Good news.... and we didn't even know about it. Fascinating read.
.....In its day, the disease killed between 30 million and 50 million people — about 1 of every 3 Europeans. It came at the worst possible time — when the climate was suddenly getting colder, the world was in the midst of a long war and horrible famine, and people were moving into closer quarters where the disease could infect them and spread easily, scientists say. And it was likely the first time this particular disease had struck humans, attacking people without any innate protection.
"It was literally like the four horseman of the apocalypse that rained on Europe," said study lead author Johannes Krause of the University of Tubingen in Germany. "People literally thought it was the end of the world."
In devastating the population, it changed the human immune system, basically wiping out people who couldn't deal with the disease and leaving the stronger to survive, said study co-author Hendrik Poinar of McMaster University in Ontario......