Here's a fascinating graph/chart

[PoindexterOglethorpe]

you can customize:

https://ourworldindata.org/spanish-flu-largest-influenza-pandemic-in-history

That link will come up with several countries already selected, but you can deselect all of them and then select whichever countries' life expectancies you want to look at.

The Spanish flu, because it so disproportionately killed young people in the prime of life, showed a strong and immediate impact on life expectancy, which in most countries seems to have very quickly bounced back to what it had been.

And if you scroll down you can get some other pretty interesting graphs and charts connected to influenza outbreaks.