Vaccine testing, approval, and monitoring process

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Did you know?

All vaccines go through an in-depth testing process to show that they are safe and effective before they are approved for use in Canada.

Vaccines are among the most strictly regulated medical products in Canada. All vaccines go through an in-depth testing process and must be shown to be safe and effective before they are approved for use in Canada. This process goes through several phases in order to gather all the scientific information necessary to ensure the safety and efficacy of the vaccine. 

How are vaccines tested?

Vaccine testing begins in the laboratory. If lab studies show that a vaccine has potential, it is usually tested in animals first. 

If the vaccine is shown to be safe in animals, studies in people (called clinical trials) are next. People taking part in these studies are volunteers. They understand that a vaccine is being studied and are informed about the possible side effects.

There are three phases (stages) of studies in people prior to a vaccine being approved for general use. These studies start with very few people, but the final (phase 3) studies, that are designed to show both effectiveness and safety, will have hundreds or even thousands of subjects.

If a vaccine is being developed for children, it is usually tested on adults first.

Who approves vaccines for use in Canada?

When all phases of the clinical trials have been successfully completed, the vaccine must meet Canadian licensing standards before it can be considered for approval by Health Canada.

In Canada, the Centre for Evaluation of Radiopharmaceuticals and Biotherapeutics  (BRDD) which is part of Health Canada, approves vaccines for use.

The BRDD approves a vaccine for use only if it has been thoroughly proven to be safe and effective, and only if the benefits of the vaccine greatly outweigh any risks associated with it.

The BRDD also supervises all aspects of vaccine production and quality control throughout the vaccine’s lifecycle, to ensure that the vaccine is safe and effective.

Infographic: How Vaccines Are Tested & Approved

How and why are vaccines monitored after approval?

Once a vaccine has been approved for use, and for as long as the vaccine is used, its safety is continuously monitored. Ongoing vaccine safety monitoring is essential for the detection of, and timely response to, vaccine safety concerns.

The purpose of this ongoing monitoring is to detect possible adverse events (serious or unexpected reactions) that would occur very rarely, too rarely to detect even in a large clinical trial. When millions of people receive a vaccine, rare side effects may be recognized.

By continually monitoring, we can know if there are changes in how often adverse events are occurring, or if they are occurring only in certain groups of people.

Canada has several advanced systems in place (at the local, provincial, and national levels) to carefully monitor for adverse events and to detect any vaccine safety concerns.

What is an adverse event?

An adverse event following immunization (also known as an AEFI) is a serious or unexpected reaction that happens after someone receives a vaccine. An adverse event may or may not have been caused by the vaccine.

How vaccine safety is monitored in Canada

In all provinces and territories, including B.C., health care providers are expected to report all adverse events to their local public health unit.

In B.C., a local medical health officer (MHO) or Registered Nurse (RN) then reviews these reports and makes a recommendation for future immunization. If the MHO or RN identifies any vaccine safety concerns, they communicate them to the BC Centre for Disease Control (BCCDC) and from there to the Public Health Agency of Canada (PHAC).

The reports (along with reports from other areas of the province) are then sent to the BCCDC for review.  By gathering all the reports in one place for the whole province, we can identify rare but possible safety concerns.

The reports from the BCCDC are then sent to the Public Health Agency of Canada and added to reports from all provinces and territories in a national database. These reports are reviewed regularly to identify any safety concerns. With an even larger number of reports than at the provincial level, there is even greater opportunity to identify rare but possible safety concerns.

Vaccine safety is also monitored at the international level. The World Health Organization’s International Drug Monitoring Program collects reports from over 75 countries (including Canada) and uses this global data set to monitor for any vaccine safety concerns.

Infographic: How Vaccine Safety is Monitored


Vaccine Safety and the IMPACT Surveillance System

Canada has a unique program called IMPACT (Immunization Monitoring Program ACTive) to detect adverse events related to immunization and to monitor vaccine-preventable diseases. Nurse monitors at 12 children’s hospitals across Canada (including BC Children’s Hospital) review all admissions to the hospital for certain serious illnesses. If a child with any of these illnesses had recently received a vaccine, a report is sent to the local health unit and to the Public Health Agency of Canada to be investigated further. These events are reported even if another cause may ultimately be found for the illness.

Was the adverse event caused by the vaccine?

It’s often hard to tell if an adverse event was caused by the vaccine, or by something else that happened around the same time the vaccine was given (such as an infection or onset of a chronic condition that would have occurred even if the person was not vaccinated). As a result, the details of all reports are carefully reviewed. Rates of adverse events in people who are vaccinated are compared to rates of the same events in people who are not vaccinated but are otherwise similar to them. This can help to determine if there is a true safety concern with the vaccine.

Some types of events are further investigated to clarify the cause. For instance, people who have allergic reactions may be tested to find out which component of the vaccine caused the reaction.

Mandatory reporting by vaccine manufacturers

In addition, all vaccine manufacturers must quickly report serious adverse events of which they become aware, in Canada or internationally, to Health Canada.

Vaccine Safety in Canada



Date last reviewed: 
Thursday, Feb 03, 2022