13 thoughts on “Herd Immunity”

    1. For anyone who has had children in school, as an adult, your immune system is much stronger for the colds and flu you got from your kids.

      The viruses say you’re welcome.

  1. The herd immunity model assumes the population is a uniform herd. The initial outbreak (when its spread looked rapid) hits people who have a large set of daily personal contacts, such as clerks, bartenders, ticket agents, health care workers, police, subway riders, and social butterflies. R0 in these groups is likely to be high. The virus would spread through them pretty rapidly, and from them infect lots of low-contact people who have far fewer daily connections (retirees, linemen, etc), but who often primarily connect into the larger group via these high-contact people. For example, the linemen is likely to talk to the gas station clerk, who talks to everybody. If the gas station clerk is immune, the lineman is much less likely to get infected.

    If the high-contact people develop immunity, they’re no longer passing the infection between the poorly-interconnected low-contact people. This should slow the spread of the virus, and the low-contact people should cause the virus to have a much lower reproduction rate (R0).

    I suspect that’s the kind of thing the British academics were trying to model with their garbage code.

    1. Also high-contact people can get it at about the same time
      and this appear to be air borne, but even mostly about touching your face {wash your hands!!} the high contact mostly infected can all be touching everything in a public space.
      But with airborne it seems you don’t want walk in ward with dozen sick people spreading airborne viruses. And something like a subway is like a ward which constantly moving in and out hundreds of patients per hour. And elevators tiny rooms with dozens of people moving in and out per hour.
      So for pop density areas you have shut down these enclosed spaces in which people are traveling thru. And don’t watch basketball games which has thousands of people crammed to together.

      But anyway lock down period is done, let’s play some baseball.

        1. If soccer has more balls than MLB, does anyone ever want to watch MLB, again?
          “The Bundesliga in Germany is set to become Europe’s first major football league to resume playing during the coronavirus pandemic, with a restart confirmed for this month, it was announced on Wednesday.”

  2. The other key is the right type of testing. Testing for viral presence is, practically speaking, worthless. Since it is only a snapshot, has to be repeated at intervals to be effective and doesn’t indicate as to whether one has HAD the disease or has YET to have it.

    What is needed is serum tests for antibodies. This will tell who has HAD the disease and is likely no longer a spreader. Once the lock down is ended (and it will have to be) we will need to monitor passage of the virus through the population to determine if we have passed over the threshold for herd immunity. Testing will be to monitor the spread of the virus and to some extent limit outbreaks to prevent the healthcare system from being overwhelmed. But not as a means to eliminate the asymptomatic spread of the virus. That is not possible now.

  3. I wonder if Nic Lewis knew at the time of writing of his article what we know today about the Ferguson model? It might not be that hard to be able to out-predict Ferguson20 if you use one that has any form of determinate accuracy. A pretty low bar.

  4. On the Roosevelt and cruise ships, the number of infected topped out at about 20%. Given the circumstances, everyone on board was a high contact person.

    Now the rate in New York is about 20% as well.

    A rate of 20% guarantees that anybody that isn’t living at the bottom of a well has had contact with many infected individuals. If the infection rate was going to be 80%, it should be exploding and isn’t.

    Strangely, there doesn’t seem to be much interest in measuring the rate anywhere else. This is the single number that would give the authorities a half assed idea what reopening would look like. Instead, they average random numbers.

  5. What an absolute pile of BS. No one knows yet who patient zero was, nor can anyone say with any certainty what percentage of covid cases are asymptomatic, or mildly symptomatic. It looks like the modelers of US cases are still going off the first fatality being in Washington state in the last week in February. I heard of one in Santa Clara, CA on February 6. And the results of anti-body tests are all over the map on how many have already had this thing. Herd immunity sounds great, but everyone is still guessing about the where, when, and who brought this to our shores. Reminds me of teenage boys discussing their sexual exploits. Lots of fanfare built on nothing.

    1. Well there was that graduate student who worked at the Wuhan Institute of Virology that disappeared last November from their staff website but that the CCP assures us is fine and well and living somewhere in an undisclosed location…

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