Thread by @apsmunro

Is the immune system like a muscle? 🤔

Yes actually, in many ways it is 💪

EXCEPT it's not one big "general" muscle

You have specific muscles for each different pathogen, and each of them is a bit different in how quickly/easily it gets stronger or weaker🏋️‍♂️

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For some bugs, once you've fought it once, your muscles are so strong against it they may never need another work out to fend it off (e.g. measles, smallpox)

For others, they get weak quite quickly, but get stronger again each time you fight it (e.g. RSV, Covid)

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The good news is, for many bugs you don't need to fight them at all to get stronger

That's what going to the gym is for 🏋️‍♂️

Vaccination! 💉

Your immune system gets practice fighting the bug, but without risk of you getting injured by it

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Does this mean you should go looking for fights?

No!

But it does mean if you (or many people) haven't fought a particular bug for a long time, your immune system might not be as ready to fight it off so quickly

Best bet is to head to the gym if you can

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Usual disclaimer that all our models of immunology are huge simplifications of an extraordinarily complex system we don't fully understand and there are always caveats etc

But as a simple model, the immune system as lots of muscles is actually surprisingly good

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