It has been a year and a half.
40 million people in the US have had it.

That means that 280 million haven't.
And we know people catch the corona asymptomatically.

We are looking at immunity for 80 percent of the population before the vaccine.
And the 12 and a half percent that have caught the corona were already sick and being cared for in assisted living facilities.

If you are not understanding this let me simplify.
The shielding approach has already been tried.
It failed.
Isolated elderly and sick in nursing homes WERE being shielded and in that environment they died.

The shielding approach is a plan to kill off the old and sick.