Infographics: COVID-19 in Alberta by the numbers
A passenger awaits her flight at the Calgary Airport in Calgary, Alta., Friday, Oct. 30, 2020, amid a worldwide COVID-19 pandemic. THE CANADIAN PRESS/Jeff McIntosh
EDMONTON -- The fourth wave of the COVID-19 pandemic hit Alberta hard, prompting renewed public health measures and pandemic-high patient counts in hospital and intensive care units.
The number of vaccinated Albertans is expected to grow rapidly after Health Canada authorized Pfizer-BioNTech’s two-dose vaccine for children ages five to 11.
But experts fear the continued presence of the Delta variant, along with more indoor gatherings amid colder winter weather, could lead to a fifth wave in Alberta.
The sections below set out some of the terms and key metrics to monitor as the pandemic continues.
Follow the links below or scroll down to for the lastest on the evolving COVID-19 status in Alberta.
HOSPITALIZATIONS AND DEATHS
The numbers of COVID-19 patients in hospitals and intensive care units are important indicators of how severely the pandemic is affecting Albertans, and the amount of stress it's placing on the province's health care system.
The number of hospitalizations is a lagging indicator that rises a few weeks after an increase in new cases.
A sizable majority of COVID-19 patients in Alberta hospitals and intensive care units is unvaccinated. Rates adjusted for the higher number of vaccinated versus unvaccinated Albertans echo a similar message: vaccines greatly reduce severe outcomes among COVID-19 patients.
The province's general ICU capacity of 173 beds that are used for all patients, not just ones battling COVID-19.
Elderly age groups had seen the highest rate of hospitalization throughout most of the pandemic. But during the fourth wave, younger Albertans have been more likely to be hospitalized.
More than 88 per cent of hospitalizations due to COVID-19 in 2021 have been among those either unvaccinated or who 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.
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.
COVID-19 vaccinations promise a way out of the pandemic in time.
Vaccines have been distributed in Alberta since late 2020 with the number of shots given out increasing through the early part of 2021.
Most vaccines require a second shot, and possibly a further booster shot months or years later to ensure continued immunity.
Alberta began rolling out its vaccination plan in late 2020. By January 2021, Albertans over the age of 75 were eligibile to book a shot.
Vaccine eligiblity has grown from mid-March onwards and expanded to all Albertans born in 2009 or earlier on May 10. On Nov. 19, Health Canada authorized the Pfizer-BioNTech's two-dose vaccine for children aged five to 11 years old.
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 represents the number of patients who are newly infected with the coronavirus and are considered to be a leading indicator of how COVID-19 is spreading.
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.
The number of active cases represents the number of people currently infectious with COVID-19. The value can 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:
- A return to health after 14 days of isolation for those with COVID-19 but who experienced only mild symptoms.
- 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 cases are increasing or decreasing and relies on a number of models that estimate past and future factors.
The value can be calculated using different models all of which estimate a number of past and future factors around the virus and population.
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.
CITIES AND REGIONS
Since early April, the province has provided a geographic breakdown of cases for its five health zones, community-level subzones and individual cities.
- Infographics: COVID-19 cases in Calgary
- COVID-19 in Edmonton: Numbers broken down by neighbourhood
- Interactive map: COVID-19 case status in Edmonton communities
Alberta Health Services divides the province into five administrative health zones: Calgary, Central, Edmonton, North and South.
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.
Variants occur when a virus develops a set of mutations that change its genetic code enough that it reacts differently than the original strain, but also not enough that it becomes its own virus.
A series of variants that developed in late 2020 drew particular concern due to being more transmissible, and in some cases more deadly, than the initial strain.
- What are the different COVID-19 variants and why do they matter?
- COVID-19 variant tracker: cases by province and territory
- What you need to know about COVID-19 variants in Canada
These variants are identified by the location of their discovery or through letters and numbers, but efforts have been made to rename them to avoid stigmatizing entire cities and countries.
Confirmed COVID-19 cases had been screened for variants since Feb. 1, 2021 and after June 1, 2021, with only a sample of cases been screened during the month of May due to high case counts.
Alberta Health notes the need for a second screening delays the reporting of variant cases by up to two days, though delays in other provinces are often much longer.
On April 11, Alberta Health data showed that for the first time, variants made up a majority of the province's active COVID-19 cases.
The B.1.617 Delta variant has been of particular concern with doctors warning it is more transmissible, more deadly and more resistant to vaccines than other strains of COVID-19.
Alberta Health has said variants have become, and will continue to be, the dominant strain in Alberta, meaning that every new case should be assumed to be a variant.
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 canappear the reporting system two to three days later. The precise figure takes that delay into account and is provided by the province.
Since July 29, testing has been recommended only for symptomatic Albertans.
The above heat map displays active cases by age range, with darker shading representing more active infections.
Age ranges make up drastically different proportions of Alberta's population so the above chart displays active case rates adjusted to those population sizes.
Since the onset of the pandemic, COVID-19 has affected the elderly more than other age groups as seen by comparably higher hospitalization and death rates. Vaccine distribution focused on the province's elderly population has helped slow that trend by spring of 2021.
Deaths have skewed heavily towards the elderly population, particularly in the first and second wave. Vaccinations helped temper this trend by the spring of 2021 where cases and deaths moved towards younger demographics
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.