COVID-19 

Data sources

• Halton case data: Public Health Case and Contact Management (CCM) Solution, extracted Thursday mornings to reflect cases reported by end of the previous day.
• Halton test volume and percent positivity data:  Ministry of Health, SAS Visual Analytics Tool, COVID-19 Testing reports, extracted Thursdays.
• Halton hospital data: Ministry of Health, SAS Visual Analytics Tool, COVID Regional Hospital and Hospital Utilization reports, extracted Thursdays.
• Halton vaccination data: IntelliHealth, COVax package, extracted Thursday mornings to reflect immunizations administered by end of the previous day.
• Vaccine coverage denominators: Institute for Clinical Evaluative Sciences, Applied Health Research Question #2021 0950 080 000.

General

• Numbers should not be expected to match numbers reported by other sources, due to different data extraction times.
• All data are dynamic and subject to change with future updates.
  • CCM and COVax are dynamic reporting systems that allow ongoing updates to data previously entered.
  • As a result, data extracted from CCM and COVax represent a snapshot at the time of extraction and may differ from previous or subsequent reports.
  • Data are updated Thursdays. Numbers update dynamically within the dashboard by 4 pm on Thursdays as server times allow.
  • Based on information gathered while doing case investigation, numbers may increase or decrease to reflect our most up to date information. Numbers may change significantly when data cleaning initiatives are completed.
• All data except data shown in the “Halton Hospitals” tab includes only individuals whose main usual residence is in Halton Region. Cases who have municipality information pending are excluded.
• As of January 1, 2022, probable cases are no longer included in total case counts due to changes in testing and case management necessitated by the Omicron surge. Prior to 2022, probable cases were individuals presumed to have COVID-19 because they had symptoms of COVID-19 and were travelers returning from an affected area, had close contact with a confirmed case, lived/worked in a facility experiencing a COVID-19 outbreak, had indeterminate test results, or had a preliminary positive result from a Health Canada approved point-of-care assay (rapid COVID-19 test).
• The 7-day moving average of number of cases should not be considered exactly equivalent to the unique number of individuals in Halton who have been diagnosed with COVID-19, because there are some individuals who are counted more than once because they are confirmed reinfection cases. A confirmed reinfection case is a person who has tested positive for COVID-19 more than once, with time-based or test-based clearance between the multiple infections.

Vaccinations

• Data on the “Doses administered in Halton” subtab are representative of doses administered anywhere in Halton Region, including community and hospital-based clinics run by Halton Region Public Health, Halton Healthcare, Joseph Brant Hospital, or other partners on a pop-up basis; other clinic settings run by the Halton Region Health Department (which includes Halton Region Public Health and Halton Region Paramedic Services) and other partners; pharmacies; and physicians’ offices.
• Data on the “Doses administered in Halton” subtab include primary series (first and second doses), and additional doses, and should therefore not be interpreted as the unique number of individuals vaccinated. These data include doses administered to non-Halton residents (e.g. staff who work at a Halton facility but live outside Halton), and do not include any doses Halton residents may have received outside Halton (e.g. Halton residents who work at facilities outside Halton and were vaccinated there).
• Data on the “Doses administered in Halton” subtab reports doses administered by age at time of first dose and includes individuals without a known age at time of vaccination (pending data cleaning). Data on the “Vaccine coverage in Halton residents” subtab assigns residents to an age category based on age at time of data extraction from Intellihealth (Thursdays) and excludes individuals without a known age, as known age is required to calculate vaccine coverage. Children 0-6 months of age are included in denominators used to calculate coverage estimates. However, children 0-6 months of age are not eligible for COVID-19 vaccination, and therefore, are not included in the numerator. 
• Data on the “Vaccine coverage in Halton residents” subtab reflects Halton residents, rather than doses. It includes all Halton residents who have had at least a completed primary series of doses (one-dose and two-dose coverage). It also shows a subset of these individuals who have had at least one booster dose, separately shown according to whether the most recent booster dose was given in the last 6 months, or 6 or more months ago. It includes known Halton residents who were immunized in Halton, as well as Halton residents who received a primary series and/or a booster dose outside Halton, if the dose was recorded in COVax. A second dose is considered valid if it was not given earlier than the product monograph recommends for the specified vaccine product. A booster dose is considered valid if it was not given earlier than the minimum interval of 28 days from the second dose or any previous booster dose. Only residents alive on September 1, 2022 are included in coverage estimates.
• Vaccine coverage is shown by completed primary series, booster doses given less than 6 months ago, and doses given 6 or more months ago.  The percentages of residents receiving a booster in these timeframes are subsets of the total percentage of residents who completed a primary series, since completing a primary series is a prerequisite to receiving a booster.
• Vaccine coverage is calculated for the population aged 18 and up, 12 and up, 5 and up, and for the total population across all age groups (0+). Booster dose coverage is calculated for the population aged 5 and up. 
• All individuals who initiated their primary series with Pfizer-BioNTech (3 mcg) between 6 months old to 4 years old must have received three doses of vaccine to be considered to have completed their primary series.
• Vaccine coverage is calculated using September 2022 Halton Region population estimates provided by ICES based on the Registered Persons Database.
  • Population estimates reflect the postal codes associated with health cards, and therefore are subject to error.
• For individuals aged less than 65 years of age, individuals who did not have any contact with the Ontario health care system in the last 9 years have been excluded; for individuals aged 65+, individuals who did not have any contact with the Ontario health care system in the last 3 years have been excluded. These individuals were excluded as they likely are not living in the province.
• Vaccine coverage by Forward Sortation Area (FSA) is available on the ICES COVID-19 Dashboard (external link) under the “Vaccine Coverage in Ontario” heading. FSA is the first three characters of a postal code. The following FSAs are in Halton Region: L0P, L6H, L6J, L6K, L6L, L6M, L7G, L7J, L7L, L7M, L7N, L7P, L7R, L7S, L7T, L9E, L9T.
• Data from COVax are subject to misclassification, as assignment to a health unit of residency is dependent on the postal code entered but can be overwritten, and new postal codes may not be correctly assigned by the system. Halton residents may be misclassified as non-Halton residents and therefore not included in the coverage estimates, and conversely, some non-Halton residents could be erroneously classified as Halton residents depending on the address provided or edits to the health unit field by the immunizer. This is especially true when Halton residents with a newer postal code are immunized outside Halton. Due to these concerns, wherever possible, health unit residency has been assigned outside the system on the basis of postal code and municipality entered into COVax using an updated postal code lookup maintained by Halton Region Public Health. Therefore, individuals with a Halton municipality or postal code in COVax but entered with a different client health unit are assumed to actually be Halton residents; and individuals without a Halton municipality or postal code but entered with a client health unit of Halton are assumed to actually be non-Halton residents. If health unit is missing in COVax, but the reason for immunization involves being a resident of a facility in Halton, the individual is assumed to be a Halton resident.

