In a very short period of time the Bubonic Plaque killed an estimated 50 million people, 30% to 50% of the population of Europe at that time. At the time, the mortality rate was as high as 90% of those infected.

Nowadays it can easily be treated with antibiotics, mortality is less than 10%. But it is not gone, there are still about 650 deaths per year from it, worldwide.

You can see from the diagram that the plague came in through Turkey and in a space of about four years engulfed Europe and spread up to Scandinavia.

By today’s standards this is actually pretty slow, but remember they were all traveling by horseback at the time, and the average person rarely went more than a few miles from where they were born in their whole lifetime.

Covid spread rapidly because our transport system takes people around the world on a routine basis.