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Herd Immunity Threshold Calculator

Vaccination coverage needed to halt spread.

Compute the herd immunity threshold p_c = 1 − 1/R₀ — the minimum fraction of the population that must be immune to prevent sustained transmission of an infection with basic reproduction number R₀.

Priya Venkatesan By Priya Venkatesan
Reviewed by Dr. Helena Ortiz
Published Last reviewed 1 min read

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Results

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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

p_c = 1 − 1 / R₀

In depth

Compute the herd immunity threshold p_c = 1 − 1/R₀ — the minimum fraction of the population that must be immune to prevent sustained transmission of an infection with basic reproduction number R₀.