Final answer:
The Spanish Flu pandemic during the end of WW1 resulted in an estimated 500 million individuals becoming sick worldwide, with 40 to 50 million deaths.
Step-by-step explanation:
The influenza pandemic around the end of World War I, commonly referred to as the Spanish Flu, was the most lethal in documented history. An estimated 500 million individuals worldwide fell victim to the disease, leading to between 40 to 50 million deaths, a casualty rate higher than the war itself. This disease is believed to have originated from the United States, facilitated by the conditions of the World War I such as crowding and rapid mobilization of troops. The emergence of a new strain of virus thought to have been a result of recombination between avian and human flus caused widespread fear and panic, exacerbating the post-war trauma.
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