It is not just the way it will work, it is on the ONLY way it can work.
We know that herd immunity is a combination of natural immunity and immunity via vaccine. This is not theory, this is established virology science. If someone tells you otherwise, you should question everything they say on the topic.
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www.aamc.org]
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www.verywellhealth.com]
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www.nih.gov]
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www.medpagetoday.com]
We don't know how many people have natural immunity due to being infected because we don't know how many people have actually been infected. We only know how many tests have come back positive. Serologists estimate actual infections at 2-4 times the number of positive tests.
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khn.org]
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www.acsh.org]
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www.npr.org]
So we don't know how many people are immune due to previous infection. And of those people we don't know how many also got vaccinated. As an example, if 100M people have natural immunity and 25M of those got vaccinated, the net number of immunity above the vaccination count is 75M. Thats about 22% of a population of 330M. In this example, if the actual (but currently unknown) percentage of required immunity is 70% and 50% of the total population is vaccinated, then total immunity is 72% and we would be at herd immunity.
But there is no real agreement on the percentage of population required to have immunity to reach herd immunity. Some estimates are as low as 60% and others as high as 90%. Most estimates are in the 70% to 85% range. That is a very large range and not actionable from a policy perspective. Even Fauci refers to percentage required to reach herd immunity as a ‘elusive’.
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www.gavi.org]
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www.marketwatch.com]
Why can't we declare herd immunity when,
and only when, x% of the population gets vaccinated? Why must policy and guidance be based on observed case rates? Ask yourself this question.
Lets say we go with the high end of immunity percentage and if even if we ignore the science of natural immunity. 85% of the population gets vaccinated and we see broad levels of increasing infection rates. Did we reach herd immunity? No, of course not.
Lets say we get to the point of 60% vaccinated and we see infection rates drop to the same levels as every other virus floating around or to zero. Did we reach herd immunity? What will policy and guidance regarding restrictions be then? Do you really think restrictions are not going to be lifted because some bureaucrat got fixated on 70%. Some may believe so, but the real world doesn't work that way - thank goodness.