Most human cases of bird flu in North America have been mild, a fact that’s underscored by a new study of the first 46 confirmed human H5N1 infections in the United States this year. But the case of an ill Canadian teen stands out because of its severity and because the source of exposure remains a mystery.

A 13-year-old Canadian girl recovered after being hospitalized in critical condition with H5N1 avian influenza, researchers reported. The girl was hospitalized on Nov. 7 and transferred to BC Children's Hospital the next day,

In 2024, at least 66 human cases of bird flu have been reported in the United States, each one raising the risk of another pandemic like COVID-19. So far, most cases have been described as “mild,” which means they weren't hospitalized.