In 1918, much of the world was impacted by a devastating influenza pandemic. Commonly referred to as the Spanish Flu epidemic, this event lasted for just over two years. During this time, it claimed a staggering fifty to one hundred million lives. As a result of this huge death toll, this flu epidemic was the deadliest natural disaster in human history. In addition to the huge death toll that this epidemic inflicted on the world, during this period of time, over five hundred million people were actually infected by the virus, which was one third of the entire global population at the time.

One of the strangest facts about this flu epidemic is that while children and middle-aged adults are normally impacted the most by the standard influenza virus, in the case of the Spanish Flu, it was actually young adults who were most likely to be killed by the virus. Scientists have discovered that the reason for this is that this type of influenza virus kills by a “cytokine storm,” which means that it puts the immune system into overdrive. Because young adults have a stronger immune system than children and middle-aged adults, it was easier for the virus to throw their immune systems into overdrive.