Have you ever wondered why you have to get a flu shot every year, but some vaccines are one-and-done? It all has to do with how and how fast viruses evolve - and that depends on mutation rates.

A 13-year-old girl in British Columbia who was hospitalized with bird flu for several weeks late last year harbored a mutated version of the virus, according to a report published this week in the New ...

As the seasonal flu picks up, there are even more opportunities for the bird flu to acquire mutations as the different influenza viruses mix. A 13-year-old girl in British Columbia who was ...