I would tend to disagree. In the middle ages, populations were not mobile...People were born, lived and died, within a few miles...there was haredly any travel between villages. That's how the plague ended..it burned itself out...When everyone in a village was dead, it died off..
Most people stayed put in the Middle Ages, true, but there were always small groups who traveled: tinkers, pilgrims, merchants, mendicant friars, messengers, and so forth. It was enough to spread the plague.
The evidence suggests that when regions were attacked by recurrences of the plague, mortality decreased.
The same was true of syphillis, which killed people rapidly in the earliest outbreaks around 1492 but became less deadly, or at least much slower to act, as time went on.
Apparently the Bubonic plague started in China and was spread by trade to Europe.