Avian influenza, typically transmitted by birds, has sparked growing concerns due to its increased detection among mammals, which share closer biological similarities with humans. The emergence of avian influenza A(H5N1) in mammals raises fears of potential adaptation to infect humans more readily.

Since 2020, a variant of avian influenza A(H5N1) belonging to the H5 2.3.4.4b clade has been responsible for a significant number of deaths in wild birds and poultry across Africa, Asia, and Europe. The virus extended its reach to North America in 2021, followed by Central and South America in 2022. In 2023, numerous countries, particularly in the Americas, reported outbreaks.

Mass die-off events among wild birds, attributed to the A(H5N1) clade 2.3.4.4b strain, have been documented, alongside a rising number of cases among terrestrial and aquatic mammals. These cases, which include pets, have led to instances of morbidity and mortality, heightening concerns about the potential for further spread and adaptation of the virus.