CPHO Sunday Edition: Vaccine safety in Canada: What you should know


The CPHO Sunday Edition

March 28, 2021 | Ottawa, ON | Public Health Agency of Canada

The COVID-19 pandemic continues to create stress and anxiety for many Canadians, particularly those who do not have ready access to their regular support networks. Through the Wellness Together Canada online portal, people of all ages across the country can access immediate, free and confidential mental health and substance use supports, 24 hours a day, seven days a week.

It has been yet another productive week on the vaccine front in Canada, as close to 1.4 million doses of COVID-19 vaccines arrived in Canada, and roll-out continues to ramp up across the country. It seems fitting that as the first signs of spring emerge around us, and the days get longer, there is more hope and optimism to fill the air. Our vaccination program is moving forward, to a point that the majority of us now have someone close to us who has been vaccinated. It is an incredible feeling to know that a loved one who is at higher risk for COVID-19 is now safer.

Through this process, we are also learning many new things about vaccines. However, with so much information coming at us, and much of it evolving at a rapid pace, this can also create gaps in our understanding, cause confusion, and even, in some cases, lead to distrust.

I know that many of you are curious to know more about vaccine safety and how adverse events following immunization (AEFIs) are monitored in Canada. That is why, in today's Sunday Edition, I would like to explore this process by providing you with a bird's eye view of the vaccine safety monitoring process from vaccine development through to post-marketing surveillance.

Ensuring Vaccine Safety at Every Step of the Vaccine Life Cycle

Vaccine safety assessment and monitoring is not something that takes place in a single, fixed step. Rather, it is an ongoing and continual process that is carried out throughout a vaccine's life cycle, spanning all phases from development, to market authorization, administration, and post-marketing surveillance.

Here is brief description of how safety (and effectiveness) are evaluated at each step of the vaccine life cycle:

Pre-approval review and approval process

Vaccine testing starts in the lab with preclinical studies, which are carried out using cell cultures (in vitro studies) and animal models (in vivo studies). These studies provide preliminary information on vaccine effectiveness and safety.

If the vaccine is shown to be safe and effective in the lab and in animals, studies in people, known as clinical trials, are conducted next. These assess safety, including safe dose range, and efficacy, starting with a small number of healthy volunteers, and moving up to 1,000 or more participants by phase 3 trials. Importantly, every AEFI noted in these studies is investigated carefully and assessed to determine whether the vaccine is the cause.

In order for a manufacturer to receive regulatory approval for a new vaccine, they are required to submit all preclinical, clinical and manufacturing data to the Biologic and Radiopharmaceutical Drugs Directorate, the group responsible for approving vaccines at Health Canada, for their own independent review. Scientific and medical reviewers from this group then conduct an in-depth assessment of all the data they receive. A vaccine is only authorized for use in Canada if it meets the regulatory requirements for safety, efficacy, and quality set by Health Canada.

Quality Control

The Biologic and Radiopharmaceutical Drugs Directorate will also review detailed chemistry and manufacturing information to ensure consistent quality of the vaccine product, which is another important facet related to safety. This may include an on-site evaluation of the manufacturing process, as well as a lot release program, which tests vaccine samples from different lots. Vaccine manufacturers must also adhere to current Good Manufacturing Practices (GMP), or recognized international quality standards, a process which is ensured by Health Canada's Regulatory Operations and Enforcement Branch.

Post-approval monitoring

Once a vaccine is approved, it continues to be monitored and any safety signals are investigated. Canada has a strong vaccine safety monitoring system that remains in place for as long as the vaccine is used. Health Canada and the Public Health Agency of Canada (PHAC) share the responsibility for ongoing monitoring in collaboration with provincial, territorial and local public health authorities, health care professionals, vaccine manufacturers, and the public. This ongoing process is important as it alerts public health authorities to changing trends or unusual AEFIs that were not previously reported. These are adverse events that occur too rarely to be detected even in a large clinical trial; they can only be identified once millions of people receive a vaccine. This is why when serious, unusual or unexpected AEFIs occur, they need to be taken very seriously and investigated very carefully, in order to determine whether they are indicative of a safety issue related to the vaccine that has emerged unexpectedly.

