My only issue is that vaccines for contagious diseases are not necessarily a personal or private matter.

What if a new strain of covid made your penis fall off with 20% likelihood. And the chances of spreading it were reduced to 0 if vaccinated. Would you be invested in your neighbors getting the vaccine?

I think there'd be broad political support for everybody getting the vaccine so that we could preserve everyone's penises. Even if mandates be required for the crazy, malicious and/or stupid.

Same idea but with the variables slightly tweaked.