Thread by @kylamb8, Herd Immunity. I'm devoting this thread to it because it's a possible [...]

Herd Immunity. I& #39;m devoting this thread to it because it& #39;s a possible way out. There are a lot of Herd Immunity Threshold (HIT) deniers out there over theories that the virus is burning out at 15-20%. I& #39;m about to throw some cold water in the faces of the deniers.

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I can& #39;t prove, and won& #39;t attempt to suggest I can, that we are reaching herd immunity in the U.S. However, after seeing the data I have to offer, anyone would be cray to dismiss the possibility out of hand. First, let& #39;s discuss what herd immunity actually is.

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Let& #39;s explain herd immunity from an excerpt found on the Mayo Clinic website:

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https://www.mayoclinic.org/diseases-conditions/coronavirus/in-depth/herd-immunity-and-coronavirus/art-20486808">https://www.mayoclinic.org/diseases-...

Generally speaking, herd immunity is reached when anywhere from 40 to 80 percent of a population has been infected. As mentioned by Mayo, measles needs 94% threshold before achieving immunity.

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In the early days, when U.S. deaths projections were 2, 3 or 4 million people, it& #39;s because herd immunity was not considered reasonable to achieve without great loss of life. See this excerpt from MIT Technology Review on March 17.

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https://www.technologyreview.com/2020/03/17/905244/what-is-herd-immunity-and-can-it-stop-the-coronavirus/">https://www.technologyreview.com/2020/03/1...

We have learned and are still learning a lot about this virus. It turns out, we might not need to get to 60 or 80% to achieve immunity. One possible explanation is T cell resistance.

See this July 28 entry on the NIH director& #39;s blog

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https://directorsblog.nih.gov/2020/07/28/immune-t-cells-may-offer-lasting-protection-against-covid-19/">https://directorsblog.nih.gov/2020/07/2...

There is still a lot of pushback against T cell immunity, or at least whether it& #39;s possible it& #39;s providing a possible 15 to 20 percent immunity threshold.

Many people have now theorized the 15-20% burnout on observation and it was first popularized by @MLevitt_NP2013

7/8

I& #39;m here to tell you, there is evidence for it. Getting data from http://covid19-projections.com"> http://covid19-projections.com which estimates the number of true infections (actual number with the virus rather than just confirmed cases), I found 15 states have reached at least 10% infected 45 days ago or more

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First, let& #39;s look at 13 of those 15 states and see what 7 day case averages look like when done on a per 1 million basis (MS had unreliable case data and NY began so early in testing so both of these states were excluded); 21 days prior to reaching 10% threshold...

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The previous chart shows a very similar upward trajectory in every state except for Louisiana, which was a clear outlier. Rhode Island was also a bit of an outlier, but most states continued to increase.

Now watch what happens when they hit 10 percent.

10/11

Although not every state was the exact same (Louisiana was an outlier again skyrocketing then sharply falling after 40+ days), states all level off and start falling within 1-3 weeks of hitting 10 percent. This fits the 15-20% threshold.

See the before & after.

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Again, this is not proof of herd immunity threshold being 15-20% for Covid-19, but it& #39;s difficult to argue other causes. Mask mandates, lockdowns, etc. simply were not uniform. I have been on the fence on H.I.T., but this, for me, is strong evidence for it.

/End

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