What does a "community transmission" mean?

Native speaker’s answer
Rebecca
In the context of infection disease, community transmission is when a disease is spread amongst people and the origin of the spread cannot be found (as in they are not known to have interacted with infected people or gone overseas where they could have been infected). Ex: Community transmission is one of the most common methods of COVID-19 transmission. Ex: Because community transmission is hard to track, it's difficult to control outbreaks.