
This was a systematic review and meta-analysis—funded by the World Health Organization (WHO)—conducted to investigate how social distancing, face masks and eye protection affect person-to-person transmission of SARS-CoV-2 and other betacoronaviruses. Data was obtained from 21 standard WHO-specific and COVID-19-specific sources. The authors identified 172 observational studies, including 44 comparative studies, from 16 countries and 6 continents.
The review revealed that the transmission of viruses was lower with physical distancing of 1 meter or more (OR 0.18), with longer distances providing more protection (change in relative risk 2.02 per meter). The authors noted that implementation of 2 meters appears to be more effective in some countries. Eye protection also correlated with reduced infection (OR 0.22).
Use of a face mask—N95 or similar respirators, disposable surgical masks or reusable 12- to 16-layer cotton masks—conferred a large reduction in risk of infection (OR 0.15). This was particularly true for N95 masks or similar respirators compared with either cotton masks or disposable surgical masks (OR 0.04 vs. 0.33). Although these associations appeared stronger in health-care settings compared with nonhealth-care settings (RR 0.30 vs. 0.56), the differences diminished when accounting for differential use of N95 respirators.
This was a large review of published data and none of the studies were randomized controlled trials.
This review supports the importance of physical distancing to mitigate transmission of SARS-CoV-2. These findings and contextual factors can help facilitate the optimum use of face masks, respirators and eye protection in public and health-care settings. However, more robust randomized trials are still necessary.
Read the accompanying editorial to this paper: Physical distancing, face masks, and eye protection for prevention of COVID-19