• Michelle Murti, Monika Goetz, Andrea Saunders, Vidya Sunil, Jennifer L Guthrie, AliReza Eshaghi, Sandra Zittermann, Sarah Teatero, Nahuel Fittipaldi, Heather Rilkoff, Jonathan B Gubbay, Gary Garber, Sandra Callery, Anne Marie Holt, and A Lynn Noseworthy.
• Public Health Ontario (Murti, Saunders, Guthrie, Eshaghi, Zittermann, Teatero, Fittipaldi, Rilkoff, Gubbay, Garber, Callery); University of Toronto (Murti, Fittipaldi, Gubbay, Garber), Toronto, Ont.; Haliburton, Kawartha, Pine Ridge District Health Unit (Goetz, Sunil, Holt, Noseworthy), Port Hope, Ont. Michelle.murti@oahpp.ca.
• CMAJ. 2021 May 10; 193 (19): E681-E688.

BackgroundThe implementation of outbreak management measures has decreased the frequency and severity of SARS-CoV-2 outbreaks in Ontario long-term care homes. We describe the epidemiological and laboratory data from one of the first such outbreaks in Ontario to assess factors associated with its severity, and the impact of progressive interventions for infection control over the course of the outbreak.MethodsWe obtained line list and outbreak data from the public health unit to describe resident and staff cases, severity and distribution of cases over time and within the outbreak facility. Where available, we obtained data on laboratory specimens from the Public Health Ontario Laboratory and performed whole genome sequencing and phylogenetic analysis of viral specimens from the outbreak.ResultsAmong 65 residents of the long-term care home, 61 (94%) contracted SARS-CoV-2, with a case fatality rate of 45% (28/61). Among 67 initial staff, 34 (51%) contracted the virus and none died. When the outbreak was declared, 12 staff, 2 visitors and 9 residents had symptoms. Resident cases were located in 3 of 4 areas of the home. Phylogenetic analysis showed tight clustering of cases, with only 1 additional strain of genetically distinct SARS-CoV-2 identified from a staff case in the third week of the outbreak. No cases were identified among 26 new staff brought into the home after full outbreak measures were implemented.InterpretationRapid and undetected viral spread in a long-term care home led to high rates of infection among residents and staff. Progressive implementation of outbreak measures after the peak of cases prevented subsequent staff cases and are now part of long-term care outbreak policy in Ontario.© 2021 CMA Joule Inc. or its licensors.

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