Approximation of an epidemic curve. The solid line represents the epidemic curve with assumed exponential growth within each reporting interval. The vertical dashed lines separate each reporting interval (week-wise). Growth rate in week k is assumed to be r
k, and the area under the curve of week k (the cumulative incidence in each week) corresponds to the reported weekly incidence C
k. Susceptible individuals in week k, S
k, represent the number of susceptible individuals at the end of week k. The horizontal dotted line indicates the initial value of incidence, i
k and represents the number of new cases at the beginning of week k.