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> Obviously a lockdown can cause the number of cases to go down. Maybe I'm just ignorant, but could you explain how a lockdown is supposed to decrease the tota

> Obviously a lockdown can cause the number of cases to go down. Maybe I'm just ignorant, but could you explain how a lockdown is supposed to decrease the total number of cases rather than just prolong it? A lockdown does not make a population more resilient to a virus. It just reduces contagion vectors so it spreads more slowly. The virus still spreads, though. Eventually, enough of the population will catch the virus and build up a resistance to it so that herd immunity kicks in. At that point, enough people will have been exposed to the virus that it does not have enough people to spread to and simply dies out. I suppose the threshold for herd immunity is lower in a lockdown situation, but I am skeptical about it working to that extent. If my skepticism is misplaced and the lockdown really is that effective, then that also means India will have to stay on lockdown for a very long time to keep that herd immunity threshold low and completely starve the virus out.

pjc50 7y ago
Once you get "R" below 1, the number of cases goes down. Once the number of cases is small enough, you can identify and quarantine all of them. With a good enough testing infrastructure this gets easier. You can then have a "selective" lockdown only around actual cases.
- jfoster 7y ago
  Yes. A bunch of countries have entered (or are about to enter) this phase: New Zealand, Australia, South Korea, Taiwan
- CivBase 7y ago
  > Once the number of cases is small enough, you can identify and quarantine all of them. A nation is not a closed system so I don't see that ever working out.
  - fulafel 7y ago
    What about the eventual vaccine?
twomoretime 7y ago
>Maybe I'm just ignorant, but could you explain how a lockdown is supposed to decrease the total number of cases rather than just prolong it It's not so black and white. We're talking about the area under the curve. The area under the curve varies nonlinearly with R0. But yes, because of the nature of the logistic function, a flatter curve will lead to fewer cases overall, once you factor in time and the assumption that eventually for whatever reason it will go away.

pjc50 7y ago

Once you get "R" below 1, the number of cases goes down. Once the number of cases is small enough, you can identify and quarantine all of them. With a good enough testing infrastructure this gets easier. You can then have a "selective" lockdown only around actual cases.

jfoster 7y ago
Yes. A bunch of countries have entered (or are about to enter) this phase: New Zealand, Australia, South Korea, Taiwan
CivBase 7y ago
> Once the number of cases is small enough, you can identify and quarantine all of them. A nation is not a closed system so I don't see that ever working out.
- fulafel 7y ago
  What about the eventual vaccine?

twomoretime 7y ago

>Maybe I'm just ignorant, but could you explain how a lockdown is supposed to decrease the total number of cases rather than just prolong it It's not so black and white. We're talking about the area under the curve. The area under the curve varies nonlinearly with R0. But yes, because of the nature of the logistic function, a flatter curve will lead to fewer cases overall, once you factor in time and the assumption that eventually for whatever reason it will go away.