Current Events > The R0 value in vaccine induced herd immunity makes no sense.

(+) Yeah! (+)

So I wanted to use my math skills to understand how herd immunity supposedly works. The value of R0 is used to calculate the threshold percentage a population needs to prevent an outbreak. In the case of measles, R0 is about 15, which means a person with measles will infect 15 others. But it doesn't take into consideration how many interactions that person has. Whether it's 0, 100, or 10,000 that person would supposedly infect 15. So Roast, explain that!
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FLOUR posted...

So I wanted to use my math skills to understand how herd immunity supposedly works. The value of R0 is used to calculate the threshold percentage a population needs to prevent an outbreak. In the case of measles, R0 is about 15, which means a person with measles will infect 15 others. But it doesn't take into consideration how many interactions that person has. Whether it's 0, 100, or 10,000 that person would supposedly infect 15. So Roast, explain that!

The basic reproduction number, R0, is defined as the expected number of secondary cases produced by a single (typical) infection in a completely susceptible population. It is important to note that R0 is a dimensionless number and not a rate

For someone who does a "lot of research online" you sure don't know how to Google
It's part of a larger set of equations including infection rate, transmissibility, resistance, prevalence, etc.

By itself it's essentially meaningless. It's like making a broad statement about something knowing only one of several variables.
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Roast just explained it without being tagged

Antivaxxers be like

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Let's not pretend this topic was made in good faith.

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This was the article I read last night. The author uses R0/10 as a rate in his explanation for 10 people. But then uses R0/N as the rate later on. Why the hell would the rate change?

https://www.quantamagazine.org/flu-vaccines-and-the-math-of-herd-immunity-20180205/
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Did you not just read what I posted?

R0 by itself is meaningless. It needs to be adjusted based on population dynamics.

Look man, I get it, funny memes on Facebook and blogs have you convinced that big pHARMa is coming to get you with their vaccine industry that makes almost as much profit as the highly lucrative toothpaste industry.
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is this some anti vaxx bullshit?

herd immunity is real

deal with it

if you dont get your vaxx you are a biological terrorist

stfu and get shots
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Questioning stuff like herd immunity is a sure-fire sign you're dealing with someone who is in deep with the anti-vaxx propaganda. It's an astoundingly stupid ignorance-fueled rabbit hole. If there's one thing I've learned dealing with them, it's that the more you actually explain things, the firmer they become in their beliefs despite being faced with incontrovertible facts.

They actually have Facebook groups where they actively advise against taking statistics courses because they have "brainwashed" former anti-vaxxers into questioning their beliefs.
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All I did was read the article I linked. In these examples, the guy is claiming an infected person that interacts with 10 unvaccinated people will infect 2 of them on average. He then uses some weird logic that if he instead interacted with 1,000 unvaccinated people the answer will remain 2 on average. Why not 200? None of this makes sense without explaining how R0 is calculated which is what the guy failed to do.
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I don't get what this topic was arguing?

That antivaxxing is ok since, when we misinterpret statistics, only a few people will get measles from a carrier?
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Pretending to be this stupid to troll over "being an anti vaxxer" seems a pretty boring way to spend ones time.
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FLOUR posted...

All I did was read the article I linked. In these examples, the guy is claiming an infected person that interacts with 10 unvaccinated people will infect 2 of them on average. He then uses some weird logic that if he instead interacted with 1,000 unvaccinated people the answer will remain 2 on average. Why not 200? None of this makes sense without explaining how R0 is calculated which is what the guy failed to do.

From your article:

Like all elementary models, it ignores or simplifies many complicating factors

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FLOUR posted...

All I did was read the article I linked. In these examples, the guy is claiming an infected person that interacts with 10 unvaccinated people will infect 2 of them on average. He then uses some weird logic that if he instead interacted with 1,000 unvaccinated people the answer will remain 2 on average. Why not 200? None of this makes sense without explaining how R0 is calculated which is what the guy failed to do.

The rate at which a disease spreads through unvaccinated hosts is contingent on the disease and not the person.

If I put bacteria into a culture dish it will grow at a certain rate until the whole dish is overrun with bacteria. If I put it into the same dish but half the dish is raw bacteria-killing salt, the bacteria still multiplies at the same rate it just dies when it touches the salt. If there's some not salt at the far end, that place remains out of reach of the bacteria.

That's the closest example I can come up with that is analogous to your vague hypothetical problem.

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