Here are some observations from reading various news and medical websites.

1. Herd immunity is calculated as (R0-1)/R0. So if R0 is 3 we need 2/3 of the population to be immune to achieve herd immunity.
2. R0 for Covid 19 is generally given as between 2 and 3. That would mean that we need something like 50-66%. Yikes, that's a lot of people!
3. If we get a vaccine, we win because the percentage of immune jumps by a lot. But a vaccine is, at best, a year away. We can't keep our economy in an induced coma for that long.
4. R0 for this disease is not a constant. It's some sort of hash of the transmissiblity of the disease and human behavior. If our form of greeting is to wave from far away, R0 goes down. If it's to pick each others noses, R0 goes up.

So...
4. The name of the game is to manage infections but not suppress them completely. We need as many people to become infected (and live) as possible without overwhelming the health care system. Somehow, we have to gradually release the screws and watch the infection rate. Further, we need to skew those infections to those people that are most likely to survive them. The goal is that magic herd immunity even if we go back to pre-pandemic behaviors.

If I'm right in the above points, we have a long way to go. The alternative would be to tamp this thing down and then be super vigilant so that any infection doesn't spread out of control. Then we would sort of live with the virus until there's a vaccine.