I tend to the opposite problem, sims being potential victims simply because of their existance. To improve the safety probability I follow the advice given on forums ages ago: no communication with known vampires, no speking of vampire subjects or research in any form, keep all doors locked at night, plant garlic by walkways. It takes some vampire knowledge levells to make the wreaths & garlands, but I believe they are in b/b via the cheat for hidden stuff. Have found that Vlad really likes the water slide so that is part of the defense system now. As a last resort, there is the instant become vampire cheat when attack is coming, to be reversed once threat over.
