Mason  🏃‍♂️ ✂️

If we're to trust the Wuhan data, it took 2 weeks for daily new cases to begin dropping. The good news is that once that begin, the decline was ~as steep as the growth. The bad news is that cumulative active cases continued to rise for some time.https://twitter.com/NateSilver538/status/1240689047418236932 …

Isn't that problematic? Unless lockdown becomes permanent, don't we want a continued slow growth of cases to create herd immunity? We're still a year from having a vaccine, so our only option at the moment is controlled infection.

"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