I was not talking about herd immunity in the correct sense, but taking into account the measures already in place. The Rt, the effective reproductive correlates to the percentage of immune people. If the R0 is already 1 the Rt would drop to 0.85 if 15 % are immune. The immunity already in place would help a lot in getting to <1. Would quaranteening areas inside a city help in fighting this, and would it even be politically possible?
Have you ever seen the videos of the Chinese police welding people's apartment door shut? We could try that.
I'm not sure about the R numbers. There seems to be different definitions. Quarantining helps. But we've probably gotten near all the help out of it that we are going to. It would get worse quickly if we try and lift I suspect.
We're making progress on therapeutics, but I don't know how large an effect we can have in the short term.
Even if we somehow maintained quarantine (which we won't), I'm afraid we still have a lot of deaths to come because of the number that are already sick and progressing toward an outcome. For the last month I've been watching the US deaths vs Recovered. That ratio has not improved. We have 600k people already sick. If the current ratio holds, you would expect a significant percentage of those 600k finally resolving into the fatality column.
Unless we really pull out a miracle on the treatment side in the next 3-4 weeks. Anything is possible. But they better hurry.
A vaccine of course is probably still a year off from actual deployment.