Evaluation of commercial vaccines for efficacy and transmission control against the emergent H5N8 (clade 2.3.4.4b) avian influenza virus in Kazakhstan.

Highly pathogenic avian influenza H5N8 (clade 2.3.4.4b) has caused devastating poultry outbreaks globally, including in Kazakhstan, underscoring the need for vaccines that protect birds and curb virus transmission. We evaluated the efficacy of three commercial H5 vaccines and an experimental homologous H5N8 vaccine in chickens.