Core Points - The first confirmed human infection of the H5N5 strain of avian influenza has occurred in Washington state, marking a significant event in public health [1] - The patient had underlying medical conditions and was in contact with a backyard flock of mixed domestic birds [2] - Investigators found avian influenza in the environment surrounding the household birds, indicating likely exposure through contact with domestic poultry or wild birds [3] - Health officials report that the overall risk to the community remains low, with no evidence of human-to-human transmission [4] - Monitoring is in place for individuals who had close contact with the patient and those who interacted with the backyard flock [5] - Human bird flu cases attract attention from investors in vaccine and antiviral companies, potentially impacting stock movements for firms like Pfizer and Moderna [6]