Lancaster Area Growth Rate in Confirmed Cases by Case Count per 1,000 Population

What Does This Graph Show?

This graph is one of the most useful for interpreting the direction the epidemic is taking. On the horizontal axis is the number of cases per 1,000 population. On the vertical axis is the change in the growth rate of cases. The key concept here is that if the number of cases is growing quickly, but there are few people in the population with infections (the lower left quadrant of the graph) that is much less concerning than if the number of cases is growing rapidly and there are many people in the population infected. Typically in epidemics there is a rapid growth of cases early. As these cases are detected, interventions, like social distancing, are put in place and the growth rate slows. If over time the growth rate continues to be high and the proportion of the population infected grows large — that will lead to a rapid and large epidemic. In other words, high growth rates combined with a large number of confirmed cases is a dangerous combination.