> What’s even more remarkable about the 1918 flu, say infectious disease experts, is that it never really went away. After infecting an estimated 500 million people worldwide in 1918 and 1919 (a third of the global population), the H1N1 strain that caused the Spanish flu receded into the background and stuck around as the regular seasonal flu.
> But every so often, direct descendants of the 1918 flu combined with bird flu or swine flu to create powerful new pandemic strains, which is exactly what happened in 1957, 1968 and 2009. Those later flu outbreaks, all created in part by the 1918 virus, claimed millions of additional lives, earning the 1918 flu the odious title of “the mother of all pandemics.”
[1] https://www.google.com/amp/s/www.history.com/.amp/news/1918-...
This isn't quite true. All epidemics come to an end eventually, vaccines or no vaccines. There were no vaccines to end the 1918 flu epidemic, but that one too died out just like all the ones before it in a few years' time. At a far greater cost to human life, of course, but we "got out" of it.