| How have changes in testing affected Data Tracker information? |
As of December 31, 2021, eligibility for PCR/molecular testing was limited to individuals at increased risk of severe outcomes and those living and working in high-risk sites such as hospitals, long-term care homes, retirement homes and congregate living settings.
Only cases with positive PCR or rapid molecular test results are counted as COVID-19 cases in the provincial CCM database. Positive results on rapid antigen tests (RATs) in staff, patients and residents of highest-risk settings may be sufficient for declaring outbreaks in these sites. However, individuals with a positive RAT only, and no positive laboratory test, will not be counted as a case in CCM and on the Data Tracker.
Reduced laboratory testing has led to a greater underestimation of the number of confirmed COVID-19 cases. While infectious disease cases are always undercounted because many asymptomatic infections are not detected, the underestimation of COVID-19 cases has increased significantly as of December 31, 2021, and the counts on the Data Tracker do not accurately represent the true number of cases in Durham Region.
Because PCR/molecular testing is limited to high-risk individuals, it is more likely that those tested will be positive, pushing up the percent positivity rates.
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| What is a confirmed case? |
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A confirmed case is a person who has tested positive for COVID-19 infection based on a PCR or rapid molecular laboratory test. For the COVID-19 case definition, see the Ministry of Health website. The Data Tracker reports only confirmed cases who are residents of Durham Region.
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| Are probable cases reported on the Data Tracker? |
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The Health Department does not report probable cases because they represent a small number, may change status to become confirmed cases, and the definition of a probable case has changed greatly over the course of the pandemic. Refer to the Ontario Ministry of Health’s current definition.
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| Why are your numbers sometimes different from what is reported provincially on the same day? |
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COVID-19 counts produced by the CCM provincial system are dynamic and always changing. The time of day that the data are extracted can make a big difference because cases are continually being processed. The Health Department extracts information at 1 p.m. and updates the Data Tracker around 3 p.m., reflecting complete data as of the end of the previous day. The Ministry of Health and Public Health Ontario extract data at different times.
As well, the reporting metric may be different. For example, the "number of new cases" could be the number of cases on a specific reported date, or it could be calculated as the change in the number of cases from the previous day.
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| How are data on COVID-19 cases collected? |
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The Health Department receives notifications of positive COVID-19 laboratory results for Durham Region residents from all Ontario laboratories. These results are received electronically or by fax. Public health units contact residents who are positive to gather detailed information about where they may have acquired COVID-19, their symptoms, who the resident has been in contact with, and demographic information. The information is entered into the provincial database Public Health Case and Contact Management Solution (CCM).
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| How are vaccination data collected? |
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Vaccination data are collected in the provincial reporting system COVaxON. This system is used by all providers administering vaccinations in Ontario, including public health units, hospitals, pharmacies and physicians.
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| Why are hospitalization numbers reported on the Data Tracker different from those reported by Lakeridge Health? |
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The Health Department identifies COVID-19 patients in hospital through various means: the public health nurse speaks directly with the client during the outreach call or to their next of kin, the hospital reports the status to public health, or the public health nurse calls the hospital directly as part of follow-up.
The Data Tracker reports the number of Durham Region residents who have been hospitalized (or that have had their hospital stay extended) because of COVID-19, regardless of where the hospital is located. A case hospitalized for some other reason not related to COVID-19 will not be counted as hospitalized on the Data Tracker. Hospitals report the number of patients in their hospital who have COVID-19, regardless of where the patient lives.
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| How are COVID-19 deaths counted? |
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A COVID-19 death reported on the Data Tracker is a death resulting from a clinically compatible illness in a confirmed COVID-19 case. The number of deaths includes those for which COVID-19 is the underlying cause of death, COVID-19 contributed to but was not the underlying cause of death, and those with type of death listed as unknown or missing. It excludes deaths where the cause of death is unrelated to COVID-19 (e.g., trauma).
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| When is an outbreak declared in an institution? When is it declared over? |
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An institutional outbreak is one that occurs in a long-term care home (LTCH), retirement home (RH) or hospital. Outbreaks in congregate living settings such as group homes and shelters are not counted as institutional outbreaks.
For LTCHs and RHs, a confirmed outbreak is currently defined as two or more residents and/or staff/other visitors in a home (e.g. floor/unit) with a positive COVID-19 test result confirmed by polymerase chain reaction (PCR), rapid molecular test or rapid antigen test with an epidemiological link within a 10-day period. Epidemiological link is defined as reasonable evidence of transmission between residents/staff/visitors and there is a risk of transmission of COVID-19 to residents within the home.
For hospitals, a confirmed outbreak is defined as two or more positive COVID-19 test results confirmed by PCR, rapid molecular test or rapid antigen test in patients and/or staff within a specified area (unit/floor/service) within a 10-day period where both cases have reasonably acquired their infection in the hospital.
Outbreak definitions have changed throughout the pandemic. Prior to April 8, 2021, only one case of COVID-19 occurring in a resident or staff was needed for an outbreak to be declared in a LTCH or RH.
An outbreak is declared over based on the last case identified. When the last case is a resident of an institution, the outbreak is over when no new cases have been identified in the past 10 days since the last case became ill or was isolated. If the last case is a staff member, the outbreak is over when no new cases have been identified in the past 10 days since the last shift the staff worked. The health unit may consider 14 days if there is ongoing transmission and/or evidence of increased severity of illness.
Note that the definitions above are for surveillance purposes only. Public health units have the discretion to declare an outbreak when investigating suspected cases and conditions in institutions, including when the above definitions are not completely met, based on Ministry of Health guidance.
On the Data Tracker, outbreaks are listed in a table on the "Institutional Outbreaks" tab by alphabetical order of institutional name. You can also sort by "reported date" or "date declared over" by clicking on that heading in the table.
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