Why, categorically, should one be forcibly vaccinated in order to protect someone
else? Sure, it's the civilized thing to do, but why is the justification to
compel it?
(And yes, the "anti-vax" "movement" is disgusting - a fine example of the stupidity of crowds. Unfortunately, defending freedom often means defending scoundrels).
There's a similar argument around fire coverage. The common argument against a more libertarian approach to fire fighting is that if someone's house catches fire and is left to burn, then it will easily spread to neighbors, increasing their risk. And this the obvious physical reality, especially where things are dense.
But since those neighbors are the only concerned parties, then why (in principle) is that additional risk not theirs to bear and mitigate? It cannot cost any more than the neighbors splitting the cost of the fire protection on the unprotected building. Practically, the fire department would just pool that overhead across all customers.
Of course there is the issue of long term second-order effects - freeloading - since most likely if you didn't pay the fire department would still try to extinguish your house as quick as possible (possibly just busting it up a bit more in the process). But making coverage mandatory also ignores long term second-order effects when an organization does not have to be responsive to the people it serves (which is usually then handwaved away with the wisdom-of-crowds fallacy).
The root of the disagreement comes from different thinking about what society actually is. Is it a monolithic system we're all bound to and the only way to change it is top-down? Or is it the constructive result of the surplus that everyone is willing to bring to the table, implying that an individual should have the option to quit the game and take their ball - even if that individual then watches from the sideline or even returns to play but without their ball?
Both perspectives are needed, but every society is predisposed towards over-centralization - most people have a very hard time seeing anything besides their own perspective, so they falsely think their desires apply to everyone. Yet as demonstrated by the success of free markets, only decentralization can satisfy and incorporate minority viewpoints. When creative destruction is prevented from applying to structures within the society, then it will inevitably occur to the society as a whole.