They constantly change. so what you have in any flu population, you're always having a little bit of change, so may be the great majority of them have those two dots, but may be every now and then one of them has one dot, one of them has 3 dots, and maybe that is just a random mutation, this just randomly happened, maybe one in every - I'll make up a number - one in every million of these viruses has this only one dot instead of two dots, but what's gonna happen as soon as the human immune system gets used to attacking the virus with the two red dots, well then this guy isn't gonna have to compete with the other virus capsules for infecting people he's going to have people's DNA all to himself.