Evaluation of vaccination strategies against avian influenza and Newcastle disease in poultry production networks: comparison of the EVACS tool application in several countries

Hautefeuille Claire, Dauphin Gwenaelle, Peyre Marie-Isabelle. 2023. Evaluation of vaccination strategies against avian influenza and Newcastle disease in poultry production networks: comparison of the EVACS tool application in several countries. In : 22nd World Veterinary Poultry Association (WVPA): Book of abstracts. WVPA. Vérone : WVPA, Résumé, p. 162. World Veterinary Poultry Association Congress (WVPA). 22, Vérone, Italie, 4 Septembre 2023/8 Septembre 2023.

Résumé : Highly pathogenic avian influenza (HPAI) and Newcastle disease (ND) are major threats to poultry production, both leading to production losses. HPAI infections in endemic and epizootic countries lead to exportation bans and thus to large economic impacts for all exporting poultry production networks. Additionally to surveillance and biosecurity measures, vaccination can be a tool for the control of HPAI and ND. While vaccination against ND is allowed in many countries, vaccination against avian influenza (AI) is still limited to few countries where the disease is endemic. Nonetheless, the devastating epidemiological situation faced since 2017 across the world has generated a lot of debates on the usage of vaccination and its potential strategies in an increased number of countries. The EVACS® tool (Evaluation of VACcination Strategies) has been developed initially to compare vaccination strategies against AI but it has since been also applied on ND. Initial applications were conducted to compare vaccination strategies using vaccines applied at the hatchery level versus vaccines applied at the farm level. New applications looked at other types of vaccination strategies, for example strategies applied on different geographic areas. The objective of this work was to compare different vaccination strategies against AI or ND between countries with various epidemiological context (enzootic and epizootic), types of vaccination (vaccine application based, geographically based) and production context (indoor or free-range, large or small farms, species produced, etc.). We analysed applications of the EVACS tool conducted between 2015 and 2022 in several countries all around the word: Egypt, Bangladesh, Indonesia, Vietnam, Tunisia and France. EVACS is a simulation tool developed in R® which allows to: model the animal production network using a social network analysis method; identify and characterise different vaccination strategies; evaluate vaccination performances using a stochastic model (vaccination coverage; immunity levels; duration of immunity levels; spatial distribution of immunity levels); analyse the cost-benefit of the strategies to identify the most efficient one. The tool is applied in a participatory approach with a validation of the production network and the vaccination strategies by stakeholders of the studied poultry production sector and the results are discuss and validated with them. This analysis showed that the EVACS tool provides informative elements for decision makers to choose between different vaccination strategies adapted to each context. The tool appears to be very informative in the comparison of vaccination strategies using hatchery application versus farm application as the tool is based on a network analysis including hatcheries. In Indonesia and Bangladesh, the tool showed that vaccination strategies against AI and ND using hatchery vaccines were more effective and offer a best cost-benefit ratio than strategies based on farm vaccines. The tool can provide elements to compare vaccination strategies based on geographic level. In France, vaccination strategies against AI excluding broiler production offered a vaccination immunity level lower than 60% of the entire population, while strategies including at least part of the broiler production provided immunity level above this threshold. In this country, the tool informed on the percentage of birds to be vaccinated by species and production area in order to reach an immunity level above 60% of the population in higher risk regions. Nonetheless, as the tool does not yet include any differential geographical transmission risk evaluation, its implementation to compare geographical based vaccination strategies is limited. In all countries the application of EVACS has been useful at various levels. In some countries the tool helped decision makers to validate vaccination strategies against AI or ND through vaccine authorization, targeted populations for vaccination or selection of vaccine application. In others, EVACS informed poultry production stakeholders about vaccination options within their commercial production network. These applications have been conducted within a public-private partnership and highlighted the importance of this type of collaboration to have a better understanding of the needs of farmers, poultry production stakeholders and decision makers and to produce adapted vaccination strategies.

Auteurs et affiliations

• Hautefeuille Claire, CIRAD-BIOS-UMR ASTRE (FRA)
• Dauphin Gwenaelle, CEVA Santé animale (FRA)
• Peyre Marie-Isabelle, CIRAD-BIOS-UMR ASTRE (FRA) ORCID: 0000-0002-0887-3418

Source : Cirad-Agritrop (https://agritrop.cirad.fr/612052/)

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