Figure 3.

Distribution of SARS-CoV-2 cases according to time, their cluster, and epidemiological or genomic basis for inclusion in a cluster, Düsseldorf, Germany, 01 July–31 July 2021 (n = 850 cases)

IP: infected return traveller, which is considered as the index case; SARS-CoV-2: severe acute respiratory coronavirus syndrome coronavirus 2.

The figure shows daily new registered SARS-CoV-2 cases in Düsseldorf in July 2021, and how many of these were associated with Cluster 1 or Cluster 2. For Cluster 1, ‘directly linked to index case’ refers to uninterrupted, contact tracing-supported putative transmission chains between the linked cases and IP; ‘genotype’ refers to respective case samples that were identified as belonging to Cluster 1 in the phylogenetic tree analysis (see text). For Cluster 2, ‘directly linked to travel from Catalonia’ refers to cases who either recently returned from Catalonia and to cases who were directly linked to Catalonia returnees in a manner supported by contact tracing; ‘genotype’ refers to respective case samples that were identified as belonging to Cluster 2 in the phylogenetic tree analysis (see text).