Canada

And what might those preparations look like?

All preparations for disaster look like a cost-benefit analysis and reasonable actions taken to mitigate those disasters. Sometimes, that means relying on collective tools - laws, incentives, etc., which can be easier sometimes, if it works. Other times, it's internal planning, or physical training, or avoidance of problematic situations.

Another big aspect of preparation that people can do is genuinely coming to terms with the existence of whatever particular problem they're facing. "Radical acceptance", so to speak, though one needs to know the difference between accepting and submitting. When you can't accept something, you end up blindsided by it, shocked and appalled that it can happen to you, or that humans can't just talk it through, or whatever. When you can, you generally see it coming a ways away, and can address it before it becomes an issue for you, instead of thinking "I shouldn't have to deal with this," or "but humanity is better than that, and we can just talk it through."

But, that kind of preparation takes a lot of world-view shifting, and skill-building in processing fears, and for people who don't really have evidence of the benefit, it's hard to pay the cost in time and effort on personal growth in that area. C'est la vie.

A vaccine is never 100% effective. [...]

Indeed. However, there must be a line for what a collective can or cannot reasonably impose on an individual. And, whether you like it or not, the physical body is a real boundary, and granting a collective governing body power over what you put into or take out of your own body is a larger issue than vaccination, and people will utilize that power against you, not just for you.

This is true enough that as soon as the Democrats started pushing for mandatory vaccinations during covid, I knew and stated that the cost would be abortion. ..and that's exactly what was lost, in many states.

Any power you give the government, will be used all of the ways it can be used, depending on the party in power and the moral fads that the culture goes through - and as you can see with trump and the underlying expressions going on there, these fads aren't always going to be in your favor.

Although there are some areas that are morally more stable, any area that doesn't have fairly universal support will go through this dynamic of flipping what side gets to utilize that power, and in what way it is used.

Case in point:

The Republicans centralized power in the presidency with the USA Patriot act. The Democrats, in power when it expired, renewed it, rather than letting it drop, or (even better) making an act to prevent that centralization of power. Obama utilized that power to great effect, including to fulfill the reason for it's temporary existence. ..and then he renewed it, when it was no longer needed, and after it had expired, because of lack of ability to consider that maybe power isn't always a good thing, and sometimes you need to let go for things to work right.

..and the dems can't keep hold of that power. ..and now that power is Trump's and the reps in general, until their fire burns out.

As a side note: The irony is that maybe Trump, if he thinks the dems will win, might nerf presidential powers out of spite - which would be great, if it sticks.