Consideration for Avian Influenza Vaccination in the World

Abstract

Global spread of high pathogenicity avian influenza viruses (HPAIVs) in bird population and its infection in human are at high concern. Since 2020, the HPAIV infection has been continuously reported in Europe even in summer, and spread to North American and African countries. Finally, it eventually reached to South American countries where no HPAIV infections had been reported. Given the huge concern to global HPAIV spread, the possibility of vaccine implementation has been discussed at global level though the basic control measures against HPAIV infection in poultry is detection and culling. World Organization for Animal Health (WOAH) agreed for use of avian influenza vaccine when HPAIV control by culling is too difficult. For the preparedness of emerging situation in Japan, the inactivated vaccine against HPAIV infection for emergency use had been developed using the non-pathogenic avian influenza viruses. The vaccinated chickens were survived from HPAIV challenge but the vaccine did not protect them from infection of challenge virus, posing the possibility that the silent spread of contagious viruses should be sustained in the vaccinated poultry flock. Even understanding the limitations of current HPAIV vaccines, several member states had considered for preventive vaccination in poultry. In 2023, French government decided to start the vaccination to domestic duck, but only rare species, to protect them after careful assessment and discussion in this issue. Global society has considered vaccination positively to decrease the HPAIV infection and the trade damage by it, which was also agreed with WOAH. Nevertheless, the basic control measures against HPAIV had not changed at all, and more intensive measures, active surveillance and antigenicity investments, are required to start vaccination in poultry flock.