Mason  🏃‍♂️ ✂️

"Herd immunity" is speculative. Immediate reinfection appears very unlikely, but we don't know whether immunity post-infection lasts a few months or a few years.

Herd immunity isn't particularly speculative. If it was, vaccines would be impossible for corona.

The duration of post-infection immunity is speculative. We have annual flu vaccines for a reason, and most communities never build up anything close to herd immunity in any given year. How feasible is it for the novel coronavirus? We just don't know.

Thanks for the clarification and explaining your model.

To check my understanding, an implication you are alluding to is that lockdown cannot end until we have better data (and possibly, not even then, depending on how long immunity lasts), correct?

No, not necessarily. The problem is that there is a ~2-week delay (due to incubation, symptoms slowly arising after) between the actual state of the problem and our knowing about it. Lockdown allows us to see where we stand without making the problem even worse

If after 2 weeks of lockdown the regional medical system is still functional and new cases are beginning to drop at a rate that appears not to overwhelm surge capacity, you can start to relax restrictions and allow *some* new infections

Yes, I believe I understand; however, it seems that you need to go back into a more controlled state shortly after the new infections arise; it's unlikely you can put forward a social policy that people can follow that will allow you to tightly control the infection rate.