Risk Classification of Zoonotic Microorganisms: Development of a One Health Approach Tool Applied to HPAI A H5N1 Viruses

As pathogenic (micro)organisms constitute a biological hazard, they have been categorized into classes of risk (CR). The CR have been defined for human pathogens by the World Health Organization and for animal pathogens by the World Organization for Animal Health. A few countries have also established their own definitions and lists of pathogenic (micro)organisms with their class of risk. The aim of this paper is to propose an improved approach to strengthen the final result obtained for the classification of ill-defined or uncategorized newly (re)emerging human or animal pathogen. This approach has been tested and validated with highly pathogenic avian influenza (HPAI) A H5N1 viruses. In this one health approach, first, a questionnaire containing questions related to the criteria for biological risk assessment of a microorganism was sent to human and animal health professionals and stakeholders. After that, aggregated summary results were communicated to participating experts, after which a meeting was organized to confront the different opinions and address any remaining uncertainties. We show that a semi-quantitative approach based on expert knowledge elicitation allows circumventing limitations from purely qualitative models by confronting and critically assessing opinions of experts from different fields of expertise