Figure 24.

Simulations of the early epidemic growth phase using the SIR model based on disease generations described by Equations 7 for different values of the basic reproduction number with a power-law scaling parameter α set at 1.0 (i.e., homogenous mixing), $\gamma =\frac{1}{5}$, and a large population size (N=10⁸). The epidemic simulations start with one infectious individual. Because α = 1, the effective reproduction number according to disease generations, R_g, remains invariant during the first few disease generations. As expected, exponential growth during the early growth phase is also evident as a straight line fits well several consecutive disease generations of the epidemic curve.