A systematic outbreak investigation of SARS-CoV-2 transmission clusters in a tertiary academic care center

von Rotz, M. and Kuehl, R. and Durovic, A. and Zingg, S. and Apitz, A. and Wegner, F. and Seth-Smith, H. M. B. and Roloff, T. and Leuzinger, K. and Hirsch, H. H. and Kuster, S. and Battegay, M. and Mariani, L. and Schaeren, S. and Bassetti, S. and Banderet-Uglioni, F. and Egli, A. and Tschudin-Sutter, S.. (2023) A systematic outbreak investigation of SARS-CoV-2 transmission clusters in a tertiary academic care center. Antimicrob Resist Infect Control, 12. p. 38.

[img] PDF - Published Version
Available under License CC BY (Attribution).


Official URL: https://edoc.unibas.ch/94581/

Downloads: Statistics Overview


BACKGROUND: We sought to decipher transmission pathways in healthcare-associated infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) within our hospital by epidemiological work-up and complementary whole genome sequencing (WGS). We report the findings of the four largest epidemiologic clusters of SARS-CoV-2 transmission occurring during the second wave of the pandemic from 11/2020 to 12/2020. METHODS: At the University Hospital Basel, Switzerland, systematic outbreak investigation is initiated at detection of any nosocomial case of SARS-CoV-2 infection, as confirmed by polymerase chain reaction, occurring more than five days after admission. Clusters of nosocomial infections, defined as the detection of at least two positive patients and/or healthcare workers (HCWs) within one week with an epidemiological link, were further investigated by WGS on respective strains. RESULTS: The four epidemiologic clusters included 40 patients and 60 HCWs. Sequencing data was available for 70% of all involved cases (28 patients and 42 HCWs), confirmed epidemiologically suspected in house transmission in 33 cases (47.1% of sequenced cases) and excluded transmission in the remaining 37 cases (52.9%). Among cases with identical strains, epidemiologic work-up suggested transmission mainly through a ward-based exposure (24/33, 72.7%), more commonly affecting HCWs (16/24, 66.7%) than patients (8/24, 33.3%), followed by transmission between patients (6/33, 18.2%), and among HCWs and patients (3/33, 9.1%, respectively two HCWs and one patient). CONCLUSIONS: Phylogenetic analyses revealed important insights into transmission pathways supporting less than 50% of epidemiologically suspected SARS-CoV-2 transmissions. The remainder of cases most likely reflect community-acquired infection randomly detected by outbreak investigation. Notably, most transmissions occurred between HCWs, possibly indicating lower perception of the risk of infection during contacts among HCWs.
Faculties and Departments:09 Associated Institutions > Swiss Tropical and Public Health Institute (Swiss TPH)
09 Associated Institutions > Swiss Tropical and Public Health Institute (Swiss TPH) > Department of Directorate (DIR) > Medical Services (K├╝nzli/Neumayr)
UniBasel Contributors:Durovic, Ana
Item Type:Article, refereed
Article Subtype:Research Article
ISSN:2047-2994 (Electronic)2047-2994 (Linking)
Note:Publication type according to Uni Basel Research Database: Journal article
Related URLs:
Identification Number:
edoc DOI:
Last Modified:09 May 2023 07:39
Deposited On:09 May 2023 07:39

Repository Staff Only: item control page