Understanding the COVID-19 Vaccine development process

Understanding the COVID-19 Vaccine development process

From the beginning of the pandemic, the world had waited patiently for a COVID-19 vaccine. While the announcement of vaccines for COVID-19 was welcomed with great enthusiasm, discussions have continued about their safety and effectiveness, as it took less than a year to develop these vaccines. It may all seem a bit rushed, but this quick response to coronavirus disease (COVID-19) is not an exception. Over the decades, scientists and researchers have been asked to respond urgently to global public health crises including Ebola, Zika, and H1N1 influenza. So, how are vaccines developed in Canada? And was the development of the COVID-19 vaccines rushed? Here’s what you need to know.


How vaccines are developed

Vaccines are probably the most effective way to end the pandemic, but developing a vaccine can be very challenging. In general, all vaccines go through 3 stages of development: the exploratory stage, the preclinical stage, and the clinical stage.1


In the exploratory stage, scientists do laboratory research to find vaccines that might help us develop immunity to a disease before being exposed to it.


In the preclinical stage, scientists conduct lab and animal studies to determine if the vaccine will create an immune response, and to address safety issues before testing on humans.1 This stage also helps find the best dose with the fewest side effects for the next stage. Many potential vaccines don’t progress beyond this point, but the successful ones move on to the clinical stage where they will be tested on humans.


There are 3 main phases of the clinical stage: phase 1, phase 2, and phase 3.1 In phase 1, the vaccine is given to a small number of healthy individuals to test its safety. In phase 2, the vaccine is given to more people who fit the characteristics of the intended target population.1 This phase is used to assess the efficacy as well as any side effects. During phase 3, the vaccine is given to a larger, more diverse group to establish the efficacy and monitor for side effects. This phase is important to ensure that the benefits of the vaccine outweigh the risks. 


Once the vaccine has gone through these 3 stages, the manufacturer submits an application to Health Canada.2 Health Canada experts then conduct a thorough and independent review of all the vaccine data received. Once they agree that the vaccine is safe and effective, its benefits outweigh the risks, and it meets manufacturing quality, they approve the vaccine.2,3


What was different this time?

Both the Moderna (Spikevax®) and Pfizer-BioNTech (Comirnaty®) COVID-19 vaccines use mRNA technology. While this is a new method for developing vaccines, the technology itself has been around for decades, and has been used to study infections such as the flu, Zika, rabies and cytomegalovirus (CMV). mRNA vaccines can be developed in a lab using readily available materials, so they are easier and faster to produce. If you’re interested in reading more about the mRNA vaccines, click here.

The AstraZeneca (Vaxzevria®) and Janssen (Johnson & Johnson) COVID-19 vaccines use viral vector-based technology. Much like the mRNA vaccines, viral vector vaccines have been used for over 4 decades in areas such as gene therapy and Ebola vaccines. Viral vector vaccines are able to provide long-term protection and may have less extreme storage and handling requirements compared to other vaccine types.4

During the development of the COVID-19 vaccine, scientists have worked to accelerate the process by merging participants in phase 2 of the clinical stage with participants in phase 3.1 This approach has allowed scientists to shorten the overall timeline and number of participants needed.1 Advances in science and technology over the years, as well as international collaboration in the fight against COVID-19 also helped speed up this process.


Health Canada also used a fast-tracked process that allows manufacturers to submit data as it becomes available, allowing them to start reviewing it right away.2


It was indeed the fastest vaccine development process we’ve ever seen in history, but this does not mean that safety has been compromised in any way. The Moderna (Spikevax®), Pfizer-BioNTech (Comirnaty®), AstraZeneca (Vaxzevria®) and Janssen (Johnson & Johnson) COVID-19 vaccines were approved by Health Canada because they showed reliable evidence and met all the requirements.3 With immense investment, expertise and collaboration on a global scale, everything was made possible in a short period of time.


Find your nearest Shoppers Drug Mart location here, and speak to one of our pharmacists if you’re interested in receiving a COVID-19 vaccine.



  1. Government of Canada. COVID-19: How vaccines developed. Available at: https://www.canada.ca/en/public-health/services/video/covid-19-how-vaccines-developed.html. Last updated July 14, 2021. Accessed October 12, 2021.
  2. Government of Canada. Vaccines and treatments for COVID-19: Progress. Available at: https://www.canada.ca/en/public-health/services/diseases/2019-novel-coronavirus-infection/prevention-risks/covid-19-vaccine-treatment.html. Last updated June 21, 2021. Accessed October 12, 2021.
  3. Government of Ontario. COVID-19 vaccine safety. Available at: https://covid-19.ontario.ca/covid-19-vaccine-safety. Accessed October 12, 2021.
  4. Government of Canada. COVID-19 mRNA vaccines. Available at: https://www.canada.ca/en/health-canada/services/drugs-health-products/covid19-industry/drugs-vaccines-treatments/vaccines/type-mrna.html#a1. Last updated September 2021. Accessed October 12, 2021.