Infographics: COVID-19 in Alberta by the numbers
Positive, left, and negative COVID-19 antigen rapid tests are picture in Calgary, Alta., Tuesday, Jan. 4, 2022. THE CANADIAN PRESS/Jeff McIntosh
EDMONTON -- Alberta entered 2022 at the start of a fifth pandemic wave, one driven largely by the highly contagious Omicron variant.
Rapidly rising case counts prompted a renewed round of public health measures ahead of Christmas 2021 that included limits on gathering sizes.
At the same time, vaccine uptake continues to grow, including in children who were previously ineligible for shots, as well as in third booster doses.
The combination of more vaccines plus changes to testing eligibility means the prior emphasis on daily case counts and active cases is no longer a priority.
Rather, factors independent of testing including the stress on hospitals, in particular intensive care units, as well as deaths are now better indicators of the impact of the pandemic.
The sections below set out some of the terms and key metrics to monitor as the pandemic continues within that context. Some charts that previously appeared have been removed due to the decreased accuracy and value of case counts.
Follow the links below or scroll down to for the latest on the evolving COVID-19 status in Alberta.
The number of COVID-19 patients in hospitals and intensive care units is an important indicator of how severely the pandemic is affecting Albertans, and the amount of stress it's placing on the province's health care system.
Hospitalization patient counts are a lagging indicator that typically rise a few weeks after an increase in new cases. The numbers include both hospitalized patients who test positive as well as those who are no longer infectious.
The initial patient count on a given day is subsequently revised in coming days for accuracy and to account for reporting delays.
The province's general ICU capacity is 173 beds that are to be used for all patients, not just ones battling COVID-19.
In 2021, more than 82 per cent of COVID-19 hospitalizations were among those either unvaccinated or who had received their first shot within two weeks of diagnosis.
Alberta Health has said the system's capacity to handle COVID-19 patients can be increased to 425 ICU beds, but at the cost of fewer staff and other resources for other patients and procedures, including the cancellation of surgeries.
Vaccines have proven efficient at reducing severe outcomes such as hospitalization or death, particularly among those with two or more doses.
See below to compare hospitalization rates by province.
Deaths are reported daily but a given day's count doesn't necessarily mean all of those deaths happened the day before.
Instead, deaths are reported by the date they occurred and can be attributed several days, or even weeks, prior to being publicly announced.
Alberta Health categorizes coronavirus deaths as where COVID-19 is the cause of death or is a contributing factor unless there is a clear alternative cause of death identified.
Similar to hospitalizations, vaccines have proven effective in drastically reducing the number of deaths among those who have had two or more shots.
COVID-19 vaccines have been distributed in Alberta since late 2020 and became more widely available in 2021. By early 2022, close to 80 per cent of all Albertans had received at least a first dose.
Vaccine efficacy is often expressed as a per cent of new cases, hospitalizations or deaths that are vaccinated (or unvaccinated).
But, that metric doesn't account for the sizable population difference between the number of vaccinated and unvaccinated Albertans.
The above interactive accounts for that disparity by displaying vaccine outcomes by age and vaccination status as a rate per 100,000 people.
See here for an additional interactive showing per cent of population with two doses by age range.
See here for a sortable interactive displaying per cent of population with two doses across Alberta's 132 local geographic areas.
The number of new cases was the most prominent metric for much of the pandemic.
It measures cases confirmed by lab tests as well as probable cases and served as a leading indicator of if COVID-19 transmission was growing or shrinking.
Alberta initially reports new cases the day after they are recorded in the province's health system. The numbers are then subsequently updated in future days as the data is refined for accuracy.
Two factors limit the accuracy of daily case counts.
First, because not all cases of COVID-19 are identified or tested for, the number of announced cases greatly understates the true number of COVID-19 infections.
This undercount is exacerbated by changing testing eligibility that has at times left testing open to only narrow subsets of Albertans.
Second, results from take-home rapid tests are also not included in the province's testing or case count numbers.
The number of active cases represents the number of people currently infectious with COVID-19. The value can go up or down depending on the number of daily new cases and daily new recoveries on a given day.
A recovery is someone who contracted COVID-19 but didn't die due to the virus. It is not synonymous with a return to full health as many "long hauler" patients report severe symptoms after their infections have cleared.
Alberta Health defines a recovery as follows:
- After 14 days from either the time of being tested (confirmed cases) or reported to Alberta Health (probable cases)
- If hospitalized due to COVID-19, anyone who does not require additional hospitalization or treatment in the 10 days after they left the hospital
- If tested, such as a health care worker, two negative tests at least 24 hours apart
The reproduction value, or R-Value, measures the expected number of cases directly caused by one case. It informs if transmission is increasing or decreasing and relies on a number of models that estimate past and future factors.
A value of one means an infected person will infect one other person, on average. A value above one means the spread is growing. A value below one means the spread is slowing.
The province provides the statistics every second week.
Since early April, the province has provided a geographic breakdown of cases for its five health zones, community-level subzones and individual cities.
Alberta Health Services divides the province into five administrative health zones: Calgary, Central, Edmonton, North and South.
The graph above shows the number of active cases per health zone, adjusted to per 100,000 residents. Like all case counts, this data's accuracy is limited by changing testing capacity and eligibility.
A map of those zones can be seen here, and it's important to note that the Edmonton and Calgary zones cover areas significantly bigger than the cities they are named after.
See the vaccination section above for the number of shots and percentage of population immunized by city and local area.
All regions of the province have seen at least one sizable outbreak at some point in the pandemic.
Alberta has been among the top provinces in Canada measured by per capita COVID-19 testing volume since the start of the pandemic.
Test positivity percentage provides insight into what proportion of daily tests are returned with positive results.
It can generally be calculated by dividing the number of positive results by number of tests, but Alberta Health cautions that confirmed cases can appear the reporting system two to three days later. The precise figure takes that delay into account and is provided by the province.
Testing eligibility has changed several times throughout the pandemic, and was limited to a narrow set of groups in January of 2022.
Similar to new cases, test positivity statistics have understated the true number of COVID-19 infections due to testing limits.
Results from take-home rapid tests are not included in the province's testing figures.
Those factors limit the use of test positivity as a leading indicator, and while the exact values don't hold the meaning they once did, test positivity still provides a relative indicator if transmission is growing or shrinking.
The above interactive graphic shows total and population adjusted numbers for COVID-19 hospitalizations, patients in intensive care units, deaths and vaccinations across Canada's provinces and territories.
Note, hospitalizations are measured differently across some provinces, and regular hospitalization data is not regularly available for territories.