Medical bioethics is treacherous territory. At the extreme, it involves a person deciding who should live and who should die. Simply engaging in this calculus is morally damaging, and so, when presented with tough choices, we are better served by simple, maybe even arbitrary, rules rather than complex calculations.

Accordingly, our coronavirus vaccine distribution plan should be as simple as possible. We’ve decided that doctors and nurses, particularly those most likely to treat COVID patients, ought to go first. That makes enough sense. But after that, things get grayer, and the calculations that go into making a nuanced, multi-layered priority last become dicey.