Canadian teenager in critical condition with presumptive bird flu as U.S. official warns the virus 'seems to be gearing up for wider impact' Health officials were struggling to answer a broader and potentially worrisome question: how the infection occurred. Carolyn Barber Fortune

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“This case is very concerning for a number of reasons,” says Rick Bright, an American immunologist and vaccine researcher and a U.S. government health official from 2016 to 2020. “It’s in an otherwise healthy teenager. Like a similar case in Missouri, there’s no clear source for infection and no direct farm connection.”

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