So herd immunity debate continues to rage and occasionally I am asked my opinion. To start out, we can frame the discussion a bit.
1) "herd immunity" from natural SARS-CoV-2 epidemic is certainly not ASSURED. Depends on type and duration of immunity - evolving knowledge.

2) The "magic number" (based on an R0 of 3 or so) is about 70%. If there is a big role for T cell immunity (that is underestimated in population studies) it could be lower. Once you work in the idea that people are in networks/don't mix uniformly - it could be higher or lower.

3) No matter what threshold, an epidemic doesn't STOP when you pass that number - continues til it runs out of fuel (susceptible persons)- so there will be "excess" deaths. The remaining population may have little clusters but shouldn't be subject to large epidemics any more...

...IF (bif IF) natural immunity is long lasting.
At least vaccines can be boosted - and vaccine responses can be better than natural responses.
4) The idea that you can effectively shield the vulnerable and infect the healthy has been proven wrong repeatedly (see- LTC...)

5) Even if you could is the human cost worth it? Isolating the elderly in particular is rather inhumane on a long term basis
6) Let's not forget that young, healthy folk have still gotten critically ill/died, and some survivors can go on to potentially long term health problems.

7) it is not clear that public health interventions are the enemy of the economy: you definitely see economists arguing that the pandemic is itself a factor not shutdowns per se. Uncontrolled epidemics: ill workers, family members, overwhelmed health care for all illnesses...

8) I often see it couched as an either a healthy economy or lockdown, but that's kind of silly: right now most places are trying to balance "opening" society and controlling COVID-19 numbers. Waxing and waning restrictions to reduce illness/death, keep businesses and services...

...open, keep health care functional to serve people with non COVID conditions seems like it should be possible, although it will be challenging, and I'm sure frustrating for the population to walk that line.
9) So
"Let the young get it" seems attractive but is simplistic...

...it neglects their own risks, and it overestimates the ability to shield vulnerable people, and the significant human cost to that. Along with that discussion - "they were going to die anyway"- argh. Devaluing the life of elderly people, is first of all kind of abhorrent....

and actually/actuarially, making it to 80 gives you better odds of making it to 90, so many of these elders had years cut short.
I think we need to ride this out in a controlled way, and our society can't accept those sacrifices.
10) We are learning the parameters of control...

and will get better.
Plan:
Optimize test- trace-isolate.
Better define bubbles, optimal protective measures and "ok" interactions.
Improve COVID-19 treatment and all health care access.

*Learn how our structures failed and when we rebuild them - make them stronger*.
/fin.

I guess shoulda tagged at top but just thought of poking others now
@drdagly @CaulfieldTim @BogochIsaac @GermHunterMD @skepticalIDdoc @zchagla @SharkawyMD @ASPphysician
... thoughts?

(countdown to possible "spirited" debate from Twitter:
3...2...1...)