In a lot of ways this book felt more like a zombie novel than a vampire novel. Vampirism is a disease passed through a bite. As with zombies,(because a rouge vampire started the spread) the virus grows at an exponential rate and will wipe out humans in a short period of time. (I always wonder, did these writers ever play Pandemic? It's really hard to infect and kill everyone on the planet. I'm just saying). The dead return home and as the disease progresses they become mindless horrors whose existence comes down to a craving for blood. Only really old vampires seem to retain any cognitive ability.
And, of course, our protagonists are trying to stop the outbreak.