BACKGROUND AND PURPOSE:

• Chu et al. (Lancet, 2020) investigated the effects of physical distance, face masks, and eye protection on SARS-CoV-2 and other virus transmission in both healthcare and non-healthcare settings

METHODS:

• Systematic review and meta-analysis
• Data sources
  • 21 standard WHO-specific and COVID-19-specific sources from database inception to May 3, 2020
• Inclusion criteria
  • Comparative studies and data on
    • Acceptability | Feasibility | Resource use | Equity
• Study design
  • Data were obtained for
    • SARS-CoV-2
    • Betacoronaviruses
    • MERS
  • Authors screened records, extracted data | Data duplication bias also assessed
  • Certainty of evidence was rated according to Cochrane methods and the GRADE criteria
• Primary outcomes
  • Optimum distance for avoiding person-to-person virus transmission
  • Virus transmission with use of face masks and eye protection

RESULTS:

• 172 observational studies | 44 comparative studies | 25,697 patients | Across 16 countries
• Transmission of viruses was lower with physical distancing of ≥1 meter (3.28 feet) vs <1 meter
  • 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)
• Protection against transmission increased as distance increased
  • Change in relative risk (RR) 2.02 per meter
• Face mask use could result in a large reduction in risk of transmission
  • aOR 0.15 (95% CI, 0.07 to 0.34)
  • RD −14.3% (95% CI, −15.9 to −10.7)
• For exposed individuals, N95 or similar respirators or face masks (eg, disposable surgical masks) were associated with reduced infection risk
  • Adjusted aOR 0.15 (95% CI, 0.07 to 0.34)
  • Association strongest in healthcare setting
    • Health-care settings: RR 0.30 (95% CI, 0.22 to 0.41)
    • Non-healthcare settings: RR 0.56 (95% CI, 0.40 to 0.79)
• Reduced transmission risk was more strongly associated with N95 of similar respirators vs disposable surgical masks
  • N95 or similar respirators: aOR 0.04 (95% CI, 0.004 to 0.30)
  • Other masks: aOR 0.33 (95% CI, 0.17 to 0.61)
• Use of eye protection was also associated with reduced infection
  • aOR 0.22 (95% CI, 0.12 to 0.39)
  • RD −10.6% (95% CI, −12.5 to −7.7)
• Unadjusted studies and subgroup and sensitivity analyses showed similar findings

CONCLUSION:

• This systematic review and meta-analysis found support for maintaining physical distance of at least 1 meter to reduce viral transmission
• Use of face masks and eye protection were also associated with reduced infection
• Authors recognize that lack of RCTs is an important study limitation, however, based on the best available evidence

Current policies of at least 1 m physical distancing are associated with a large reduction in infection, and distances of 2 m might be more effective

These data also suggest that wearing face masks protects people (both health-care workers and the general public) against infection by these coronaviruses, and that eye protection could confer additional benefit

Learn More – Primary Sources:

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

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