How are Hep V vamps killing so many people who are sicuro, cassetta di sicurezza in their homes?

Question: assuming hep-v vamps need an invitation before entering a human's house, how are the committing mass murder? From the looks of it they aren't sabotaging food, water, o air supply. They aren't burning houses down. Why wouldn't people be sicuro, cassetta di sicurezza in their homes until sun up?