Cochrane Database of Systematic Reviews to reflect our focus on RCTs and cluster-RCTs for this update. We did not contact trialists for missing data due to the urgency in completing the review. We extracted data on adverse events (harms) associated with the interventions. Main resultsWe included 44 new RCTs and cluster-RCTs in this update, bringing the total number of randomised trials to 67. There were no included studies conducted during the COVID-19 pandemic. Six ongoing studies were identified, of which three evaluating masks are being conducted concurrent with the COVID pandemic, and one is completed.Many studies were conducted during non-epidemic influenza periods, but several studies were conducted during the global H1N1 influenza pandemic in 2009, and others in epidemic influenza seasons up to 2016. Thus, studies were conducted in the context of lower respiratory viral circulation and transmission compared to COVID-19. The included studies were conducted in heterogeneous settings, ranging from suburban schools to hospital wards in high-income countries; crowded inner city settings in low-income countries; and an immigrant neighbourhood in a high-income country. Compliance with interventions was low in many studies.The risk of bias for the RCTs and cluster-RCTs was mostly high or unclear. Medical/surgical masks compared to no masksWe included nine trials (of which eight were cluster-RCTs) comparing medical/surgical masks versus no masks to prevent the spread of viral respiratory illness (two trials with healthcare workers and seven in the community). There is low certainty evidence from nine trials (3507 participants) that wearing a mask may make little or no di erence to the outcome of influenza-like illness (ILI) compared to not wearing a mask (risk ratio (RR) 0.99, 95% confidence interval (CI) 0.82 to 1.18. There is moderate certainty evidence that wearing a mask probably makes little or no di erence to the outcome of laboratory-confirmed influenza compared to not wearing a mask (RR 0.91, 95% CI 0.66 to 1.26; 6 trials; 3005 participants). Harms were rarely measured and poorly reported. Two studies during COVID-19 plan to recruit a total of 72,000 people. One evaluates medical/surgical masks (N = 6000) (published Annals of Internal Medicine, 18 Nov 2020), and one evaluates cloth masks (N = 66,000). N95/P2 respirators compared to medical/surgical masksWe pooled trials comparing N95/P2 respirators with medical/surgical masks (four in healthcare settings and one in a household setting). There is uncertainty over the e ects of N95/P2 respirators when compared with medical/surgical masks on the outcomes of clinical respiratory illness (RR 0.70, 95% CI 0.45 to 1.10; very low-certainty evidence; 3 trials; 7779 participants) and ILI (RR 0.82, 95% CI 0.66 to 1.03; low-certainty evidence; 5 trials; 8407 participants). The evidence is limited by imprecision and heterogeneity for these subjective outcomes. The use of a N95/P2 respirator compared to a medical/surgical mask probably makes little or no di erence for th...

2. Art. No.: CD004876. Cochrane Reviews are regularly updated as new evidence emerges and in response to comments and criticisms, and the Cochrane Database of Systematic Reviews should be consulted for the most recent version of the Review.

11.Art.No.:CD006207. Cochrane Reviews are regularly updated as new evidence emerges and in response to comments and criticisms, and the Cochrane Database of Systematic Reviews should be consulted for the most recent version of the Review.

Conflicts of interest (COIs) have been defined by the American Thoracic Society as "a divergence between an individual's private interests and his or her professional obligations such that an independent observer might reasonably question whether the individual's professional actions or decisions are motivated by personal gain, such as direct financial, academic advancement, clinical revenue streams, or community standing." In the context of guideline development, the concerns are not simply about identifying and disclosing direct financial or indirect COIs. Despite this recognition, the management of COIs in guidelines is often unsatisfactory. In response to requests from its international membership and informed by existing syntheses of the evidence and policies of international organizations, the Guidelines International Network Board of Trustees developed guidance on the disclosure of interests and management of COIs. Current approaches are relatively similar throughout the guideline development community, with an increasing recognition of the importance of disclosing and managing indirect COIs. Although there are differences in detail among the approaches, the similarities allow for the formulation of 9 core principles for managing COIs. In formulating these principles, the Guidelines International Network Board of Trustees recognizes that COIs cannot be totally avoided when panel members are being chosen for certain guidelines or in certain settings; thus, the important issue is the management of COIs in a fair, judicious, transparent manner.

Analysis 1.2. Comparison 1 Enteral versus parenteral nutrition for acute pancreatitis, Outcome 2 Mortality in patients with acute pancreatitis excluding those from (Abou-Assi 2002) in which death resulted a er resolution of acute pancreatitis and was attributed to other causes; cardiac surgery, cancer of the liver, squamous cell carcinoma of the pharynx and intracerebral hemorrhage..

11.Art.No.:CD006207. Cochrane Reviews are regularly updated as new evidence emerges and in response to comments and criticisms, and the Cochrane Database of Systematic Reviews should be consulted for the most recent version of the Review.

Objective To review systematically the evidence of effectiveness of physical interventions to interrupt or reduce the spread of respiratory viruses. Data sources Cochrane Library, Medline, OldMedline, Embase, and CINAHL, without restrictions on language or publication. Data selection Studies of any intervention to prevent the transmission of respiratory viruses (isolation, quarantine, social distancing, barriers, personal protection, and hygiene). A search of study designs included randomised trials, cohort, case-control, crossover, before and after, and time series studies. After scanning of the titles, abstracts and full text articles as a first filter, a standardised form was used to assess the eligibility of the remainder. Risk of bias of randomised studies was assessed for generation of the allocation sequence, allocation concealment, blinding, and follow-up. Nonrandomised studies were assessed for the presence of potential confounders and classified as being at low, medium, or high risk of bias. Data synthesis 58 papers of 59 studies were included. The quality of the studies was poor for all four randomised controlled trials and most cluster randomised controlled trials; the observational studies were of mixed quality. Meta-analysis of six case-control studies suggested that physical measures are highly effective in preventing the spread of severe acute respiratory syndrome: handwashing more than 10 times daily (odds ratio 0.45, 95% confidence interval 0.36 to 0.57; number needed to treat=4, 95% confidence interval 3.65 to 5.52), wearing masks (0.32, 0.25 to 0.40; NNT=6, 4.54 to 8.03), wearing N95 masks (0.09, 0.03 to 0

Preventing Overdiagnosis Working Group IMPORTANCE No guidelines exist currently for guideline panels and others considering changes to disease definitions. Panels frequently widen disease definitions, increasing the proportion of the population labeled as unwell and potentially causing harm to patients. We set out to develop a checklist of issues, with guidance, for panels to consider prior to modifying a disease definition.OBSERVATIONS We assembled a multidisciplinary, multicontinent working group of 13 members, including members from the Guidelines International Network, Grading of Recommendations Assessment, Development and Evaluation working group, and the World Health Organisation. We used a 5-step process to develop the checklist: (1) a literature review of issues, (2) a draft outline document, (3) a Delphi process of feedback on the list of issues, (4) a 1-day face-to-face meeting, and (5) further refinement of the checklist. The literature review identified 12 potential issues. From these, the group developed an 8-item checklist that consisted of definition changes, number of people affected, trigger, prognostic ability, disease definition precision and accuracy, potential benefits, potential harms, and the balance between potential harms and benefits. The checklist is accompanied by an explanation of each item and the types of evidence to assess each one. We used a panel's recent consideration of a proposed change in the definition of gestational diabetes mellitus (GDM) to illustrate use of the checklist. CONCLUSIONS AND RELEVANCEWe propose that the checklist be piloted and validated by groups developing new guidelines. We anticipate that the use of the checklist will be a first step to guidance and better documentation of definition changes prior to introducing modified disease definitions.