Manufacturers are also required to report AEFIs that they become aware of in Canada, or internationally, to the Canada Vigilance Program, Health Canada's post-market surveillance program that collects and assesses reports of suspected adverse reactions to health products marketed in Canada. As part of a "risk management plan", manufacturers may also be required to provide data on the safety of the vaccine for specific groups of people or conduct additional studies.

Canada also has several other post-market vaccine safety surveillance systems in place to detect any serious adverse events that may occur following immunization. These include the Canadian Adverse Events Following Immunization Surveillance System (CAEFISS), a federal, provincial and territorial collaborative surveillance system that is supported by PHAC. CAEFISS continuously monitors the safety of vaccines in Canada through various reporting processes. Health care professionals are asked to report all serious adverse reactions, such as those that may require hospitalization, result in persistent or significant disability or incapacity or be life-threatening, to CAEFISS. Anyone who experiences an adverse event is encouraged to inform their healthcare professional so they can report it.

Another component of the vaccine safety surveillance system involves proactively inquiring about adverse events from vaccine recipients or searching adverse events in clinical or administrative records. The Canadian Vaccine Safety Network (CANVAS) is a national network of sites across Canada that conducts vaccine safety surveillance during implementation of immunization campaigns. It can provide rapid information early on in vaccination campaigns, including for COVID-19. CANVAS is currently conducting a large, national, web-based vaccine safety study to monitor health events that may occur after COVID-19 vaccinations.

Approaches used in Canada align with good practices put forward by the World Health Organization in their COVID-19 vaccine Safety Surveillance Manual. If any serious side effects are identified, an investigation will take place and this information will be rapidly communicated to Canadians. The Canadian Immunization Guide provides specific information on management of selected AEFI and/or special populations. AEFI expert assessment is available via several avenues. For example, all serious AEFIs are reviewed by medical specialists at PHAC and Health Canada. Where needed, experts in specific fields of study are consulted. The Canadian Immunization Research Network's Special Immunization Clinic (SIC) Network, established across Canada in 2013 by infectious disease specialists and allergists, provides expert advice to patients who have experienced adverse events following immunization and those who have medical conditions that may affect their immunizations. For more information on AEFI management, you can refer to the SIC Network's Managing Adverse Events Following Immunization: Resource for Public Health.

Global Collaboration

It is important to note that post-approval vaccine monitoring is a process that is similarly carried out in many countries around the world, and Canada's systems are linked with international networks, allowing us to share and access important safety information from other countries where the same vaccine is also in use. These networks include the Global Advisory Committee on Vaccine Safety (GACVS) which was created by the World Health Organization (WHO) and enables quick and efficient responses to vaccine safety issues of global importance.

In the case of COVID-19 vaccine monitoring, we are seeing even greater international collaboration and communication on vaccine safety. Regulatory and public health authorities in Canada are actively collaborating and regularly exchanging information with international partners such as the WHO, in order to detect and discuss any emerging safety signals as well as how any potential risks may be mitigated. Regulators are also working closely together to share information.

Instilling confidence in our vaccination program

I hope that the information that I've provided today will help to shed some more light on the vaccine monitoring process we have in place in Canada. Ensuring that all vaccines authorised for use in Canada are safe and effective is a priority for health authorities at every level, who continue to monitor, investigate and report through Canada's vaccine safety surveillance systems.

For additional information on vaccine safety, you can visit the Government of Canada's COVID-19 vaccines and treatment portal. You can also keep track of any adverse effects reported in Canada with the COVID-19 Vaccine Safety Report which is updated on a weekly basis.

With fewer infections in those over 80 years of age, along with decreased outbreaks in long-term care settings, we are seeing the real-world benefits of COVID-19 vaccinations. As these vaccines work to protect more and more Canadians, let's play our part by staying strong and helping each other - follow public health advice, keep up with individual practices, and prepare to take your place in the queue when the time comes for you to be vaccinated.


Media Relations
Public Health Agency of Canada

Page details

Date modified: