Figure 1. Expected coverage of a vaccination activity based on the values of ψ and ρ.

The left y-axis presents the proportion of the total target population, while the right y-axis shows the proportion vaccinated as a proportion of the accessible population, ρ. A value of ψ = 0 indicates “perfect” vaccine distribution, where every dose of vaccine reaches an individual not yet vaccinated in this activity, ψ = 1 indicates vaccine distribution equivalent to “vaccination at random,” and values of ψ greater than one indicate even worse performance.