Genetic analysis of H5N1 bird flu virus that infected a Canadian teenager shows 'worrisome' mutations, new studies reveal.

So far, the H5N1 virus isn't transmitted between people — but the CDC has found a mutation in a human case "concerning." ...

The call to authorize a vaccine comes after the CDC announced that a person in Louisiana was hospitalized with the country's first known case of severe illness caused by the virus earlier this month.

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 ...