Blog article: Disease Outbreak Concerns in Toronto’s Long-Term Care Homes

Disease Outbreak Concerns in Toronto’s Long-Term Care Homes

Article text

Our first student guest blog was written by Benny Rochwerg, a fourth-year undergraduate student at the University of Toronto, St. George Campus in the Chemical Physics Specialist, Statistics Minor, and Mathematics Minor programs. He has several years of professional and volunteer tutoring experience in mathematics, physics, and chemistry. This paper was written for STA302H1 (Methods of Data Analysis) at the University of Toronto with Professor Rohan Alexander.


Following the World Health Organization’s COVID-19 pandemic proclamation in 2020, 81% of deaths from COVID-19 in Canada occurred among long-term care residents. Since Toronto recently experienced high influenza and COVID-19 activity, it is critical to evaluate disease outbreaks in Toronto healthcare facilities.

Toronto Public Health defines an outbreak as “a localized increase (e.g. in an institution, or a specific ward or floor within an institution) in the rate of infection or illness, above that which is expected.” To gain insight into this issue, the R programming language and several R packages were used to examine Toronto Public Health “Outbreaks in Toronto Healthcare Institutions” open data from 2023.


Figure 1. Number of outbreaks at each Toronto healthcare location type in 2023

As demonstrated in Figure 1, the majority of Toronto healthcare outbreaks in 2023 occurred in long-term care homes, followed by retirement homes, chronic care hospital settings, acute care hospital settings, psychiatric hospital settings, and transitional care facilities.

Figure 2. Number of outbreaks of each type in Toronto healthcare facilities in 2023

Also, Figure 2 highlights that approximately 95% of Toronto healthcare outbreaks in 2023 were respiratory with relatively few enteric outbreaks or other outbreak types.

Figure 3. Number of outbreaks for each first known cause in Toronto healthcare facilities in 2023.

Moreover, Figure 3 shows that COVID-19 was the first known cause of approximately two-thirds of Toronto healthcare outbreaks in 2023. In contrast, other agents were represented to a much lesser extent.


As illustrated in the Results section, most of the Toronto healthcare facility outbreaks occurred in long-term care homes, were respiratory, and had COVID-19 as their first known cause. These outcomes may have been exacerbated by the Government of Ontario’s 2022 decision to eliminate mandatory masking in long-term care homes for visitors and caregivers. This is despite the fact that long-term care residents tend to be at least 65 years old as of 2018, an age group that is more susceptible to worse health impacts from COVID-19.

The outbreak data examined here was likely an underestimate of the true total given that asymptomatic disease may not have been detected and recorded and that secondary drivers of each outbreak were not assessed. Consequently, long-term care home disease outbreaks in Toronto and in Canada overall should be investigated to gain a better understanding of this significant issue.

Attribution Statement

“Contains information licensed under the Open Government Licence – Toronto.”

Original Paper

This blog post is a summary of my 2024 paper titled “Long-term care homes were hit hardest by 2023 disease outbreaks in Toronto healthcare facilities” (available here). The GitHub Repository associated with this paper is available here.