Background

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes COVID-19 and is spread person-to-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.

Methods

We did a systematic review and meta-analysis to investigate the optimum distance for avoiding person-to-person 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 meta-regressions. We rated the certainty of evidence according to Cochrane methods and the GRADE approach. This study is registered with PROSPERO, CRD42020177047.

Findings

Our 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.

中文翻译：

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保持身体距离、戴口罩和保护眼睛以防止 SARS-CoV-2 和 COVID-19 人际传播：系统评价和荟萃分析。

背景

严重急性呼吸综合征冠状病毒 2 (SARS-CoV-2) 会导致 COVID-19，并通过密切接触在人与人之间传播。我们的目的是调查物理距离、口罩和护目镜对医疗保健和非医疗保健（例如社区）环境中病毒传播的影响。

方法

我们进行了系统回顾和荟萃分析，以调查避免人与人之间病毒传播的最佳距离，并评估使用口罩和护目镜来防止病毒传播的情况。我们从 21 个 WHO 特定和 COVID-19 特定的标准来源获得了 SARS-CoV-2 和导致严重急性呼吸综合征和中东呼吸综合征的 β 冠状病毒的数据。我们检索了从数据库建立到 2020 年 5 月 3 日的这些数据源，不受语言限制，进行比较研究以及可接受性、可行性、资源利用和公平性的背景因素。我们一式两份地筛选记录、提取数据并评估偏倚风险。我们进行了频率论和贝叶斯荟萃分析以及随机效应荟萃回归。我们根据 Cochrane 方法和 GRADE 方法对证据的确定性进行评级。本研究已在 PROSPERO 注册，CRD42020177047。

发现

我们的搜索确定了 16 个国家和六大洲的 172 项观察性研究，没有随机对照试验，以及医疗保健和非医疗保健环境中的 44 项相关比较研究（n=25 697 名患者）。与物理距离小于 1 m 相比，物理距离为 1 m 或以上的病毒传播较低（n=10 736，合并调整比值比 [aOR] 0·18，95% CI 0·09 至 0·38 ；风险差异[RD] -10·2%，95% CI -11·5 至 -7·5；中等确定性）；保护随着距离的延长而增强（相对风险变化 [RR] 2·02 每米；p_相互作用=0·041；中等确定性）。使用口罩可大大降低感染风险（n=2647；aOR 0·15，95% CI 0·07 至 0·34，RD −14·3%，-15·9 至 -10·7 ；低确定性），与一次性外科口罩或类似口罩（例如，可重复使用的12-16层棉口罩；p相互作用= 0 _· 090；后验概率> 95％，低确定性）相比，与N95或类似呼吸器的关联性更强。眼睛保护也与较少感染相关（n=3713；aOR 0·22，95% CI 0·12 至 0·39，RD −10·6%，95% CI -12·5 至 -7·7；低肯定）。未经调整的研究以及亚组和敏感性分析显示了类似的结果。

解释

这项系统评价和荟萃分析的结果支持 1 m 或以上的物理距离，并为模型和接触者追踪提供定量估计，为政策提供信息。在公共和医疗机构中如何最佳使用口罩、呼吸器和护目镜应根据这些发现和背景因素进行指导。需要强有力的随机试验来更好地为这些干预措施提供证据，但对当前最佳可用证据的系统评估可能会为临时指南提供信息。

资金

世界卫生组织。