Key points
Outbreaks of avian influenza A(H5N1) clade 2.3.4.4b viruses continue to be widespread among birds and poultry in many parts of the world, with transmission to mammals including humans in some countries and dairy cattle in the United States.

These viruses are considered to have pandemic potential owing to their ability to infect and spread among mammals, their historically high mortality rate in humans, and the general lack of immunity in the human population.

Although the current risk of infection for the public remains low, Health Canada recently authorized an H5N1 influenza vaccine that may benefit certain people with increased risk of exposure to the virus, such as those who work with the virus in laboratory settings or are involved in culling infected poultry, as an added layer of protection in addition to other preventive measures.

Ongoing monitoring of the immune response to H5 influenza vaccines against circulating avian influenza strains will help to inform whether updated vaccines are needed.