Avian influenza: past, present and future

Avian influenza is not a new disease, but the emergence of high pathogenicity avian influenza (HPAI) viruses of the A/Goose/Guangdong/1/96 lineage (GsGD) has necessitated fundamental changes to prevention and control of this disease. It is no longer just an avian disease but capable of causing severe disease in humans and is considered a potential human pandemic threat requiring One Health approaches. GsGD HPAI viruses also developed the capacity to be carried across and between continents by migratory birds. With persistence of the current A(H5N1) clade 2.3.4.4b viruses in wild birds, enhanced measures to prevent and control infection will be needed. In most countries infection in poultry can be eliminated, although questions will continue about sustainability of repeated stamping out. Systematic preventive vaccination should be seriously considered as a method for reducing outbreaks. HPAI will not be eliminated from countries where GsGD viruses remain enzootic until major changes are made to the way poultry are reared and sold, vaccination is improved and other factors that inhibit reporting and response are overcome. While current attention is mainly focused on GsGD HPAI, control of other low pathogenicity avian influenza viruses also requires attention, including properly matched vaccines.