COVID-19 epidemiology update: Cases following vaccination:
- Last updated: 2023-01-26
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Summary of COVID-19 cases, hospitalizations and deaths, cases following vaccination, testing and variants of concern across Canada and over time. Older versions of this report are available on the archived reports page.
We are in the process of improving this page. Regular data updates will resume in the coming weeks. Data extracted on for cases between December 14, 2020 and .
While COVID-19 vaccines are highly effective at preventing severe outcomes such as hospitalization and death, vaccinated people can still get infected if exposed. This means that even with high vaccine effectiveness, some vaccinated people will get sick, be hospitalized or die.
Most people in Canada have been vaccinated. Because they’re a larger group, there will naturally be more cases among vaccinated people than among unvaccinated people. However, despite their higher case counts, vaccinated people are less likely to get very sick or die.
Case counts underestimate the total number of COVID-19 cases because a rapid increase in cases starting in December 2021 led to changes in COVID-19 testing policies and delays in data entry.
Case counts are likely to over-represent people at risk of severe disease, because they have been prioritized for testing. Data should be interpreted with caution.
Cases reported since the start of the vaccination campaign, as of July 03, 2021
The vaccination campaign began on December 14, 2020. Since then, we've received case-level vaccine history data for 75.5% (n=624,980) of known COVID-19 cases aged 5 and older.
Of these cases:
- () were unvaccinated
- () had completed their primary vaccine series
- () had completed their primary vaccine series and 1 additional dose
- () had completed their primary vaccine series and 2 or more additional doses
For definitions of the different vaccination statuses, please refer to the Technical notes and definitions section.
Figure 1. of outcomes of confirmed COVID-19 cases reported to PHAC by vaccination status as of July 10, 2021
Figure 1: Text description
July 10, 2021.
Cases following vaccination were more common among older adults and females (Table 1). This may be due to:
- higher risk of disease among older adults and pregnant people
- longer life expectancy among females, which means more women move into older age groups with a higher risk of disease
Older adults have been prioritized for second booster doses. As a result, older people make up a large proportion of people who had completed their primary vaccine series and 2 or more additional doses. For the same reason, they also make up a large proportion of cases in that group.
- Source: Detailed case information received by PHAC from provinces and territories, since December 14, 2020 (see data notes in the Technical notes and definitions section)
People who were diagnosed with COVID-19 after completing their primary vaccine series were significantly less likely to be hospitalized or to die, particularly if they received an additional dose(s).
Between and , unvaccinated cases were times more likely to be hospitalized and times more likely to die from their illness, compared to cases with a completed primary vaccine series. During the same 4-week period, unvaccinated cases were times more likely to be hospitalized and times more likely to die from their illness, compared to cases with a completed primary vaccine series and 1 or more additional doses (see data notes in Technical notes and definitions section).
Technical notes and definitions
Data for this analysis comes from the COVID-19 national data set, which contains detailed case-level information received by PHAC from all provinces and territories.
Data notes for Table 1
- 12 of 13 provinces and territories have reported case-level vaccine history data to PHAC as part of the national COVID-19 dataset.
- of these provinces and territories reported data on cases with a completed primary vaccine series and 1 additional dose. of the 12 provinces and territories reported data on cases with a completed primary vaccine series and 2 or more additional doses. In provinces and territories that have not yet reported additional dose data, cases are classified as having completed their primary vaccine series if they have a completed primary series or with or without any more additional doses.
- We used a data cut-off of to account for routine reporting delays associated with vaccine history information.
- †Counts of cases by vaccination status may not add up to total counts, as data on cases not yet protected and partially vaccinated cases are not presented here.
- Data presented here on cases with a completed primary vaccine series and 1 or more additional dose(s) are limited to individuals aged 5 years or older.
- *When available, we used gender data. If unavailable, we used sex data. We excluded cases with missing gender and sex data from the gender analysis. Reliable data on gender diverse respondents are unavailable due to small counts.
Data notes for 4-week age standardized rate ratios
- As of October 18, 2022, rate ratios are age-standardized using July 2022 Canadian population estimates for all 2022 report weeks. As a result, there is a decrease in rate ratios compared to previously published reports. For more information on denominators for cases following vaccination, see Vaccination coverage data sources.
- For analyses of rate ratios, cases are classified as having completed their primary series with one or more additional dose(s) if they have received at least 1 additional dose after completing their primary series
- Rate ratio calculations were based on data from provinces and territories that have reported complete case-level vaccine history data to PHAC during the 4-week period of analysis.
Vaccine status definitions
Episode date: Refers to symptom onset date. When symptom onset date is unavailable or the case is asymptomatic, episode date refers to either:
- laboratory specimen collection date, or
- laboratory testing date
PHAC monitors cases following vaccination using the following categories:
- Unvaccinated cases: those who were unvaccinated at the time of their episode date.
- Cases not yet protected from vaccination: those whose episode date occurred less than 14 days after their first dose of the vaccine.
- Partially vaccinated cases: those whose episode date occurred:
- 14 days or more after their first vaccine dose in a 2-dose series, or
- less than 14 days after their second dose of the vaccine.
- Cases with a completed primary series: those whose episode date occurred:
- 14 days or more after receipt of a second dose in a 2-dose series, or
- 14 days or more after receipt of one dose of a 1-dose vaccine series, and
- if an additional (for example, third dose or booster) dose was received, 0 to <14 days after receipt of the first additional dose.
- Cases with a completed primary series and 1 or more additional dose(s): those whose episode date occurred 14 days or more following the receipt of at least 1 additional dose (for example, third dose or booster) of a COVID-19 vaccine product, after completing a primary vaccine series.
- Data on counts and distributions are further categorized into 2 groups:
- Cases with a completed primary vaccine series and 1 additional dose: those whose episode date occurred 14 days or more following receipt of 1 additional dose (for example, third dose or first booster) of a COVID-19 vaccine product and, if a second additional dose was received, 0 to <14 days after receipt of that dose
- Cases with a completed primary series and 2 or more additional doses: those whose episode date occurred 14 days or more following receipt of at least 2 additional doses (for example, fourth dose or second booster)
- Data on counts and distributions are further categorized into 2 groups:
- COVID-19 vaccine product: vaccines that have been:
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