I'm asking because I been working on what is called the Spanish Flu. It was a strange pandemic, mostly unknown to the public. People know mush more about the Black Death than they do about the worst pandemic in our history. The pathogen was the H1N1 virus, a flu virus. There are strange things about the disease. It killed a lot of people between 20-35 years old. H-strain viruses and corona viruses don't normally do that. The flu pandemic seems to have three epicenters, that is also unusual. One in Kansas, one in northern France and one in southeast Asia. There was an outbreak of a flu epidemic in France among British/Commonwealth soldiers in 1916-1917, which seem to have been a swine flu type A virus. But something happened in the summer of 1918, I think I know what happened. These three different type of H-viruses meet and exchange genes and mutate to a more lethal type. The Spanish flu killed about 50-100 million people world wide and mostly those in their prime of their lives. Why did it do that and what can we learn from it? The virus attacked the lungs and caused their immune system to go in an overdrive so basically. Their own defense killed them. The reason was, these generations had never been exposed to similar flu viruses. The war caused the recipe for a disaster when huge amount of people were moving around in the world. Now we can move between continent in hours instead of weeks. if or rather when a similar pathogen mutate and became equally lethal as the Spanish flu, we will have a problem. There are two different H viruses that may can cause a huge problem. The H5 and the H7 strains, which are both swine flu and avian flu viruses (most diseases are zoonotic, they transmit from animals to humans) and these two can be dangerous when they have mortality rate of 75%, the Spanish flu had a mortality rate of 20%. The corona virus now isn't a major concern, unless it mutate and the risk for a mutation increases a lot for every person getting infected.