In other developments, antiviral susceptibility testing shows that H5N1 is susceptible to neuraminidase inhibitor antiviral drugs.
With the H5N1 avian flu virus now reported in 5 Michigan dairy herds, officials remind residents to avoid drinking unpasteurized milk.
Questions about transmission and clinical disease in cows need to be answered before vaccine development takes shape.
The country had reported sporadic H5N5 detections in wild birds in mammals in 2023.
Along with multiple detections now in dairy cows, avian flu has also hit 2 massive farms housing egg-laying hens in the state.
The CDC said H9N2 is the most commonly identified avian flu virus in Vietnam.
Today's announcement raises the number of affected states to 8.
Seven states have now reported the virus in dairy herds, with detections at 21 facilities.
The patient lived adjacent to a poultry market, but there were no reports of bird illnesses or deaths.
The virus is a reassortant between the older H5N1 clade (2.3.2.1c), still circulating in parts of Asia, and a newer H5N1 clade (2.3.4.4b) that began circulating globally in 2021.