Snapshot

• “New COVID-19 cases, 7-day moving average” indicator
  • Reported date, used for this indicator, is the date the case was reported to public health. This does not represent the day the case was first publicly reported in the dashboard, and there may be delays between when the case is reported to public health and when it appears in the dashboard (e.g., due to time required to receive confirmatory lab results, or receive a case referral from another health unit). Interpret trends with caution, as information-gathering and data entry is ongoing for recently reported cases.
  • After December 31, 2021, case counts no longer reflect the true number of COVID-19 infections in Halton Region as confirmatory testing is focused on high-risk settings and individuals only.
• “Number of active institutional outbreaks” indicator
  • Outbreaks are declared when the appropriate provincial definition is met. Provincial definitions for outbreaks vary by type of outbreak.
• “Percent positivity” indicator
  • Percent positivity data are updated Thursday to reflect the past seven days of complete data. Due to the time required for processing of specimens, reporting will be delayed by seven days to allow for the lag time between specimen collection and reporting of results.
  • Percent positivity is calculated as the total number of positive tests over the 7-day period ending in the specified date, divided by the total numbers of tests conducted over that 7-day period.
  • Percent positivity data reflects only lab tests that have been assigned to Halton Region based on Forward Sortation Areas located within Halton. There are several considerations associated with these data:
    • The unit of analysis is the number of tests completed. Individuals may have more than one test conducted, and each test will be counted.
    • The COVID-19 test results are captured in the Ontario Laboratories Information System (OLIS). The testing date represents the date of specimen collection. Unconsented test results are excluded.
    • The location of tested individuals was based upon the test recipient’s postal code (and corresponding health unit). New postal codes issued in the last year are excluded as the postal code file is only updated once per year. These address assignments can lead to misclassification of the health unit.
• “Number of Halton treatment plants with increasing trend greater than 10% per day in wastewater signal” indicator
  • The trend in wastewater signal may still be relatively high, but may not necessarily be increasing (signal must meet a threshold of a 10% change in the 7-day moving average). There is lag time required to collect, process and analyze the samples which limits our ability to use these data to identify changes in community transmission as it occurs.
• “Number of patients in Halton hospitals for COVID-19” and “Number of patients in Halton hospitals with COVID-19” indicators
  • As of December 29, 2021 hospitals began reporting patients hospitalized for COVID-19 and those with COVID-19. Prior to this, the data represent any COVID-19 positive patient hospitalized in a Halton hospital, regardless of the reason for hospitalization.
    • Hospitalizations for COVID-19 include confirmed cases of COVID-19 who are admitted to the hospital and are actively being treated for their COVID-19 infection and its symptoms or have had their hospitalization prolonged due to their COVID-19 diagnosis.
    • Hospitalizations with COVID-19 include confirmed cases of COVID-19 who are admitted to the hospital for reasons other than COVID-19, but test positive upon admission or during their hospital stay.
  • Individuals with COVID-19 who are in Joseph Brant’s Pandemic Response Unit will be included in the counts.
  • Individuals who visited the emergency room but who were not admitted to hospital are not included.
  • Individuals who are admitted to Halton hospitals may not be Halton residents, and conversely, Halton residents may be hospitalized in hospitals outside Halton. Therefore, the counts of COVID-19 patients in hospital may not always include the same individuals represented as cases elsewhere in the dashboard, which focuses on Halton residents only.
• For more information on the monitoring indicators, please see the technical notes (PDF file).

Wastewater

• As of April 2023, two wastewater treatment plants in Halton Region (the Mid-Halton treatment plant and the Skyway treatment plant) are sampled multiple times per week for COVID-19 testing.
• Sampling, testing and analyses are completed in collaboration with the University of Toronto, the University of Guelph and the Ontario Ministry of the Environment, Conservation & Parks (MECP).
• Data will be updated once per week. The update is dependent on the timing of sampling, testing and analysis in collaboration with project partners.