looking for title

universe has like a “rage virus” and makes people attack random people, and a way to tell who’s afflicted is with flashlights. there’s emergency flashlight kits in neighbourhoods. i remember it being pretty funny and a little stupid. one storyline they had to protect a couple with a baby, another storyline they had to find somebody’s grandpa who supposedly had the rage virus but also dementia. mc is good with a gun but doesn’t like using them some because of some kind of trauma. might not be rage virus specifically, but it was like a mystery infection that would make people rage and the mc and ml work as basically a clean up crew for them :p