There is some research that suggests that viruses like the flu are really actually kind of at the razor's edge when it comes to mutation. They're mutating so fast that if they mutated much faster they would actually develop a lot of harmful mutations that could slow them down and cripple them and eventually literally drive them extinct.
Today there are hundreds of millions of mobile devices, but you do have to know a bit about what each device is capable of doing in order to approach it as a developer.