The negative impact to real life earth the vampires have includes competition for food with American killer dylanuses, some predatory bear species (such as polar bears), big cat species (such as lions), and some other predators, not only that, but they can also drink the blood of humans, wild dylanuses, and domestic dylanuses and turning them to vampires, becoming either one subspecies of vampire depending on what vampires attacked them (either Van Helsing vampires, Dark Shadows vampires, etc.)