Struggling to find clarity on endemicity/epidemicity. Many references say it's all about rate of infection.…

Struggling to find clarity on endemicity/epidemicity. Many references say it's all about rate of infection. And/or they say it's also about being self-sustaining in a geographical area, for endemicity, but epidemics can be geographically constrained and prolonged too? Anybody? https://t.co/oV94yaskAS