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> It really only takes about 100M vaccines to hit herd immunity. Citation please? Dr. Fauchi says we need 70% innoculations to achieve herd immunity. https://n

> It really only takes about 100M vaccines to hit herd immunity. Citation please? Dr. Fauchi says we need 70% innoculations to achieve herd immunity. https://news.yahoo.com/fauci-america-reach-herd-immunity-004356332.html https://news.yahoo.com/fauci-america-reach-herd-immunity-004... From the numbers I've been able to gather, you need 200M vaccinated people to achieve herd immunity, which is 400M doses. Sources: Wikipedia gives the US population as 308,401,808. Seventy percent of that is 215,881,266. Latest COVID-19 infection totals come to about 16 million. https://www.nytimes.com/interactive/2020/us/coronavirus-us-cases.html https://www.nytimes.com/interactive/2020/us/coronavirus-us-c... Unclear why I'm being downvoted.

aqme28 6y ago
He's saying that if 100M already have natural immunity, then 100M with a vaccine brings us closet to that 70%.
- FlyMoreRockets 6y ago
  100M doses brings us closer to 17%. We need 400M doses to innoculate 200M people, which is what we need to achieve 70%, counting the 16M people that have been diagnosed with the disease.
- ineedasername 6y ago
  Except we don't know who those 100M people are so we can't exclude them from the vaccination pool.
tppiotrowski 6y ago
I believe the author meant 100M infected by February (and assumed immune) + 100M more vaccinated is about 66% of the current US population of 328M.
- ummonk 6y ago
  They can't be added up like that though, since some of the previously infected will still be vaccinated. So it'll be more like 170 million total with 100 million vaccinated.
mlyle 6y ago
70% is the kind of "default" number. It's based on 1-1/R0. If R0 is 3, then you need 66.7% to no longer be susceptible before cases start to decay. If the vaccine is 95% effective, then you need about 70% vaccinated to get 66.7% no longer susceptible. But: 1-1/R0 assumes universal, uniform susceptibility and uniform contact graph, which aren't true-- so it's pessimistic. And some people have caught the virus already and are no longer susceptible through that means. Many computational models put it at about `25% of people infected will result in herd immunity with normal behavior, and the US is presently at about 16%. Unfortunately, getting the "right" additional 9% of people will require vaccinating much more than 9% of the population (we're not as good at selecting the most susceptible and most involved in spreading as the virus itself), but substantially less than 70%. Further, R0 is based on baseline behavior. I suspect a decent chunk of us will be much more careful for some time, which effectively changes the required decrease in susceptibility to cause a case count decay. > Latest COVID-19 infection totals come to about 16 million. https://www.nytimes.com/interactive/2020/us/coronavirus-us-c https://www.nytimes.com/interactive/2020/us/coronavirus-us-c... Current COVID-19 infection total estimate per CDC is about 53 million infections so far. https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/burd https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/burd...
- FlyMoreRockets 6y ago
  Sure, there may be 53M infections, but how many of those untested positives will go on to get a vaccine? This will actually hinder herd immunity, wasting limited vaccines.
  - mlyle 6y ago
    > Sure, there may be 53M infections, but how many of those untested positives will go on to get a vaccine? This will actually hinder herd immunity, wasting limited vaccines. Oh, ideally you wouldn't vaccinate people who are already immune, but saying it hinders herd immunity is a bit silly. I find it's always helpful to do thought experiments at the limit. Do you think reaching herd immunity requires more doses A) in a population that is 99% of the way to herd immunity, but that 25% of doses will be wasted because they'll be given to people who are already immune, or B) in a population that is 1% of the way to herd immunity, but only 4% of doses will be wasted in this way?
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aqme28 6y ago

He's saying that if 100M already have natural immunity, then 100M with a vaccine brings us closet to that 70%.

FlyMoreRockets 6y ago
100M doses brings us closer to 17%. We need 400M doses to innoculate 200M people, which is what we need to achieve 70%, counting the 16M people that have been diagnosed with the disease.
ineedasername 6y ago
Except we don't know who those 100M people are so we can't exclude them from the vaccination pool.

tppiotrowski 6y ago

I believe the author meant 100M infected by February (and assumed immune) + 100M more vaccinated is about 66% of the current US population of 328M.

ummonk 6y ago
They can't be added up like that though, since some of the previously infected will still be vaccinated. So it'll be more like 170 million total with 100 million vaccinated.

mlyle 6y ago

70% is the kind of "default" number. It's based on 1-1/R0. If R0 is 3, then you need 66.7% to no longer be susceptible before cases start to decay. If the vaccine is 95% effective, then you need about 70% vaccinated to get 66.7% no longer susceptible. But: 1-1/R0 assumes universal, uniform susceptibility and uniform contact graph, which aren't true-- so it's pessimistic. And some people have caught the virus already and are no longer susceptible through that means. Many computational models put it at about `25% of people infected will result in herd immunity with normal behavior, and the US is presently at about 16%. Unfortunately, getting the "right" additional 9% of people will require vaccinating much more than 9% of the population (we're not as good at selecting the most susceptible and most involved in spreading as the virus itself), but substantially less than 70%. Further, R0 is based on baseline behavior. I suspect a decent chunk of us will be much more careful for some time, which effectively changes the required decrease in susceptibility to cause a case count decay. > Latest COVID-19 infection totals come to about 16 million. https://www.nytimes.com/interactive/2020/us/coronavirus-us-c https://www.nytimes.com/interactive/2020/us/coronavirus-us-c... Current COVID-19 infection total estimate per CDC is about 53 million infections so far. https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/burd https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/burd...

FlyMoreRockets 6y ago
Sure, there may be 53M infections, but how many of those untested positives will go on to get a vaccine? This will actually hinder herd immunity, wasting limited vaccines.
- mlyle 6y ago
  > Sure, there may be 53M infections, but how many of those untested positives will go on to get a vaccine? This will actually hinder herd immunity, wasting limited vaccines. Oh, ideally you wouldn't vaccinate people who are already immune, but saying it hinders herd immunity is a bit silly. I find it's always helpful to do thought experiments at the limit. Do you think reaching herd immunity requires more doses A) in a population that is 99% of the way to herd immunity, but that 25% of doses will be wasted because they'll be given to people who are already immune, or B) in a population that is 1% of the way to herd immunity, but only 4% of doses will be wasted in this way?

deleted 6y ago

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