What does 'isolate the vulnerable' even mean?

Those arguing for a more rapid lifting of coronavirus restrictions have a refrain that goes something along the lines of: “Isolate the elderly and more vulnerable populations, and let everybody else go on with their lives.”

The argument does not come out of thin air. It is driven by data showing that, overwhelmingly, those who become severely ill and die as a result of the coronavirus tend to be either older or have an underlying health condition. Children, younger adults, and healthier individuals face very little risk from COVID-19, and yet, they are being asked to endure lockdowns, lose work, and see their businesses crumble.