Abstract
Objectives: To analyse nosocomial transmission in the early stages of the coronavirus 2019 (COVID-19) pandemic at a large multisite healthcare institution. Nosocomial incidence is linked with infection control interventions.
Methods: Viral genome sequence and epidemiological data were analysed for 574 consecutive patients, including 86 nosocomial cases, with a positive PCR test for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during the first 19 days of the pandemic.
Results: Forty-four putative transmission clusters were found through epidemiological analysis; these included 234 cases and all 86 nosocomial cases. SARS-CoV-2 genome sequences were obtained from 168/234 (72%) of these cases in epidemiological clusters, including 77/86 nosocomial cases (90%). Only 75/168 (45%) of epidemiologically linked, sequenced cases were not refuted by applying genomic data, creating 14 final clusters accounting for 59/77 sequenced nosocomial cases (77%). Viral haplotypes from these clusters were enriched 1-14x (median 4x) compared to the community. Three factors implicated unidentified cases in transmission: (a) community-onset or indeterminate cases were absent in 7/14 clusters (50%), (b) four clusters (29%) had additional evidence of cryptic transmission, and (c) in three clusters (21%) diagnosis of the earliest case was delayed, which may have facilitated transmission. Nosocomial cases decreased to low levels (0-2 per day) despite continuing high numbers of admissions of community-onset SARS-CoV-2 cases (40-50 per day) and before the impact of introducing universal face masks and banning hospital visitors.
Conclusion: Genomics was necessary to accurately resolve transmission clusters. Our data support unidentified cases-such as healthcare workers or asymptomatic patients-as important vectors of transmission. Evidence is needed to ascertain whether routine screening increases case ascertainment and limits nosocomial transmission.
Original language | English |
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Pages (from-to) | 93-100 |
Number of pages | 8 |
Journal | Clinical Microbiology and Infection |
Volume | 28 |
Issue number | 1 |
Early online date | 20 Dec 2021 |
DOIs | |
Publication status | Published - 1 Jan 2022 |
Keywords
- COVID-19/epidemiology
- cross infection/epidemiology
- disease outbreaks
- genome, viral
- genomics
- hospitals
- humans
- pandemics
- SARS-CoV-2/genetics
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Dataset: GISAID EpiCov SARS-CoV-2 Whole Genome Sequencing Database
Robson, S. (Creator), GISAID, 18 Nov 2020
https://www.epicov.org/epi3/frontend#3bd481
Dataset
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COVID-19 Genomics UK (COG-UK) consortium
Robson, S. (Creator), NCBI, 29 Apr 2020
https://www.ncbi.nlm.nih.gov/bioproject/?term=PRJEB37886
Dataset