Evaluation of vaccination strategies against highly pathogenic avian influenza H5 in Spanish poultry production: application of the EVACS tool

Source Agritrop Cirad (https://agritrop.cirad.fr/612056/)

International audience

English. The 2021-23 period marked a turning point in the epidemiology of highly pathogenic avian influenza (HPAI) H5 viruses. Europe and the world have been facing the largest number of HPAI H5 outbreaks ever. Spain was no exception and reported seven poultry outbreaks and 113 wild bird cases in 2022-23. Given the disease situation, EU members are now allowed to authorize vaccination in their country. France is the first country that has applied vaccination (from the 1st Oct 23) but considering the evolution of the epidemic situation, other European countries may also start vaccinating. The aim of this study was to evaluate and compare potential HPAI H5 vaccination strategies adapted to the Spanish poultry industry of broilers, layers, turkeys and ducks. To do so, the EVACS tool was applied and five different vaccination scenarios against HPAI H5 compared, using a recombinant vaccine at the hatchery level and/or an inactivated vaccine at the farm level. This simulation tool, developed in R®, consists of five modules: model the production network using a social network analysis method; identify and characterise different vaccination strategies; evaluate vaccination performances using a stochastic model (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 results of this study showed that for the vaccination scenario targeting duck, turkey and layer production, the immunity level of the population concerned by vaccination was above 60% for the scenario based on hatchery vaccination and below for the scenario based on farm vaccination. With the same scenario, the geographical distribution highlighted that this immunity level reported to the entire poultry population was above 60% for a third of the provinces using hatchery vaccination while this level was lower for all of them using farm vaccination. Vaccination strategies were efficient for turkey and layer production with hatchery vaccination, when the surveillance cost was not considered. This work can be used to design efficient vaccination strategies as recommended by EFSA. It has 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.