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COVID-19 vaccine safety in Canada

This page provides information about any adverse events following immunization (AEFI) that individuals have reported after receiving a COVID-19 vaccine in Canada. Even though an adverse event is reported, it is not necessarily related to the vaccine. We update this page every Friday at 12:00 PM Eastern Time.

On this page

What you need to know up to and including MMM DD, 2021

No safety signals

(potential safety issues) have been identified

{New AEFIs reported since last report}

New AEFI reports since last update

({New non-serious AEFIs} new non-serious and {New serious AEFIs} new serious)

{Total AEFIs}

Total AEFI reports

({Percent non-serious (total)}% of all doses administered)

{Total non-serious AEFIs}

Total AEFI reports were non-serious

({Percent non-serious (total)}% of all doses administered)

{Total serious AEFIs}

Total AEFI reports were serious

({Percent serious (total)}% of all doses administered)

{Total doses administered}

Total doses administered as of


Adverse Event Following Immunization (AEFI)

An AEFI is any untoward medical occurrence which follows immunization. It isn’t necessarily causally related to the usage of the vaccine. The adverse event may be any:

For more information, please refer to the Council for International Organizations of Medical Sciences (CIOMS) and World Health Organization (WHO). Definition and Application of Terms for Vaccine Pharmacovigilance. Report of CIOMS/WHO Working group on Vaccine Pharmacovigilance. Geneva: CIOMS and WHO; 2012

AEFI report

Please note that one AEFI report, which represents one person, may report on more than one symptom (i.e a serious or non serious adverse event following immunization, or AEFI).

Serious AEFI

An event is considered serious if it:

Medically important event

An event which may not be immediately life-threatening but requires intervention to prevent one of the outcomes listed above and may also be considered as serious. This is based on the International Council on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use. See:

International Council on Harmonisation (ICH). Support Documentation. Medical Dictionary for Regulatory Activities.

Adverse Events of Special Interest (AESI)

This is a pre-specified medically significant event that has the potential to be causally associated with a vaccine product. It must be carefully monitored and confirmed by further special studies.

For more information, please refer to World Health Organization. COVID-19 Vaccines: Safety Surveillance Manual.
Safety signal

Information indicating a new and potentially causal association between a vaccine and an event that could affect health. The event is either unknown or incompletely documented. It could also indicate a new aspect of a known association. The primary purpose of vaccine post-market surveillance is to detect safety concerns. These concerns include a possible increase in the severity or frequency of expected AEFIs, or one or more unexpected events (i.e., an event that is not consistent with Canadian product information or labelling).

For more information, please refer to World Health Organization: Investigation of safety signals.

Summary of AEFI reports

The information on this page reflects detailed case information data from the Public Health Agency of Canada’s Canadian Adverse Events Following Immunization Surveillance System and Health Canada’s Canada Vigilance program. The data may undergo changes as more information about cases becomes available.

There have been AEFI reports up to and including , of which were considered serious. The weekly and total numbers of AEFI reports are shown in Figure 1.

Figure 1. number of COVID-19 vaccine AEFI reports up to and including MMM DD, 2021 (n=)

Figure 1: Text Description
Number of COVID-19 vaccine AEFI reports up to and including (n=)
Week report received Weekly non-serious AEFI reports Weekly serious AEFI reports Total non-serious AEFI reports Total serious AEFI reports

AEFI reports by age and sex

Among people where age was known, those aged years reported the most AEFIs (Figure 2). Most of the AEFI reports involved where sex was known (Figure 2), up to and including .

Figure 2. AEFI reports by up to and including MMM DD, 2021 (n=)

Figure 2: Text Description
AEFI reports by age group and sex up to and including (n=)
Age group Total AEFI reports Male Female Other Unknown

Serious and non-serious adverse events reported

Figure 4. Classification of serious AEFIs as of MMM DD, 2021

Data notes

The data presented in this report are estimates and may not accurately represent national COVID-19 vaccine AEFIs for the following reasons:

  1. There may be delays in receiving reporting forms. These delays may be due to jurisdictions investigating and reviewing each AEFI prior to submitting the information to PHAC. There are also limitations to reporting practices such as underreporting, missing information, and differing AEFI reporting practices accross jurisdictions in Canada.
  2. Information is collected on individuals for whom an AEFI report was submitted, not on the total number of individuals who experience an adverse event as not every adverse event is reported.
  3. New information contained in this report is not comprehensive but rather represents preliminary results of data received on a weekly basis.
  4. Note that reporting jurisdictions may refer to gender as opposed to sex.

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