Jubilee was infected with a purpose, to lure a specific male unnamed mutant to them so that they could turn him and use him to turn the rest of the mutants. So that the mutants can be used to bolster the ranks of the Vampire race and make them unstoppable.
Who is he? Well, he’s not named, but I’ll give you a hint as to who I’m guessing.
Seems like a good guess, right?