“They’ll be testing to see if the H5N1 virus in the BC teen is binding the sialic acid-α2,6-galactose (SAα2,6Gal) receptor with high affinity. If so, the leap necessary for efficient human to human has been made.

In order for efficient H-H transmission of avian viruses there needs to be a change from preferential recognition by the virus hemagglutinin of α2-3-sialyl-galactose-terminating host cell receptors, predominant in avian respiratory and gastrointestinal epithelia, to those terminating in α2-6-sialyl-galactose, which predominate in the human upper respiratory tract.”