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Where the numbers come from
Case information data sources
The Public Health Case and Contact Management Solution (CCM) is Ontario's primary disease reporting system. All of Ontario’s Public Health Units report covid 19 case data to CCM for their areas, with the exception of Toronto Public Health which enters data into its own Toronto Public Health Coronavirus Rapid Entry System (CORES). Case data in CORES is added to CCM by Public Health Ontario each day.
With the exception of hospitalization numbers, the covid 19 case data on this page is taken from:
- CCM as of 3:00 p.m. the previous day
- CORES as of 2:00 p.m. the previous day
If there is a discrepancy between numbers reported here and those reported publicly by a Public Health Unit, it is likely because the Public Health Unit hasn’t yet updated their numbers in CCM. In that case, consider the number reported by the Public Health Unit to be the most up to date.
Outbreak setting reporting sources
We create the outbreak graphs and charts from information that facilities report to their local Public Health Unit (which enters it into a reporting tool).
“Outbreak” is defined differently depending on the facility and when the outbreak was reported. The number of outbreaks, and cases per outbreak, may change over time as Public Health Units gather information through their outbreak investigations.
If outbreak data reported here does not match data that other sources have reported to the data catalogue (for example long-term care outbreaks) it is because of different data-collection processes and definitions.
Hospitals report their own data
Hospitals report their own hospitalization numbers to the Ministry of Health, and are usually current as of midnight two days ago.
ICU data is always reported as of 11:59 pm the previous day. This is so patients are not double-counted if they move from one level of care to another within 24 hours.
Hospitalization and ICU numbers are reported for the province and for each Ontario Health Region. Historical data for hospitalizations by region may change over time as hospitals update previously entered data.
Testing data and reporting sources
covid 19 Provincial Diagnostic Network Operations Centre (PDNOC)
We have built a network of health facilities to help manage testing sample collection, transportation, analysis and reporting. This network submits covid 19 lab test information to the covid 19 Provincial Diagnostic Network Operations Centre each day. The most recent data we report on this page reflects provincial testing information from the previous day.
Ontario Laboratories Information System (OLIS)
The Ontario Laboratories Information System contains detailed testing information and results from laboratories across Ontario. We report Ontario Laboratories Information System data using 7-day averages, which help to smooth out day-to-day variation caused by weekend reporting lags and other factors.
We do not show the most recent 7 days of Ontario Laboratories Information System data so labs have time to submit recent results and reduce underreporting. Some underreporting will still happen if:
- labs do not properly report to the system
- health card information is missing
- people do not agree to share their information
Why our numbers and Public Health Unit’s numbers often don’t match
We report covid 19 cases and their status (active, resolved or death) according to the date those cases or status changes happened. That means case numbers for days in the past are continuously being updated as more information is received.
Some organizations use a different approach where case information is reported by the day it is received instead of the day it happened.
Each approach has its own advantages and disadvantages for public reporting. It’s important to be aware of these differences when comparing data between sources.
Another potential reason for reporting differences is the time lag for data entry into the Public Health Case and Contact Management Solution. Some Public Health Units update their own website information immediately, while the Ministry of Health receives the data once a day in the evening. This time lag is usually no more than one day, but means that Public Health Unit data is often the most up-to-date.
Spikes, negative numbers and other data anomalies
Public Health Units continually clean up covid 19 data, correcting for missing or overcounted cases and deaths. These corrections can result in data spikes, negative numbers and current totals being different from previously reported case and death counts.