Fig. 3
From: A novel method to detect the early warning signal of COVID-19 transmission
The early warning signals of COVID-19 in Germany. a Construct the country network by German geographical location. b The early warning signal of the outbreak of COVID-19 in Germany between June 28, 2021 and September 29, 2021. The red line depicts the ARNN-LNE index calculated by the algorithm in Sect. 2.2, whereas the blue line represents the daily news case of COVID-19, which was derived from raw data after smoothing filtering processing. The ARNN-LNE index can be considered an early warning signal if it exceeds this green line which stands for the threshold. The yellow circle with a red star is the formal signal, while the purple diamond denotes the peak of new daily cases. c The detailed information about the nodes in this network