"Yes," Frank answers without hesitation. He's afraid of that above all else. And if it's not Kilgrave then it will someone like him. Someone who can do what he does.

"She was given a version of the vaccine. At least, we think that's what it is. Could you test it?" Before they poison themselves etc. It should be easier to make more vaccine if it's real, right? Maybe. He only really cares about Jess and Kam being immune anyway.