Getting herd immunity may not work.

It may just make the virus endemic.

And if you make the virus endemic you won't be able to "protect seniors" or any other vulnerable group.

That may be how things land up, but let's not kid ourselves about what that outcome means. https://twitter.com/balajis/status/1260626617887453184

Put another way: any organization capable of erecting a semi-permeable membrane between millions of seniors and others such that they could live normal-ish lives without getting the virus would be able to do the same thing for the rest of society.

And we can't do that.

Let's also be clear that any country capable of eradicating the virus wouldn't set "herd immunity" as a goal.

It may work, it may not. It's a roll of the dice you wouldn't take if you had the state capacity of South Korea.

Some of the uncertainties here:
https://www.discovermagazine.com/health/could-we-be-living-with-covid-19-forever

The US may well have to make hard choices due to its lack of state capacity to control COVID-19.

But there's a chance this really tears the social fabric.

If group A of citizens is writing off group B, due to being in a zero sum game, then group C may write off group A later...