COVID-19 Vaccine Safety Surveillance in Ontario


8 June 2021

As with any new vaccine, it is understandable that people might have questions about the safety of COVID-19 vaccines and potential adverse events following immunization (AEFIs). This post will explore COVID-19 vaccine safety surveillance in Ontario, what adverse events following immunization are and how they are monitored, and PHO’s role in monitoring vaccine safety.

About Vaccine Safety Surveillance

What is vaccine safety surveillance?

Vaccine safety surveillance (also called vaccine safety monitoring) is essential to the success of immunization programs and maintaining public confidence in vaccines. Vaccines are thoroughly reviewed for efficacy and safety before they are authorized for use and are continually monitored to ensure their safety. Local, provincial and federal health authorities work together to ensure COVID-19 vaccines approved for use in Canada remain safe and effective.

What are AEFIs?
An AEFI is an unwanted or unexpected health effect that happens after someone receives a vaccine, which may or may not be caused by the vaccine. Some examples of AEFIs that may be reported are: injection site reaction, rash or allergic events.

COVID-19 Vaccine Safety Surveillance in Canada

Canada has a comprehensive system in place for monitoring AEFIs for all vaccines, including the COVID-19 vaccine, which operates through federal and provincial health partners and includes:

  • The Canadian Adverse Event Following Immunization Surveillance System (CAEFISS) - a surveillance system led by the Public Health Agency of Canada (PHAC) that tracks AEFIs reported from provincial and territorial public health authorities.
  • Health Canada - receives reports of AEFIs submitted directly to vaccine manufacturers.

Additional methods of national vaccine safety surveillance include directly asking people who have had the vaccine if they have experience any AEFIs or scanning for adverse events in clinical or administrative records ( also called active surveillance). In Canada, active surveillance programs for vaccine safety include:

  • The Canadian Vaccine Safety (CANVAS) Network - a national network of sites across Canada that collects information on adverse events during implementation of immunization campaigns (e.g.,COVID-19 vaccine safety study).

COVID-19 Vaccine Safety Surveillance in Ontario

The goal of vaccine safety surveillance in Ontario is early detection and timely response to real or perceived vaccine safety issues. Ontario’s vaccine safety surveillance process provides important information to support and inform immunization program planning and evaluation. Provincial vaccine safety surveillance not only includes the identification and investigation of serious or unexpected occurrences of AEFIs, it also involves capturing vital data, in order to estimate provincial rates of reported AEFIs by vaccine, as well as sharing vaccine safety information with stakeholders, which is essential in maintaining public confidence in vaccine programs.

Reporting AEFIs for COVID-19 in Ontario
In Ontario, vaccine safety surveillance relies on the reporting of AEFIs by health care providers, vaccine recipients or their caregivers to their local public health unit (PHU). AEFI reports received by PHUs are investigated, assessed and reported in the provincial surveillance system.

PHO’s Role in COVID-19 Vaccine Safety Surveillance

PHO leads provincial vaccine safety surveillance including analysis and reporting on provincial AEFI data, participating in national vaccine safety networks, supporting local PHUs with AEFI reporting and producing vaccine safety resources for PHUs and healthcare providers.

Surveillance Data and Reporting
Conducting provincial COVID-19 vaccine safety surveillance at PHO involves various processes. One process includes the daily monitoring and review of AEFIs reported by PHUs via the Case and Contact Management System (CCM), which is a central data repository for Ontario COVID-19 reporting. In addition, each week PHO also produces an epidemiological summary of COVID-19 AEFIs reported in Ontario. The team also extracts and transmits AEFI data weekly to PHAC for inclusion in CAEFISS.

Quick Facts AEFIs for COVID-19 in Ontario

  • More than 5.3 million doses of COVID-19 vaccines have been administered in Ontario, as of May 1, 2021.
  • Only 0.04% (2,280) of all COVID-19 vaccines administered in Ontario had AEFIs reported, based on information received by Public Health Ontario over the same period.
  • Serious events (i.e., those requiring hospitalization) were rare and represent 0.001% of all COVID-19 vaccines administered in Ontario.
  • The two most commonly reported adverse events for COVID-19 AEFIs received to date are allergic skin reactions and injection site reactions (i.e., pain, redness and swelling at the injection site). These two reaction types represent a little more than half (53%) of all AEFI reports received to date in the province.

Vaccine Safety Networks and Partnerships

Nationally, PHO participates in a Canadian vaccine safety network, led by PHAC, which monitors vaccine safety and identifies potential issues for further investigation. This group has representation from federal/provincial/territorial immunization programs across the country as well as other public health partners. 

“PHO participates in the national vaccine safety working group, which has representation from immunization programs of the provinces and territories across the country as well as Health Canada. This collaboration has been crucial during the COVID-19 pandemic as information is rapidly evolving so it provides a platform for timely sharing of information across the country.”

— Chi Yon Seo, Epidemiologist Lead, Public Health Ontario

On a local level, PHO provides support and advice to PHUs managing complex AEFIs and develops resources for PHUs. These resources support PHUs in investigating and reporting COVID-19 vaccine AEFIs, which is vital to bolstering the quality of vaccine safety surveillance data.

“Reporting of AEFIs is critical for the ongoing monitoring of the vaccine safety and is particularly important for a new vaccine program. PHO has been developing resources that public health units and health care providers can use to assist with investigating and reporting adverse events.”

— Sarah Alley, Nurse Consultant, Public Health Ontario

Vaccine Safety Surveillance Resources

PHO also generates a significant number of resources related to vaccine safety for various stakeholders.

This post provides a general overview of AEFIs within the context of COVID-19 vaccination. We encourage individuals to consult PHO’s COVID-19 vaccine page or their local public health unit for further information on vaccine safety surveillance and AEFI reporting.

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Updated 8 June 2021