Waves in time, but not in space – An analysis of pandemic severity of COVID-19 in Germany based on spatio-temporal clustering

While pandemic waves are often studied on the national scale, they typically are not distributed evenly within countries. This paper employs a novel approach to analyze the tempo-spatial dynamics of the COVID-19 pandemic in Germany. First, we base the analysis on a composite indicator of pandemic severity to gain a more robust understanding of the temporal dynamics of the pandemic. Second, we subdivide the pandemic during the years 2020 and 2021 into fifteen phases, each with a coherent trend of pandemic severity. Third, we analyze the patterns of spatial association during each phase. Fourth, similar types of trajectories of pandemic severity among all German counties were identified through hierarchical clustering. The results imply that the hotspots and cold spots of the first four waves of the pandemic were relatively stationary in space so that the pandemic moved in time but less in space.