Disease movies are the scariest movies

I never found horror movies too scary, except horror movies about diseases, like REC, The Bay, Contagion, 25 days later, etc 

The reason I personally find it scary is that its not something you can be certain to prevent, hazmat suits, mask's, quarantines, doesnt matter, one small mistake, rip, anything can give you it. 

Whats scarier is that EVERYONE is a target no matter what unless you're immune which is certainly unlikely in these types of movies, it doesnt even need zombies for it to be scary the concept of a microscopic being that can multiply is horrific enough, which is why I love it so much, and why I love zombie media aswell.