Fig. 1
From: A novel method to detect the early warning signal of COVID-19 transmission
Early-Warning. The normal stage, the pre-outbreak stage, and the outbreak stage are the three stages of the COVID-19 dissemination process, according to the DNM theory. The rapidly increasing ARNN-LNE index, shown on the red curve, indicates a transition from the normal stage to the pre-outbreak stage, i.e., the critical point before the upcoming outbreak of COVID-19, as shown by the blue curve