One particularly crucial difference, I think, is public knowledge about diseases in general. During the plague, people were blaming every minority they could fi

One particularly crucial difference, I think, is public knowledge about diseases in general. During the plague, people were blaming every minority they could find. Can't really stop the spread of a disease if the extent of your knowledge of epidemiology is "God is punishing us because of you!". No "stay at home", no "wash your hands", no "don't cough on people". We may have a disease that'll be just as lethal, but this time nearly everyone in the world knows the basics about diseases. The global response to COVID hasn't been particularly heartening, but I think that's because it's in that "sweet spot" (more like sour spot...) range where the fatality rate is low enough that many people are not sufficiently cautious and allow it to spread widely, but high enough that it does kill a lot of people. If we someday have a much more serious disease, like with a black death fatality rate of 30%, I think it's likely to disappear very quickly unless it has an extremely long contagious incubation period. It might to do some serious damage at ground zero, but people will freak out and hide at home if a huge, visible percentage of people die. And this time, (I hope) people won't be running around pointing fingers and spreading the disease in the process.