The Gordon Memorial Lecture: A paradigm shift in high pathogenicity avian influenza and perspectives for the future

Since 2020, H5 high pathogenicity avian influenza (HPAI) viruses of clade 2.3.4.4b have spread rapidly to all continents except Oceania. This panzootic presents an unprecedented threat to global poultry health, with severe uncertainties as to when it will peak or resolve. The complex epidemiology across multiple ecosystems creates unparallelled challenges following the spread of virus to and within multiple orders of wild birds.2. Sustained infection in numerous species of wild mammals, together with a substantial outbreak in US dairy cattle, increases the animal health threat and elevates risk for increased zoonotic infections. In developed commercial production systems, biosecurity can still be deficient and, if not addressed, can exacerbate the problem further.3. The virus is currently phenotypically stable but continually evolving at the genetic level and these changes need continual tracking to understand future risk and adaptive interventions. This disease not only threatens poultry production and food security worldwide but has a significant impact on biodiversity and improved tracking and knowledge of ecology in wild populations is required.4. Vaccination is a single tool that has potential utility as part of a holistic control plan. In some countries, vaccination has been used successfully to control the disease, but global success remains limited. Improved use of best practice, tailored to practical use in multiple production systems is required for future prevention and control.