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O'Grady HM, Harrison R, Snedeker K, Trufen L, Yue P, Ward L, Fifen A, Jamieson P, Weiss A, Coulthard J, Lynch T, Croxen MA, Li V, Pabbaraju K, Wong A, Zhou HY, Dingle TC, Hellmer K, Berenger BM, Fonseca K, Lin YC, Evans D, Conly JM. A two-ward acute care hospital outbreak of SARS-CoV-2 delta variant including a point-source outbreak associated with the use of a mobile vital signs cart and sub-optimal doffing of personal protective equipment. J Hosp Infect 2023; 131:1-11. [PMID: 36195200 PMCID: PMC9527227 DOI: 10.1016/j.jhin.2022.09.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 09/16/2022] [Accepted: 09/27/2022] [Indexed: 01/25/2023]
Abstract
BACKGROUND The arrival of the Delta variant of SARS-CoV-2 was associated with increased transmissibility and illness of greater severity. Reports of nosocomial outbreaks of Delta variant COVID-19 in acute care hospitals have been described but control measures varied widely. AIM Epidemiological investigation of a linked two-ward COVID-19 Delta variant outbreak was conducted to elucidate its source, risk factors, and control measures. METHODS Investigations included epidemiologic analysis, detailed case review serial SARS-CoV-2 reverse transcriptase-polymerase chain reaction (RT-PCR) testing of patients and healthcare workers (HCWs), viral culture, environmental swabbing, HCW-unaware personal protective equipment (PPE) audits, ventilation assessments, and the use of whole genome sequencing (WGS). FINDINGS This linked two-ward outbreak resulted in 17 patient and 12 HCW cases, despite an 83% vaccination rate. In this setting, suboptimal adherence and compliance to PPE protocols, suboptimal hand hygiene, multi-bedded rooms, and a contaminated vital signs cart with potential fomite or spread via the hands of HCWs were identified as significant risk factors for nosocomial COVID-19 infection. Sudden onset of symptoms, within 72 h, was observed in 79% of all Ward 2 patients, and 93% of all cases (patients and HCWs) on Ward 2 occurred within one incubation period, consistent with a point-source outbreak. RT-PCR assays showed low cycle threshold (CT) values, indicating high viral load from environmental swabs including the vital signs cart. WGS results with ≤3 SNP differences between specimens were observed. CONCLUSION Outbreaks on both wards settled rapidly, within 3 weeks, using a `back-to-basics' approach without extraordinary measures or changes to standard PPE requirements. Strict adherence to recommended PPE, hand hygiene, education, co-operation from HCWs, including testing and interviews, and additional measures such as limiting movement of patients and staff temporarily were all deemed to have contributed to prompt resolution of the outbreak.
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Affiliation(s)
- H M O'Grady
- Infection Prevention and Control, Alberta Health Services, Calgary, Alberta, Canada
| | - R Harrison
- Department of Medicine, University of Alberta, Edmonton, Alberta, Canada; Workplace Health and Safety, Alberta Health Services, Edmonton, Alberta, Canada
| | - K Snedeker
- Provincial Population and Public Health, Alberta Health Services, Calgary, Alberta, Canada
| | - L Trufen
- Workplace Health and Safety, Alberta Health Services, Edmonton, Alberta, Canada
| | - P Yue
- Infection Prevention and Control, Alberta Health Services, Calgary, Alberta, Canada
| | - L Ward
- Infection Prevention and Control, Alberta Health Services, Calgary, Alberta, Canada
| | - A Fifen
- Infection Prevention and Control, Alberta Health Services, Calgary, Alberta, Canada
| | - P Jamieson
- Department of Family Medicine, University of Calgary and Alberta Health Services, Calgary, Alberta, Canada; Site Administration, Foothills Medical Centre, Alberta Health Services, Calgary, Alberta, Canada
| | - A Weiss
- Site Administration, Foothills Medical Centre, Alberta Health Services, Calgary, Alberta, Canada
| | - J Coulthard
- Site Administration, Foothills Medical Centre, Alberta Health Services, Calgary, Alberta, Canada
| | - T Lynch
- Department of Pathology & Laboratory Medicine, University of Calgary and Alberta Health Services, Calgary, Alberta, Canada; Genomics and Bioinformatics, Alberta Public Health Laboratory, Alberta Precision Laboratories, Calgary, Alberta, Canada; Alberta Public Health Laboratory, Alberta Precision Laboratories, Calgary, Alberta, Canada
| | - M A Croxen
- Alberta Public Heath Laboratory, Alberta Precision Laboratories, Edmonton, Alberta, Canada; Department of Laboratory Medicine, University of Alberta, Edmonton, Alberta, Canada; Li Ka Shing Institute of Virology, University of Alberta, Edmonton, Alberta, Canada
| | - V Li
- Alberta Public Heath Laboratory, Alberta Precision Laboratories, Edmonton, Alberta, Canada
| | - K Pabbaraju
- Alberta Public Health Laboratory, Alberta Precision Laboratories, Calgary, Alberta, Canada
| | - A Wong
- Alberta Public Health Laboratory, Alberta Precision Laboratories, Calgary, Alberta, Canada
| | - H Y Zhou
- Alberta Public Health Laboratory, Alberta Precision Laboratories, Calgary, Alberta, Canada; Department of Microbiology, Immunology, and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
| | - T C Dingle
- Department of Pathology & Laboratory Medicine, University of Calgary and Alberta Health Services, Calgary, Alberta, Canada; Alberta Public Health Laboratory, Alberta Precision Laboratories, Calgary, Alberta, Canada
| | - K Hellmer
- Site Administration, Foothills Medical Centre, Alberta Health Services, Calgary, Alberta, Canada
| | - B M Berenger
- Department of Pathology & Laboratory Medicine, University of Calgary and Alberta Health Services, Calgary, Alberta, Canada; Alberta Public Health Laboratory, Alberta Precision Laboratories, Calgary, Alberta, Canada
| | - K Fonseca
- Alberta Public Health Laboratory, Alberta Precision Laboratories, Calgary, Alberta, Canada; Department of Microbiology, Immunology, and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
| | - Y-C Lin
- Li Ka Shing Institute of Virology, University of Alberta, Edmonton, Alberta, Canada; Department of Medical Microbiology & Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - D Evans
- Li Ka Shing Institute of Virology, University of Alberta, Edmonton, Alberta, Canada; Department of Medical Microbiology & Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - J M Conly
- Infection Prevention and Control, Alberta Health Services, Calgary, Alberta, Canada; Department of Pathology & Laboratory Medicine, University of Calgary and Alberta Health Services, Calgary, Alberta, Canada; Department of Microbiology, Immunology, and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada; Department of Medicine, University of Calgary and Alberta Health Services, Calgary, Alberta, Canada; W21C Research and Innovation Centre, O'Brien Institute for Public Health, University of Calgary, Calgary, Alberta, Canada; Snyder Institute for Chronic Diseases, University of Calgary and Alberta Health Services, Calgary, Alberta, Canada.
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