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. 2022 Sep 8;2(1):e151.
doi: 10.1017/ash.2022.288. eCollection 2022.

Factors contributing to a coronavirus disease 2019 (COVID-19) outbreak on a mixed medical-surgical unit in a Canadian acute-care hospital

Megan K McCallum  1 , Glenn Patriquin  2   3   4 , Ian R C Davis  2   3   4 , Tammy MacDonald  1 , Daniel Gaston  2   3 , Jason J LeBlanc  2   3   4 , Yahya Shabi  2   3 , B Lynn Johnston  4
Affiliations

Factors contributing to a coronavirus disease 2019 (COVID-19) outbreak on a mixed medical-surgical unit in a Canadian acute-care hospital

Megan K McCallum et al. Antimicrob Steward Healthc Epidemiol. .

Abstract

Objective: To identify preventable factors that contribute to the cross transmission of severe acute respiratory coronavirus virus 2 (SARS-CoV-2) to patients in healthcare facilities.

Design: A case-control study was conducted among inpatients on a coronavirus disease 2019 (COVID-19) outbreak unit.

Setting: This study was conducted in a medical-surgical unit of a tertiary-care hospital in Nova Scotia in May 2021.

Patients: Patients hospitalized on the unit for at least 12 hours and healthcare workers (HCW) working on the unit within 2 weeks of outbreak declaration were included.

Methods: Risk factors for SARS-CoV-2 infection were analyzed using simple and multiple logistic regression. Whole-genome sequencing (WGS) was performed to identify SARS-CoV-2 strain relatedness. Network analysis was used to describe patient accommodation.

Results: SARS-CoV-2 infections were identified in 21 patients (29.6%) and 11 HCWs (6.6%). WGS data revealed 4 distinct clades of related sequences. Several factors likely contributed to the outbreak, including failure to identify SARS-CoV-2, a largely incomplete or unvaccinated population, and patient wandering behaviors. The most significant risk factor for SARS-CoV-2 infection was room sharing with an infectious patient, which was the only factor that remained statistically significant following multivariate analysis (odds ratio [OR], 9.2l; 95% confidence interval [CI], 2.04-41.67; P = .004).

Conclusions: This outbreak likely resulted from admission of 2 patients with COVID-19, with subsequent transmissions to 17 patients and 11 staff. WGS and bioinformatics analyses were critical to identifying previously unrecognized nosocomial transmissions of SARS-CoV-2. This study supports strategies to reduce nosocomial transmissions of SARS-CoV-2, such as single-patient rooms, promotion of COVID-19 vaccination, and infection prevention and control measures including management of wandering behaviors.

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Figures

Fig. 1.
Fig. 1.
Epidemic curve of COVID-19 infections in patients and staff by day of first positive test in relation to outbreak onset.
Fig. 2.
Fig. 2.
Phylogenetic tree showing genetic distance between all available SARS-CoV-2 specimens collected in Nova Scotia from March 30, 2021, to May 25, 2021.
Fig. 3.
Fig. 3.
Cluster map depicting room sharing relationships among patients on the outbreak unit in the 14 days prior to and 7 days after declaring the outbreak.
See this image and copyright information in PMC

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