May 20, 2020 – Memo from Dr. Vera Etches, MOH Public Health
See bottom of post to view map of COVID-19 in Ottawa
A report was released by the Institute for Clinical Evaluative Sciences (ICES) on laboratory COVID-19 testing, patterns of testing, and the proportion of tests that come back positive across the province. ICES is a non-profit research institute that uses population-based health information to produce knowledge on a broad range of health care issues. The report is available online – COVID-19 Laboratory Testing in Ontario: Patterns of Testing and Characteristics of Individuals Tested, as of April 30, 2020. Since this report was published, testing has continued to expand across congregate care settings and now accommodates anyone in the population who has COVID-19-like symptoms. ICES also publishes up-to-date COVID-19 testing dashboards to the public. More information is available on their website.
The information reported by ICES is one way that we can look at how we are comparing to similar municipalities in Ontario; however, it does not provide a complete picture of rates of infection in different jurisdictions. Testing was previously limited to priority groups including health care workers and the test results are limited to what is available in the Ontario Laboratories Information System (OLIS) (to which not all laboratories contribute). I have also seen the data be misinterpreted to suggest a causal link between the level of testing and the rates of infection in the community. The rates of infection in a community are determined by many factors, with populations that have more travel and interactions, more people with older ages in congregate care settings, and lower incomes being at greater risk.
Public Health Ontario’s Epidemiologic summary provides a provincial overview of COVID-19 cases. When reviewing this report, we see that areas hardest hit by COVID-19 are cities in large urban centres. When comparing Ottawa Public Health to other public health units, we see that although we have a higher number of total cases, on a per capita basis we are about the middle for infections detected. It is important to note that generally, the work to flatten the curve seems to have been more successful in rural areas given the lower rate of infection compared to urban areas. There is no data to suggest that Ottawa is off-track in comparison to other jurisdictions of similar size and population density.
Below I have provided excerpts from the May 20, 2020 summary.
- Greater Toronto Area public health units account for 63.4% of cases
- The maps do show that Ottawa has a number and per capita rate of laboratory-confirmed infections comparable to other urban public health units (see Figures 5 and 6).
- Appendix A provides the confirmed cases by public health unit. Below is an excerpt of OPH compared to the peer health groups that Ottawa is typically compared to which is Peer Group B as per Statistics Canada-defined peer groupings. These public health units are characterized by being mainly urban centres with moderate population density.
Table 1: Laboratory-confirmed cases (n=23,774) of COVID-19 by public health unit: Ontario, January 15, 2020 to May 19, 2020
|Public Health Unit Name||Laboratory-confirmed cases||Rate of laboratory-confirmed cases per 100,000 population|
|Ottawa Public Health||1,839||174.4|
|OPH Peer Health Groups|
|Durham Region Health Department||1,290||181.1|
|Halton Region Public Health||587||94.8|
|City of Hamilton Public Health Services||591||99.8|
|Middlesex-London Health Unit||484||95.4|
|Region of Waterloo Public Health and Emergency Services||1,009||172.7|
|Windsor-Essex County Health Unit||798||187.8|
|Toronto Public Health||8,192||262.5|
Canada-wide information is available in the Epidemiological summary of COVID-19 cases in Canada. However, this information is reported at the provincial/territorial level and does not compare statistics for regions/municipalities.
Work is underway with public health colleagues to advance a common set of measures that health units are using to monitor the impact of relaxing restrictions. This initiative will likely provide more information to continue to evaluate progress against the virus across the province compared to Ottawa. I will continue to share information with Council as our “dashboards” evolve.
Publication of Ward-Based COVID-19 Data
As of Wednesday, May 20, 2020 and every two weeks hereafter, OPH will be including a “map snapshot” of COVID-19 cases across Ottawa, based on Ward geography.
I wanted to provide you with information on the nature of this information, its limitations, and important takeaways.
Currently COVID-19 is present in every single community within Ottawa. The wards are administrative boundaries and do not reflect the natural ebb and flow of Ottawa residents within the municipality, nor the communities in which they live, work, play and raise their families.
With this in mind, these maps cannot be used to identify “COVID-19 hot spots” in Ottawa. Areas with lower or higher rates are not safer or more at-risk from COVID-19 transmission.
These maps are based on the place of residence of individuals with confirmed COVID-19 and does not reflect where the disease was contracted. Exposure to COVID-19 can occur anywhere people congregate, such as workplaces or essential services open to the public. It is important for everyone to remember that the best way to limit one’s exposure to COVID-19 is to practice physical distancing, limiting your exposure to your immediate family, and washing your hands.
Due to the high proportion of overall cases in long-term care homes (LTCH) and retirement homes (RH) (i.e. cases linked to outbreaks in LTCH & RH) than in the community at large (i.e. sporadic cases), the number of cases by Ward linked to LTCH/RH outbreaks have been parcelled out and presented in a separate map. However, it is important to note that community transmission is ongoing.
These maps are not intended to assist with service delivery planning, recovery efforts or requests for additional services at a neighbourhood level. OPH continues to work with the health care sector and community partners to ensure we work to support the needs of at-risk populations.
There are many variables that may contribute to the observed rates of COVID-19 in Ottawa Wards including:
- Age: In Ottawa, as well as many other communities affected by COVID-19, individuals over the age of 60 years are more likely to develop a serious infection after contracting the virus and are a priority group for testing. Thus, reported rates of confirmed COVID-19 may be higher in communities with a larger percentage of older adults.
- Rurality: To account for differences in the size of urban and rural populations, rates (i.e. the number of COVID-19 cases per 100,000 population) are provided. Rates in rural wards will be more sensitive to changes in the number residents with COVID-19 cases, as they have smaller population sizes. Rural areas tend to have lower population density that facilitates physical distancing.
- Testing: Testing is essential for monitoring COVID-19 in our community. Provincial testing criteria have varied throughout the response and have previously been limited to priority groups when laboratory capacity was more limited. Only a small fraction of all the persons who were infected with the COVID-19 virus were tested and the number of reported confirmed community cases underestimates the actual number of infections. Information on overall infection rates in Canada will not be available until large studies on COVID-19 antibody presence in blood serum are conducted. Based on available information, the actual number of infections may lie from 5 to more than 30 times the reported number of confirmed cases.
- Social determinants of health: The social determinants of health, such as income and ethnicity, can contribute to differences in disease prevalence and health behaviours. The ICES report found that those who tested positive were more likely to live in neighbourhoods with lower-income, or higher concentration of visible minorities and recent immigrants.
Ottawa Public Health is sharing these maps based on the principle of transparency and appreciates your help in disseminating this information in a responsible manner, acknowledging the limitations of the data.
Where is COVID-19 in Ottawa? Dr. Etches says ‘everywhere’