community transmission

This belongs in a set of types of virus transmission which usually balances the giver to the receiver, as in person-to-person transmission. You can have hotspot-to-hotspot transmission, and hospital-to-hospital transmission. But the one that is most feared is the community transmission because this is the one that cannot be traced. It is impossible to know which person in the community has handed on the virus to which other person. All you know is that there is an explosion of cases.