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.

The avian flu virus isolated from a hospitalized teenager in Vancouver has mutations in key areas that could help the virus spread more easily in humans, scientists say. There is no indication that ...

Scientists have discovered that H5N1, the strain of highly pathogenic avian influenza virus currently spreading in U.S. dairy cows, only needs a single mutation to readily latch on to human cells ...