Figure 4

Percent increase or decline in the population as a function of the disease’s basic reproductive number (R₀) between the first and second years after the initial infection. The colored lines show four different levels of maximum immunity probability (i.e. P_I of 0.2, 0.4, 0.6, 0.8). The horizontal grey lines show the level at which the population is stationary, and the vertical dashed lines show the mean human R₀.