The reason the mandates are so sweeping is because Americans are intensely litigious and making them targeted would potentially run afoul of all sorts of laws like the ADA.
And this problem might be unsolvable - if that's the case then the vaccine mandates (which do lower risk) will probably become as set in stone as MMR shots which, if you went to school in America, you almost certainly got.
2) Sterilizing immunity is a pointless distraction. Seatbelts don't provide 100% protection in a car crash, surgeons washing their hands doesn't prevent 100% of infection, and having smoke alarms and two points of egress in a bedroom will not 100% save your life during a disaster. In fact, I can't even think of a mandated public safety feature that is 100% effective.