Fig. 1

Ward floor plan of Clusters a–d with colored squares representing SARS-CoV-2 positive patients. Numbers represent individual patients, which may have been hospitalized in different rooms within a ward. The virus-strains of patients represented by a blue square are identical, whereas patients with unique virus-strains are indicated by a green square. Patients with no sequencing data available are represented by grey squares. There were two patients in cluster a in adjacent rooms with the same virus-strain, but different to the dominant strain within the cluster (*). The index-patient of cluster b (patient number 4) was hospitalized in both wards. Cluster d occurred on a ward containing a dedicated intermediate care unit (IMC). In this figure includes 39 rather than 40 patients as one patient-contact occurred on another unit