Figure 2.

The inferred onset time of the outbreak: the logistic curves well-fit the cumulative data of ARI incidences across regions with the snippets of the comparison shown for six regions in Period 2. The inferred onset time of the outbreak is the intersection between the fitted curve (orange line) and the actual data (blue dots). The threshold varies among regions depending on the population size–regions with higher population size require more cases to reach the outbreak status.