The Spanish flu pandemic took place from 1918 to about 1920, with its deadliest wave in the fall of 1918.

Quick Scoop: When Was the Spanish Flu?

  • Most historians date the start of the Spanish flu pandemic to early 1918, with widely cited first major outbreaks in March 1918.
  • The pandemic unfolded in multiple waves: a milder spring 1918 wave, a highly lethal fall 1918 wave, and a further wave in winter 1918–1919, with some experts extending its impact into 1920.
  • Overall, the Spanish flu era is usually described as the 1918–1920 influenza pandemic, one of the deadliest disease events in modern history.

In short: when people ask “when was the Spanish flu,” they are almost always referring to the global influenza pandemic that raged mainly between 1918 and 1920.

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