Impact of Heterogeneity in Susceptibility on the Statistical Power

<div><p>(A) Susceptibility distributions for different levels of heterogeneity, measured by the coefficient of variation, <i>CV,</i> of the susceptibility distribution. The vaccine is assumed to be 80% effective, <i>VE_S =</i> 0.8.</p> <p>(B) The statistical power depends on the coefficient of variation, <i>CV,</i> for the repeated low-dose challenge design (black lines) and the single low-dose challenge design (green lines). For these plots we assumed trials with six and 12 animals per group and vaccine efficacies of <i>VE_S =</i> 0.67 (dotted lines), <i>VE_S =</i> 0.8 (dashed lines), and <i>VE_S =</i> 0.9 (solid lines).</p>