More The EFFECTIVE reproduction rate (R) is calculated based on the R0 Mathematically, it is: R0*y = R Where y is the proportion of the population susceptible to the disease
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Based on the table above, what's the R for measles in a population with 75% vaccination rates?
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Here's a more difficult question - based on the equation for R, what is the formula to work out the % for herd immunity (HI)?
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This is more complex because you have to think about what herd immunity really means Herd immunity means that each person passes on the disease to fewer than 1 person (on average), so the disease eventually peters out
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What this means, in technical terms, is that R<1 I.e. the effective reproduction rate in the population is less than 1
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Mathematically, this gives us the minimum threshold for herd immunity as: R0*(1-HI) = 1 Where R = 1 and R0 is calculated based on the disease Turning this around, we get: HI =1-(1/RO)
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So to work out the threshold for herd immunity, we just have to solve this for each disease! Pretty cool, huh?
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What's the herd immunity threshold for mumps, based on this formula?
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Completing the formula, we get: HI = 1-(1/4) to 1-(1/7) = .75-.86 = 75-86%
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Replying to @GidMK
What's the threshold for vaccinating against keto brain?
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Unfortunately, there is no upper limit
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