Epidemiological Evolution, Vaccine Development, and Control Strategies of Highly Pathogenic Avian Influenza H5N1 Virus

Abstract

Since its initial identification in Guangdong, China, in 1996, the highly pathogenic avian influenza virus (HPAIV) H5N1 subtype has evolved into multiple genetic clades, with clade 2.3.4.4b emerging as the dominant strain. This clade demonstrates significant antigenic variability and continues to cause widespread outbreaks in poultry, as well as sporadic infections in humans worldwide. This review comprehensively outlines the epidemiological progression of H5N1, recent advancements in vaccine development, and comprehensive control measures. Viral evolution is primarily influenced by antigenic drift and reassortment, with specific amino acid mutations facilitating adaptation to mammalian hosts. Clade 2.3.4.4b, currently prevalent in Asia, Europe, and the Americas, exhibits considerable genetic diversity. Various vaccine platforms have been utilized, encompassing whole inactivated virus vaccines, live attenuated and vectored vaccines, virus-like particles (VLP) vaccines, subunit vaccines, and nucleic acid-based vaccines. However, widespread vaccine distribution encounters obstacles such as immune evasion, potential viral shedding, and differing international immunization regulations. Looking ahead, effective pandemic preparedness necessitates innovative vaccine strategies, strengthened global surveillance, improved biosecurity measures, and interdisciplinary cooperation to efficiently control transmission and mitigate pandemic threats.