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.

Background: Coronavirus disease 2019 (COVID-19) is a global pandemic. Governments have implemented combinations of ''lockdown'' measures of various stringencies, including school and workplace closures, cancellations of public events, and restrictions on internal and external movements. These policy interventions are an attempt to shield high-risk individuals and to prevent overwhelming countries' healthcare systems, or, colloquially, ''flatten the curve.'' However, these policy interventions may come with physical and psychological health harms, group and social harms, and opportunity costs. These policies may particularly affect vulnerable populations and not only exacerbate pre-existing inequities but also generate new ones.Methods: We developed a conceptual framework to identify and categorize adverse effects of COVID-19 lockdown measures. We based our framework on Lorenc and Oliver's framework for the adverse effects of public health interventions and the PROGRESS-Plus equity framework. To test its application, we purposively sampled COVID-19 policy examples from around the world and evaluated them for the potential physical, psychological, and social harms, as well as opportunity costs, in each of the PROGRESS-Plus equity domains: Place of residence, Race/ethnicity, Occupation, Gender/sex, Religion, Education, Socioeconomic status, Social capital, Plus (age, and disability).Results:We found examples of inequitably distributed adverse effects for each COVID-19 lockdown policy example, stratified by a low-or middle-income country and high-income country, in every PROGRESS-Plus equity domain. We identified the known policy interventions intended to mitigate some of these adverse effects. The same harms (anxiety, depression, food insecurity, loneliness, stigma, violence) appear to be repeated across many groups and are exacerbated by several COVID-19 policy interventions.Conclusion: Our conceptual framework highlights the fact that COVID-19 policy interventions can generate or exacerbate interactive and multiplicative equity harms. Applying this framework can help in three ways: (1) identifying the areas where a policy intervention may generate inequitable adverse effects; (2) mitigating the policy and practice interventions by facilitating the systematic examination of relevant evidence; and (3) planning for lifting COVID-19 lockdowns and policy interventions around the world.

Background: Mechanical ventilation is used to treat respiratory failure in coronavirus disease 2019 (COVID-19). Purpose: To review multiple streams of evidence regarding the benefits and harms of ventilation techniques for coronavirus infections, including that causing COVID-19. Data Sources: 21 standard, World Health Organization-specific and COVID-19-specific databases, without language restrictions, until 1 May 2020. Study Selection: Studies of any design and language comparing different oxygenation approaches in patients with coronavirus infections, including severe acute respiratory syndrome (SARS) or Middle East respiratory syndrome (MERS), or with hypoxemic respiratory failure. Animal, mechanistic, laboratory, and preclinical evidence was gathered regarding aerosol dispersion of coronavirus. Studies evaluating risk for virus transmission to health care workers from aerosol-generating procedures (AGPs) were included. Data Extraction: Independent and duplicate screening, data abstraction, and risk-of-bias assessment (GRADE for certainty of evidence and AMSTAR 2 for included systematic reviews). Data Synthesis: 123 studies were eligible (45 on COVID-19, 70 on SARS, 8 on MERS), but only 5 studies (1 on COVID-19, 3 on SARS, 1 on MERS) adjusted for important confounders. A study in hospitalized patients with COVID-19 reported slightly higher mortality with noninvasive ventilation (NIV) than with invasive mechanical ventilation (IMV), but 2 opposing studies, 1 in patients with MERS and 1 in patients with SARS, suggest a reduction in mortality with NIV (very-low-certainty evidence). Two studies in patients with SARS report a reduction in mortality with NIV compared with no mechanical ventilation (low-certainty evidence). Two systematic reviews suggest a large reduction in mortality with NIV compared with conventional oxygen therapy. Other included studies suggest increased odds of transmission from AGPs. Limitation: Direct studies in COVID-19 are limited and poorly reported. Conclusion: Indirect and low-certainty evidence suggests that use of NIV, similar to IMV, probably reduces mortality but may increase the risk for transmission of COVID-19 to health care workers.

We found moderate- to high-quality evidence of reduced risk of cytomegalovirus infection in renal transplant recipients in the mTOR inhibitor-based compared with the calcineurin inhibitor-based regimen. Our review also suggested that a combination of a mTOR inhibitor and a reduced dose of calcineurin inhibitor may be associated with similar eGFR and rates of acute rejections and serious adverse events compared with a standard calcineurin inhibitor-based regimen at the expense of higher incidence of proteinuria and wound-healing complications.

This paper is the initial Position Statement of Evidence Synthesis International, a new partnership of organizations that produce, support and use evidence synthesis around the world. The paper (i) argues for the importance of synthesis as a research exercise to clarify what is known from research evidence to inform policy, practice and personal decision making; (ii) discusses core issues for research synthesis such as the role of research evidence in decision making, the role of perspectives, participation and democracy in research and synthesis as a core component of evidence ecosystems; (iii) argues for 9 core principles for ESI on the nature and role of research synthesis; and (iv) lists the 5 main goals of ESI as a coordinating partnership for promoting and enabling the production and use of research synthesis. Background Evidence synthesis Research can be defined as critical social enquiry for public use [2]. Research evidence is one of many factors

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Objectives: The public, policy makers, and science communities are subject to many false, uninformed, overly optimistic, premature, or simply ridiculous health claims. The coronavirus disease 2019 (COVID-19) pandemic and its context is a paramount example for such claims. In this article, we describe why expressing the certainty in evidence to support a decision is critical and why the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach matters now, perhaps more than ever and no matter what the specific topic is in relation to COVID-19. We finally also offer suggestions for how it can be used appropriately to support decision-making at global, national, and local level when emergency, urgent or rapid responses are needed.Study Design and Setting: This is an invited commentary to address the objectives above building on examples from the recent COV-ID-19 pandemic. This includes an iterative discussion of examples and development of guidance.Results: The GRADE approach is a transparent and structured method for assessing the certainty of evidence and when developing recommendations that requires little additional time. We describe why emergency, urgent, or rapid responses do not justify omitting this critical assessment of the evidence. In situations of emergencies and urgencies, such as the COVID-19 pandemic, GRADE can similarly be used to express and convey certainty in intervention effects, test accuracy, risk and prognostic factors, consequences of public health measures, and qualitative bodies of evidence.Conclusions: Assessing and communicating the certainty of evidence during the COVID-19 pandemic is critical. Those offering evidence synthesis or making recommendations should use transparent ratings of the body of evidence supporting a claim regardless of time that is available or needed to provide this response.

Published research on COVID-19 is increasing rapidly and integrated in guidelines. The trustworthiness of guidelines can vary depending on the methods used to assemble and evaluate the evidence, the completeness and transparency of reporting on the process undertaken and how conflicts of interest are addressed. With a global consortium of partners and collaborators, we have created a catalogue of COVID-19 recommendations as our direct response to the increased need for structured access to high quality guidance in the field. The COVID19 map of recommendations and gateway to contextualization ( https://covid19.recmap.org ) is a living project: emerging guideline literature is added on an ongoing basis, allowing granular access to individual recommendations. Building on prior work on mapping recommendations for the World Health Organization tuberculosis guidelines, a novel feature of this map is the self-directed contextualization of the recommendations using the GRADE-Adolopment approach to adopt, adapt or synthesize de novo recommendations for context specific questions. Through our map, stakeholders access the evidence underpinning a recommendation, select what needs to be contextualized and go through the steps of development of adapted recommendations. This one-stop shop portal of evidence-informed recommendations, built with intuitive functionalities, easy to navigate and with a support team ready to guide users across the maps, represents a long-needed tool for decision-makers, guideline developers and the public at large.