Using a consensus-based approach to build a threat assessment tool for use in a Canadian federal public health setting.

Background: Public health intelligence activities, including assessment of emerging public health threats, are core operations for many public health agencies. Threat assessment is intended to guide public health actions proportional to the assessed threat level within the context of an evolving situation. A risk-based threat assessment framework helps clarify the overall population-level health impacts of threats, guiding appropriate public health action. Objective: This work aimed to develop a standardized, risk-based tool for assessing public health threats that could be used across the Public Health Agency of Canada (PHAC), integrating diverse perspectives from various PHAC stakeholders to ensure the tool is applicable across the full entire spectrum of potential public health threats. Methods: A threat assessment framework was developed to assign an overall threat level based on the assessment of three distinct threat attributes: the severity of harm to human health, the degree to which a threat is likely to impact Canada, and Canada's capacity to prevent or mitigate the threat. A Delphi-based approach was used to develop a set of qualitative criteria enabling end-users to assign a rating of high, moderate, or low for each threat attribute and the overall assessment. Results: Three iterative surveys and two meetings led to consensus on definitions for the three threat attributes and the overall assessment, enabling a flexible framework capable of characterizing a wide range of public health threats. Conclusion: Standardized, broadly accepted definitions for threat assessment reliably characterize and communicate public health events of importance and provide support for public health action.