# How did Spanish flu end?

**URL:** <https://boards.straightdope.com/t/how-did-spanish-flu-end/849988>\
**Category:** Factual Questions\
**Created:** [March 22, 2020, 12:05am UTC](https://boards.straightdope.com/t/how-did-spanish-flu-end/849988 "2020-03-22T00:05:35Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\
**Post date:** [March 22, 2020, 12:05am UTC](https://boards.straightdope.com/t/how-did-spanish-flu-end/849988/1 "2020-03-22T00:05:35Z")

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Specifically, how did it totally disappear? Why didn’t it just continue to infect newborns and pockets of people who had somehow escaped it? I recall hearing of an expedition to northern Norway to dig up frozen graves to try to find samples of the virus, so it seems to have vanished entirely. Or mutated to something less serious.

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**Author:** ![Ike\_Witt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ike_witt/32/283_2.png) [@Ike\_Witt](https://boards.straightdope.com/u/Ike_Witt)\
**Post date:** [March 22, 2020, 12:34am UTC](https://boards.straightdope.com/t/how-did-spanish-flu-end/849988/2 "2020-03-22T00:34:30Z")

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Interesting question. Cursory searching says it just died out after a second wave of illness. The reason why is not clear from what I see.

There were a few theories:

1. It mutated into a less lethal virus.
2. Those that were infected either died or developed immunity.
3. Cleanliness and sanitation stopped the spread.

I really hope that somebody who does know more about this will answer.

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**Author:** ![Ike\_Witt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ike_witt/32/283_2.png) [@Ike\_Witt](https://boards.straightdope.com/u/Ike_Witt)\
**Post date:** [March 22, 2020, 12:48am UTC](https://boards.straightdope.com/t/how-did-spanish-flu-end/849988/3 "2020-03-22T00:48:13Z")

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Duplicate post

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**Author:** ![asahi](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/asahi/32/8693_2.png) [@asahi](https://boards.straightdope.com/u/asahi)\
**Post date:** [March 22, 2020, 1:11am UTC](https://boards.straightdope.com/t/how-did-spanish-flu-end/849988/4 "2020-03-22T01:11:29Z")

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> [@Ike\_Witt](#):
>
> Interesting question. Cursory searching says it just died out after a second wave of illness. The reason why is not clear from what I see.
> 
> There were a few theories:
> 
> 1. It mutated into a less lethal virus.
> 2. Those that were infected either died or developed immunity.
> 3. Cleanliness and sanitation stopped the spread.
> 
> I really hope that somebody who does know more about this will answer.

That’s a pretty good synopsis. It was very successfully at two things: spreading and killing. It ran out of people to kill, and those who were not killed developed immunity to it.

Its ability to spread might be slightly overstated, owing to the fact that many of the things that people did in 1918-19 to spread the disease might not have occurred today. They were unable to identify the virus with their own eyes - the electron microscope wasn’t in use yet. Because of this, they could only fight the disease with hunches.