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.

Genetic analysis of H5N1 bird flu viruses from a severely ill patient in Louisiana revealed multiple mutations that may enhance the virus’s ability to bind to human upper airway cells, the Centers for Disease Control and Prevention (CDC) reported on Thursday.