Emerging H5N1 Mutations and Human Infection Risks

• H5N1, a highly pathogenic avian influenza virus, has been spreading globally since late 2020.

• Recent human cases in British Columbia, Canada, and California raise concerns about the virus’s adaptability and potential mutations facilitating human-to-human transmission.

• In November 2024, a teenager from Fraser Health, British Columbia, was diagnosed with H5N1, the first domestically acquired case in Canada.

• Genomic sequencing revealed the virus belonged to the 2.3.4.4b clade, genotype D1.1.

• The PB2-E627K mutation, linked to faster replication in human cells and greater illness severity, likely emerged during the infection.

• The U.S. CDC confirmed the first human case of H5N1 avian inuenza in a child from Alameda County, California, with no evidence of human-to-human transmission.