The fate of a Canadian teenager who was infected with H5N1 bird flu in early November, and subsequently admitted to an intensive care unit, has finally been revealed: She has fully recovered.But genetic analysis of the virus that infected her body showed ominous mutations that researchers suggest potentially allowed it to target human cells more easily and cause severe disease — a development the study authors called "worrisome.

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.

The first severe case of H5N1 bird flu was confirmed in Louisiana. Here is a map of other states that have been affected.