At some point, SIP will cost more lives than it will save, due to economic and mental effects -.
That's a guess. There have been some economic projections that show the opposite, although I think the inputs and assumpptions to all these models are too speculative to believe.
Flattening the curve doesn't guarantee that the area under it [the number of cases] stays the same. It could be bigger, it could be smaller.
There are other reasons for flattening, besides avoiding overload of the health system. These are largely matters of increased time, including giving more time for researchers to study the disease and its victims, possibly coming up with new or improved treatment modalities that will reduce the risk of death or serious complications; more time to come up with one or more vaccines; more time to graduate or train more health care workers; even more time for mortuaries in NYC to arrange more storage, if you saw the news yesterday. Health care workers not having to work so intensely will probably keep them healthier and less likely to catch the disease themselves.
We don't know how or even if herd immunity will work, because we don't yet have a good understanding of whether a person is immune once recovered or not. We don't know if it depends on how high an antibody level you get, and whether, on a scale of 1-100, you need a 95 or just a 12. We don't know how long any such immunity would last, and whether it depends on the antibody count. We don't know if the virus will mutate, and whether, if it does, any immunity you have will apply to the new version. Extra time will help researchers answer these questions, and consider how to go forward if it turns out badly: that there is little immunity, or it doesn't last long, or the virus mutates into a worse version.
Some old or unhealthy folks will die of other, more ordinary, quicker, gentler, less terrifying problems, many at home with their familes, and not alone in a hospital.
Even if the number of deaths is inevitably the same, there's more time for grandbabies to meet their grandparents; more time to right old wrongs and settle feuds and misunderstanding. I'll bet others are making good use of this extra time.
Herd immunity without a vaccine is not a solution for Covid-19, any more than it is for mumps. There's an explanation
here, but generally the summary is that would still be WAY too many people sick and dead.
I too am anxious to get out and resume having fun. I think those of us who are 70 have at least as much wish not to waste time as those half our age. But just because Solution A is not great, doesn't mean that Solution B has to be better. Solution C, as yet unimagined, might be. Any safe way forward before an effective vaccine involves much more testing, and a contact tracing plan. We all should be asking our leaders why, five months into this, we're not awash in testing materials, kits, and results. And PPE -- where the hell is it?