Although California dairy farmers anticipated a bird flu mortality rate of less than 2% ... hypotheses — including one that posits people who were exposed to the H1N1 swine flu outbreak in 2009 may have acquired some immunity to the “N1” part ...

H5N1 avian influenza, more commonly known as bird flu, has infected more than 100 million birds in the U.S. and almost 500 dairy cattle herds across 15 states. The virus has popped up in mammals including elephant seals,

Initial testing had indicated the teenager’s infection was from bird flu and was confirmed in further testing, the Public Health Agency of Canada said in a statement. The teen has been hospitalized in Vancouver since Friday and was reported in critical condition on Tuesday.