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.

CBT for anxious children is an effective treatment with or without active parental involvement. However, CBT with active parental involvement emphasizing CM or TC may support long-term maintenance of treatment gains. RESULTS should be replicated as additional RCTs are published.

Background: Investigations of age effects on youth anxiety outcomes in randomized trials (RCTs) of cognitive behavior therapy (CBT) have failed to yield a clear result due to inadequate statistical power and methodologic weaknesses. We conducted an individual patient data metaanalysis to address this gap. Question: Does age moderate CBT effect size, measured by a clinically and statistically

Objective:We conducted an expedited knowledge synthesis (EKS) to facilitate evidenceinformed decision making concerning youth suicide prevention, specifically school-based strategies and nonschool-based interventions designed to prevent repeat attempts.Methods: Systematic review of review methods were applied. Inclusion criteria were as follows: systematic review or meta-analysis; prevention in youth 0 to 24 years; peer-reviewed English literature. Review quality was determined with AMSTAR (a measurement tool to assess systematic reviews). Nominal group methods quantified consensus on recommendations derived from the findings. Results:No included review addressing school-based prevention (n = 7) reported decreased suicide death rates based on randomized controlled trials (RCTs) or controlled cohort studies (CCSs), but reduced suicide attempts, suicidal ideation, and proxy measures of suicide risk were reported (based on RCTs and CCSs). Included reviews addressing prevention of repeat suicide attempts (n = 14) found the following: emergency department transition programs may reduce suicide deaths, hospitalizations, and treatment nonadherence (based on RCTs and CCSs); training primary care providers in depression treatment may reduce repeated attempts (based on one RCT); antidepressants may increase short-term suicide risk in some patients (based on RCTs and meta-analyses); this increase is offset by overall population-based reductions in suicide associated with antidepressant treatment of youth depression (based on observational studies); and prevention with psychosocial interventions requires further evaluation. No review addressed sex or gender differences systematically, Aboriginal youth as a special population, harm, or cost-effectiveness. Consensus on 6 recommendations ranged from 73% to 100%.