How are Hep V vamps killing so many people who are an toàn, két an toàn 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, hoặc air supply. They aren't burning houses down. Why wouldn't people be an toàn, két an toàn in their homes until sun up?