Why was the Spanish Influenza (flu), different than any other strand?

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2720273/

Explanation:Link explains perfectly

- "made the south's economy grow rapidly and a small effect that a lot of people don't know is that it made the more demand of slaves and cotton products. and also new states formed due to plantations growing in size."

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answer; /// i believe the three where,tutankhamun,hatshepsut and , im not sure,but maybe (ramses the great)