The perceived benefits of a One Health approach are largely hinged on increasing public health efficiency and cost effectiveness through a better understanding of disease risk–through shared control and detection efforts, and results that benefit human, animal and ecosystem health. However, there have been few efforts to identify and systematize One Health metrics to assess these perceived efficiencies. Though emphasis on the evaluation of One Health has increased, widely cited benefits of One Health approaches have mainly been based on modeled projections, rather than outcomes of implemented interventions. We conducted a review of One Health literature to determine the current status of One Health frameworks and case studies reporting One Health metrics. Of 1839 unique papers, only 7 reported quantitative outcomes; these assessments did not follow shared methodology and several reviewed only intermediate outcomes. For others, the effectiveness of One Health approaches was often assumed without supporting evidence or determined subjectively. The absence of a standardized framework to capture metrics across disciplines, even in a generic format, may hinder the more widespread adoption of One Health among stakeholders. We review possible outcome metrics suitable for the future evaluation of One Health, noting the relevance of cost outcomes to the three main disciplines associated with One Health.

A One Health approach is critical to strengthening health security at country, regional, and global levels. However, operationally its uptake remains limited. Recent momentum in assessing capacity to effectively prevent, detect, and respond to disease threats has resulted in identification of gaps that require dedicated action. This article highlights relevant tools, standards, and guidance to assist countries and institutions in meeting the collective vision articulated at the 2018 Prince Mahidol Award Conference on ''Making the World Safe from the Threats of Emerging Infectious Diseases.'' Taking stock of assessment findings, resources, priorities, and implementation initiatives across human and animal health, environment and disaster risk reduction sectors can help expand participation in global health security, target risk drivers, and form synergies for collective action and shared gains for both emerging and endemic disease challenges. In addition to health security gains, a multisectoral, One Health approach can drive benefits for wider health sector and global development goals.

Research and policy processes in many fields, such as sustainability and health, are increasingly relying on transdisciplinary cooperation among a multitude of governmental, nongovernmental, and private actors from local to global levels. In the absence of hierarchical chains of command, multistakeholder governance may accommodate conflicting or diverse interests and facilitate collective action, but its effectiveness depends on its capacity to integrate systems, transformation, and target knowledge. Approaches to foster such governance are nascent and quickly evolving, and methodological standards to facilitate comparison and learning from best practice are needed. However, there is currently no evaluation approach that (i) comprehensively assesses the capacity for knowledge integration in multistakeholder governance, (ii) draws on the best available knowledge that is being developed in various fields, and (iii) combines a systematic and transferable methodological design with pragmatic feasibility. We brought together 20 experts from institutions in nine countries, all working on evaluation approaches for collaborative sciencepolicy initiatives. In a synthesis process that included a 2-day workshop and follow-up work among a core group of participants, we developed a tool for evaluating knowledge integration capacity in multistakeholder governance (EVOLvINC). Its 23 indicators incorporate previously defined criteria and components of transdisciplinary evaluations into a single, comprehensive framework that operationalizes the capacity for integrating systems, target, and transformation knowledge during an initiative's (a) design and planning processes at the policy formulation stage, (b) organization and working processes at the implementation stage, and (c) sharing and learning processes at the evaluation stage of the policy cycle. EVOLvINC is (i) implemented through a questionnaire, (ii) builds on established indicators where possible, (iii) offers a consistent and transparent semiquantitative scoring and aggregation algorithm, and (iv) uses spider diagrams for visualizing results. The tool builds on experience and expertise from both the northern and southern hemispheres and was empirically validated with seven science-policy initiatives in six African and Asian countries. As a generalized framework, EVOLvINC thus enables a structured reflection on the capacity of multistakeholder governance processes to foster knowledge integration. Its emphasis on dialog and exploration allows adaptation to contextual specificities, highlights relative strengths and weaknesses, and suggests avenues for shaping multistakeholder governance toward mutual learning, capacity building, and strengthened networks. The validation suggests that the adaptive capacity of multistakeholder governance could be best enhanced by considering systems characteristics at the policy formulation stage and fostering adaptive and generic learning at the evaluation stage of the policy cycle.

Global economic impacts of epidemics suggest high return on investment in prevention and One Health capacity. However, such investments remain limited, contributing to persistent endemic diseases and vulnerability to emerging ones. An interdisciplinary workshop explored methods for country-level analysis of added value of One Health approaches to disease control. Key recommendations include: 1. systems thinking to identify risks and mitigation options for decision-making under uncertainty; 2. multisectoral economic impact assessment to identify wider relevance and possible resource-sharing, and 3. consistent integration of environmental considerations. Economic analysis offers a congruent measure of value complementing diverse impact metrics among sectors and contexts.