Calculate the herd immunity threshold — the proportion of a population that must be immune to stop disease transmission — from the basic reproduction number (R₀) of an infectious disease. Use this tool in epidemiology teaching or when evaluating vaccination campaign targets: the formula 1 − 1/R₀ shows that diseases with higher R₀ (such as measles at 12–18) require 92–95% coverage to interrupt transmission. The result directly informs public health decisions about vaccine coverage goals and outbreak response planning.

About Herd Immunity

Herd immunity occurs when a sufficient proportion of a population is immune to an infectious disease, interrupting transmission and protecting vulnerable individuals. The threshold is calculated as 1 − 1/R₀, where R₀ is the basic reproduction number of the pathogen. For measles (R₀ = 12–18), this means 92–95% vaccination coverage is required.