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.

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Objective: The innominate artery is considered an alternative site for establishing cardiopulmonary bypass in surgical procedures involving the thoracic aorta. This systematic review examines the use of innominate artery cannulation in aortic surgery.Methods: A systematic literature search was undertaken among the four major databases (PubMed, Embase, Scopus, and Ovid) to identify all studies that utilized innominate artery cannulation for establishing cardiopulmonary bypass and providing cerebral perfusion in thoracic aortic surgery. The data were reviewed up to September 2018.Results: Acute type A aortic dissection contributed to 36% (n = 818) of the total 2,290 patients. 31.5% (n = 719) underwent surgery on the aortic root only; 54.5% (n = 1246) had ascending and hemi-arch replacement, while 11.5% had total aortic arch replacement and 2.5% had a frozen elephant trunk inserted. Postoperative stroke rate was 1.25% (n = 28), temporary neurological deficit was 4.8% (n = 111). All-cause 30-day mortality rate was 2.7% (n = 61).Conclusion: Innominate artery cannulation is a safe technique in patients who undergo thoracic aortic surgery. It can be utilized, in selected cases, as a reliable route for establishing cardiopulmonary bypass and maintaining cerebral perfusion. K E Y W O R D S aorta, aortic surgery, cannulation, innominate artery

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