Figure 3: Critical community size of CV-A16.
From: Hand, Foot, and Mouth Disease in China: Critical Community Size and Spatial Vaccination Strategies

Population per county as a function of the proportion of zeros in weekly incidence for observed and predicted time series. The intersection the fitted function with the y-axis indicated the estimate of the critical community size for CV-A16. N is the number of counties with at least one epidemic fadeout.