Transmission of SARS-CoV-2 among healthcare workers and patients in a teaching hospital in the Netherlands confirmed by whole genome sequencing

Paltansing, S.; Sikkema, R.S.; Man, S.J.de; Koopmans, M.P.G.; Munnink, B.B. Oude; Man, P.de

We investigated the sources of infection among healthcare workers (HCWs) and patients in a teaching hospital during the early stages of the COVID-19 pandemic with epidemiological and whole genome sequencing data. This retrospective study is performed in a Dutch teaching hospital with nursing facilities located in Rotterdam and Schiedam with around 45,000 admissions per year. From 3(rd) April to 11(th) May 2020 88 HCWs and 215 patients were diagnosed with SARS-CoV-2 infection. Whole genome sequences were obtained for 30 HCWs and 20 patients. We found 7 sequence types in HCW and 11 in patients. Sequence Cluster A was the most predominant sequence type detected in 23 (77%) HCW, of whom 14 (74%) had direct patient contact and 9 (90%) with indirect patient contact. In addition, seven patients outside of the COVID-19 cohort isolation ward who became positive during their admission were infected with SARS-CoV-2 cluster A. Following universal masking of all HCWs and emphasis on physical distancing during meals and breaks, no further evidence was found for patient to HCW or HCW-to-HCW transmission or vice versa. The identification of genomic cluster A in patients and HCWs infected with SARS-CoV-2 by whole genome sequencing suggests transmission between HCWs, but also from HCWs to patients.