Amid heightened concern regarding an avian flu pandemic, mutations were identified that would allow strains of H5N1 and H7N9 to make the jump from an avian to human host. H5N1 and H7N9 have thus far only been able to transmit from birds to humans. However, an evolved strain exhibiting outlined mutations would gain the ability of human-to-human transmission. These findings have implications for both vaccine design as well as global monitoring and prevention of a possible pandemic.