In a common event that's always active, check if the actor has the state, and if their current spirite is the correct sprite, If the first is yes, but the second is no, it changes the sprit.
Then have it check if the actor doesn't have the state, but has the sprite. If they don't have the state but have the sprite, it changes them back
Their should probably be like a 5 frame wait for each check. It would need to be parellel process and turned on by an auto-event early in the game or at the first possible place they can get vampirism