Dystopia/ Science Fiction - lab in America creates vampire-like creatures the main character is a girl who is a test subject but retains her thinking abilities

[Naeva]

It's not a new book it's rather long and the cover is grey with the face of a girl with hair covering much of her face. It's a pretty well-known book I think and if you don't have time to read everything just the first paragraph will hopefully be enough to jog your memory?
SPOILERS AHEAD
A lab in America is conducting experiments on people (they use people from prisons). There is a guy whose job is to convince said prisoners that only a few experiments will be done on them and it's better than whatevers waiting in prison. Then for some reason he has to take this little girl to the facility. I'm pretty sure he tries to help her escape but his partner spots him. There's a nun somewhere in the middle as well. She gets turned into a vampire thing but she doesn't go completely crazy or be full of bloodlust or anything. The other vampires in the facility (who actually have this hive-mind) thing escape and in the chaos the nun and the other guy help her escape. Nun dies in the process.
The other guy takes care of her in some remote house while pretty much the entire world is torn apart by said vampires. Guy eventually dies. The story shifts to this safe place where people stay but they're running out of electricity to keep the lights on. My memory's a bit hazy over there but I remember that eventually some of the people from there run away and I think they meet the other the girl somewhere in the middle? Anyway at the end they kill this vampire that was leading some of the others and also everyone else in the safe place dies.

[Searabbits]

Possibly - The Passage? Has vampires, a child, prison experiments at least - according to the wiki page (I haven't read the book myself).

[Andy Phillips]

I second 'The Passage'. The TV series is a very close match to the first part of the description and the book cover matches on the issue I have (but haven't read yet).