› added 4 years ago
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TIL that H1N1, the influenza strain that caused the 1918 flu pandemic, survived another 40+ years as a seasonal flu bug. It was finally “extinguished” by another flu virus, H2N2, in the 1957 flu pandemic. Even so, a “new” H1N1 emerged 50 years later to cause the 2009 “swine flu” pandemic.