I have an 80yo friend who lived though both of those pandemics and says that the 1957 one was terrifying in the UK. It hit nursing staff very quickly and hard, many hospitals were running below half-staff. It was the first pandemic of the air-travel era and spread like wildfire.

But until this latest pandemic arose he hadn't even mentioned his experience, it was just considered part of life. And unless you know to look for it, it's barely mentioned in modern history.