Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: a systematic review and meta-analysis

Abstract

Background Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes COVID-19 and is spread personto-person through close contact. We aimed to investigate the effects of physical distance, face masks, and eye protection on virus transmission in health-care and non-health-care (eg, community) settings. MethodsWe did a systematic review and meta-analysis to investigate the optimum distance for avoiding person-toperson virus transmission and to assess the use of face masks and eye protection to prevent transmission of viruses. We obtained data for SARS-CoV-2 and the betacoronaviruses that cause severe acute respiratory syndrome, and Middle East respiratory syndrome from 21 standard WHO-specific and COVID-19-specific sources. We searched these data sources from database inception to May 3, 2020, with no restriction by language, for comparative studies and for contextual factors of acceptability, feasibility, resource use, and equity. We screened records, extracted data, and assessed risk of bias in duplicate. We did frequentist and Bayesian meta-analyses and random-effects metaregressions. We rated the certainty of evidence according to Cochrane methods and the GRADE approach. This study is registered with PROSPERO, CRD42020177047. FindingsOur search identified 172 observational studies across 16 countries and six continents, with no randomised controlled trials and 44 relevant comparative studies in health-care and non-health-care settings (n=25 697 patients). Transmission of viruses was lower with physical distancing of 1 m or more, compared with a distance of less than 1 m (n=10 736, pooled adjusted odds ratio [aOR] 0•18, 95% CI 0•09 to 0•38; risk difference [RD] -10•2%, 95% CI -11•5 to -7•5; moderate certainty); protection was increased as distance was lengthened (change in relative risk [RR] 2•02 per m; p interaction =0•041; moderate certainty). Face mask use could result in a large reduction in risk of infection (n=2647; aOR 0•15, 95% CI 0•07 to 0•34, RD -14•3%, -15•9 to -10•7; low certainty), with stronger associations with N95 or similar respirators compared with disposable surgical masks or similar (eg, reusable 12-16-layer cotton masks; p interaction =0•090; posterior probability >95%, low certainty). Eye protection also was associated with less infection (n=3713; aOR 0•22, 95% CI 0•12 to 0•39, RD -10•6%, 95% CI -12•5 to -7•7; low certainty). Unadjusted studies and subgroup and sensitivity analyses showed similar findings.Interpretation The findings of this systematic review and meta-analysis support physical distancing of 1 m or more and provide quantitative estimates for models and contact tracing to inform policy. Optimum use of face masks, respirators, and eye protection in public and health-care settings should be informed by these findings and contextual factors. Robust randomised trials are needed to better inform the evidence for these interventions, but this systematic appraisal of currently best available evidence might inform interim guidance.Funding World Health Organization.

Factors impacting social distancing measures for preventing coronavirus disease 2019 [COVID-19]: A systematic review

“…Early diagnosis and prompt management of con rmed cases by isolating (physical distance), timely follow-up and quarantine recommendations (14 days) for close contacts of a case constitute the CORE of COVID-19 control. This nding is consistent with conclusions of a study conducted by Chu et al [29] i.e. "The risk for infection is highly dependent on distance to the individual infected and the type of face mask and eye protection worn.…”

Modeling the Impact of School Reopening on SARS-CoV-2 Transmission

“…In this model, contact suppression was calculation as a percentage of baseline, prepandemic contact patterns. Reducing the number of effective daily contacts could occur via complete removal of a speci c proportion of typical contacts, or by use of other non-pharmaceutical interventions such as facial coverings and physical distancing, which might proportionally reduce risk of transmission during any individual encounter, [8] but which were not included as discrete variables in this model. Additional strategies for reducing the frequency of close contacts within school settings have been proposed by the World Health Organization and the Centers for Disease Control and Prevention, such as eliminating large group activities, reducing student movement, and allowing for a mixture of in-class and remote learning to reduce classroom size and density [9,10].…”

The Asymptomatic Infection of COVID-19 Risen in Imported Population in Shenzhen, China

“…The infection spreads easily from person to person with convenient transmitting media. Therefore, taking strong control measures against the sources of infection, cutting off the routes of transmission, enhancing social distancing, and improving the protection capability of all people are optimal strategies to combat the infection [20]. WHO has termed this approach as "Non-pharmacological Intervention," or the "Blocking Strategy" [21,22].…”