The Complex Journey of a Vaccine

Canada’s innovative pharmaceutical industry is coming together to achieve one shared goal: the eradication of COVID-19. We are committed to and focused on creating new tests for the virus, on developing solutions to treat those already affected by it, and on finding a safe vaccine to help protect people from future outbreaks of the virus.

As the world grapples with the COVID-19 pandemic, many Canadians are looking for more information on how vaccines are developed.

Under normal circumstances, developing an innovative new medicine can take anywhere from 10 to 15 years and cost over $2-billion to develop and bring to patients. The urgency of the COVID-19 outbreak is enabling researchers, industry and government to bring together the resources which will accelerate that process to bring a potential vaccine to clinical trial status as soon as possible.

In contrast to medicines that treat disease in sick people, vaccines are designed to prevent infection and/or disease in a healthy population. Since vaccines are given to healthy people at various stages of life, from childhood to older age, it is necessary to establish a very large safety database. This requires carrying out many studies involving thousands of participants (many more than in conventional drug trials), before a vaccine can be approved and licensed.

Here are the various stages of vaccine development, from the discovery of a molecule to its availability to the Canadian public.

Discovery and Pre-clinical trials

In vaccine development, the first step is to identify potential ingredients for a vaccine candidate. Thousands or even millions of different molecules may be screened at this stage in the process, and most will be discarded.

Researchers work to narrow the number of most promising compounds, to determine the molecule(s) best equipped to influence the target disease and potentially become a medicine.

During this stage, researchers will carefully select the antigen, the substance that causes the body to create antibodies, and appropriate technologies to activate it. They will then conduct lab experiments in living cells and animals. The information collected from these studies will be vital to proceed with clinical trials in humans.

Phase I Vaccine Trials

This first attempt to assess the candidate vaccine in humans involves a small group, usually between 20 to 80 subjects. The candidate vaccine will be tested to evaluate its safety, determine a dosage range that is safe and that provides the best immune response, and identify any vaccine-related side effects. If results from the Phase 1 study are positive, the vaccine will progress to the next stage.

Phase II Vaccine Trials

The goals of Phase II trials are to study the candidate vaccine’s safety and efficacy, as well as to evaluate the proposed doses, schedule of immunizations, and method of delivery—by mouth, injection or inhalation. These trials are randomized and controlled according to well-established scientific methods.

A larger group of several hundred individuals participate in Phase II testing. This phase aims at evaluating in more detail the dose and administration schedule compared to Phase I.

Phase III Vaccine Trials

If the Phase II trial is successful, the candidate vaccines move on to further research and studies, involving anywhere from 3,000 to more than 10,000 people.

The key objective of Phase III trials is to assess vaccine safety and efficacy in a significantly large group of people and specifically those for which the vaccine is aimed.

The three phases of clinical trials usually take 4-8 years to complete, at a cost of $500-million–$1-billion (USD). However, in times of pandemic this stage must be accelerated, so that enough individuals can be found to participate in the trial who have not yet been exposed to the virus.

Approval and Licensing

After a successful Phase III trial, the vaccine researcher will submit a dossier to the appropriate national regulatory authority, such as Health Canada, for review and approval. Health Canada assesses the safety, quality, and efficacy of the vaccine. It also reviews information regarding the manufacturing facility, the method of manufacture and quality control of the vaccine.

A critical part of the process is a review that is conducted by the National Advisory Committee on Immunization (NACI) under the Public Health Agency of Canada. NACI makes recommendations for the use of new and existing vaccines in Canada, including the identification of groups at risk for vaccine-preventable diseases for whom vaccination should be targeted. NACI recommendations are published in the Canadian Immunization Guide and used by governments when considering which vaccines to fund.

Tendering for Vaccine Procurement

Once the development, regulatory, and review steps are completed, manufacturers must compete to bring their innovations to Canadians. Vaccines are procured through public tendering or bulk-buying, which helps to ensure good value for public health spending and that vaccines are affordable. Tendering processes exist jointly among federal/provincial/territorial governments and contracts are also maintained by individual jurisdictions.


Once on the market, the vaccine manufacturer will continuously assess the vaccine’s safety to detect any risk of adverse side effects associated with the vaccine. These studies are aimed at ensuring that the protection given by the vaccine is long-lasting, and to investigate new applications of the vaccine for prevention of other diseases.

Health Canada will also continue to monitor the production of the vaccine, inspect facilities and review the manufacturer’s testing processes involved in the vaccine development.

As of March 2020, is estimated that there more than 20 vaccines in development for COVID-19. It’s also important to remember that there’s no single correct route to this kind of research and discovery.

Many potential treatments will likely be explored and discarded along the way. Typically, only approximately one in ten experimental vaccines make it all the way through to regulatory approval. Therefore, the more companies taking different approaches to find a vaccine, the more “shots on goal,” which significantly increases the chance of success.

Meeting the challenge of creating a new vaccine will take close collaboration between the private sector and government agencies, along with the coordinated work of thousands of scientists, physicians, researchers and volunteers. We are committed to working with governments to find solutions to the threat of COVID-19 and we won’t rest until a vaccine and effective treatments for COVID-19 are found.

The above text is adapted from the International Federation of Pharmaceutical Manufacturers & Associations (IFPMA)’s publication: The Complex Journey of a Vaccine, published July 29, 2019. Read the full report.


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