[Excerpts from two presentations during the 2026 annual meeting of the American Association of Avian Pathologists]
David Swayne, Birdflu Veterinarian LLC, USA, noted that the expanded use of vaccination for the prevention and control of high pathogenicity avian influenza (HPAI) was strongly emphasized in 2025. The release of the Global Strategy for the Prevention and Control of High Pathogenicity Avian Influenza (2024–2033) by the Food and Agriculture Organization of the United Nations (FAO) and the World Organization for Animal Health (WOAH) established a global framework and collective blueprint for action. This emphasis was further reinforced by the FAO meeting Tackling HPAI Together, held in September 2025 in Brazil, which highlighted vaccination as a critical component of effective HPAI prevention and control.
Substantial progress toward broader acceptance of vaccination as an HPAI control tool was achieved in 2025. Key developments included the release of USDA Grand Challenge funding supporting new HPAI vaccine projects; approval of HPAI vaccination in the Philippines and South Africa, with vaccination plans under development and implementation; and the release of a targeted vaccination framework for laying hens in the United States by United Egg Producers (UEP), subsequently endorsed and expanded to turkeys by the National Turkey Federation.
Additional advances included the development of emergency vaccination plans for ducks and geese in Hungary; ongoing work in Italy on vaccination strategies for layers and turkeys; release of a proposed turkey vaccination plan in the United Kingdom; completion of a laying hen vaccination field trial in the Netherlands; and completion of three years of duck vaccination in France, demonstrating reduced infection in vaccinated populations.
H5N1 vaccination in South America
Silvana Gagliuffi and Eliana Icochea, Universidad Nacional Mayor de San Marcos, Lima, Peru, reviewed vaccination strategies against highly pathogenic avian influenza (HPAI) subtype H5N1, a major challenge for poultry production and global public health.
Since late 2022, H5N1 clade 2.3.4.4b has been detected in South America, causing high mortality in wild and commercial birds, along with isolated cases in marine mammals and humans. These outbreaks have revealed the limitations of relying solely on biosecurity and mass culling, reinforcing the need for vaccination programs as complementary and sustainable control tools.
Globally, authorized vaccines are mainly inactivated types (95.5%), applied in chickens, layers, turkeys, ducks, and geese. They induce strong humoral immunity but require periodic boosters. Vector vaccines, such as recombinant turkey herpesvirus (rHVT), represent 4.5% of the market and are notable for eliciting both cellular and humoral responses while avoiding interference with maternal antibodies.
In South America, both approaches are used together, while new platforms (RNA, DNA, recombinant proteins) are emerging under the DIVA strategy (Differentiating Infected from Vaccinated Animals), which allows distinction between vaccinated and infected birds and strengthens epidemiological surveillance.
Administration routes include hatchery protocols (in ovo and subcutaneous at hatch) and farm-level applications (subcutaneous and intramuscular). In ovo delivery ensures early, homogeneous immunity, while subcutaneous injection at the farm level is most common in breeders and laying hens. Proper application is essential to maximize efficacy and reduce immunological failure. Serological monitoring validates vaccine response through hemagglutination/inhibition, and indirect ELISA. Viral isolation, though slower, remains the diagnostic gold standard.