The Great Black Death

Reality
The Black Death was one of the deadliest pandemics in human history, peaking in Europe between 1347 and 1351. It is widely thought to have been caused by a bacterium named Yersinia pestis

The origins of the plague are disputed among scholars. Some historians believe the pandemic began in China or Central Asia (one such location is lake Issyk Kul) in the lungs of the bobac variety of marmot, spreading to fleas, to rats, and eventually to humans. In the late 1320s or 1330s, and during the next years merchants and soldiers carried it over the caravan routes until in 1346 it reached the Crimea in South Eastern Europe. Other scholars believe the plague was endemic in that area. In either case, from Crimea the plague spread to Western Europe and North Africa during the 1340s. The total number of deaths worldwide is estimated at 75 million people, approximately 25–50 million of which occurred in Europe.

The Black Death is estimated to have killed 30% to 60% of Europe's population. It may have reduced the world's population from an estimated 450 million to between 350 and 375 million in 1400

POD : the black death is much more virrulent than in reality, killing between 60% and 85% of Europe's population and killing over 200 million worldwide.