Figure 1.

Timeline of events during the SARS-CoV-2 nosocomial outbreak. The figure summarizes the main events occurring during the study period, in which day 1 corresponds to the first day of the 15-day period before the large screening. It depicts the day of hospital admission (●), rooms transfer, sample collection for the last negative SARS-CoV-2 test (green), sample collection for the first positive test (pink), transfer to the COVID-19 ward (dark blue) and clinical outcome (death (black), hospital discharge (orange)) for each of the 21 infected patients. The patient numbers are colored according to the phylogenetic reconstruction (as in Figure 2A), where numbers colored in grey indicate samples for which virus genome data could not be obtained. To facilitate the identification of patient-to-patient contact, patient timelines (rows in the figure) are grouped by room (identified by capital letters, see Figure S1). The hospitalization days are highlighted in light blue and the room numbers are indicated on the day a given patient was transferred to that room (the room stay extends until a new transfer appears on the timeline). With the exception of patient 35 (Ward A), all patients and room numbers are relative to Ward B. The presence in other hospital areas is also indicated when relevant (Hemodialysis (Ꚛ), Emergency department (‡)). The date of sample collection for healthcare workers (HCWs) testing positive is also presented at the bottom. The timeline presented starts two weeks before the large test screening and extends until the date of sample collection of the last outbreak-related positive case. Light grey fields (on both sides of the timeline) are included to show events occurring outside the study timeline. (†) List of HCWs with a positive test on large screening: 1,2,4,5,11,13,14,17,18,22,24,27,28,29,31,33 and 40 (no sequencing data). (*), Patient admission before study period; (**), Patient admission and last negative test before the study period.