CPHO Sunday Edition: Canada’s Two New COVID-19 Vaccines: What You Should Know


The CPHO Sunday Edition

March 7, 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.

Next Thursday, March 11th marks the one year anniversary of the pandemic, as declared by the World Health Organization. It is hard to believe it’s been a full 12 months, and it is important to acknowledge all the hardships and sacrifices that have been made along the way, including, tragically, all those we have lost. COVID-19 has affected us all deeply, as individuals, as communities, and as a country.

Yet, as the months have gone by, I have also witnessed the remarkable courage, strength, and generosity demonstrated by Canadians. Through it all, it is the incredible support that Canadians have shown for one another that has impressed me the most.  This has included, most recently, touching accounts of family and community members, kindly stepping up to help those around them who are eligible to receive a COVID-19 vaccine, by helping them to schedule their vaccination appointments and getting them to where they need to go to be vaccinated.

And as COVID-19 vaccines continue to roll out across the country, it is has been extremely encouraging to witness the recent approval of additional COVID-19 vaccines! A little over a week ago, Health Canada authorized the AstraZeneca COVID-19 vaccine, developed in partnership with Oxford University, and the Serum Institute of India’s version of the Astra Zeneca vaccine, for use in Canada. This past Friday, more good news arrived with the approval of the single dose COVID-19 vaccine manufactured by Janssen Inc. These new vaccines provide us with additional options to help get more people vaccinated sooner while also mitigating the risk of supply disruptions and potential vaccine candidate setbacks or failures.

Many Canadians are curious and have questions about these newly available vaccines. This is completely normal and a good thing! We all want to be well-informed when it comes to issues that relate to our health – myself included. And so, to help you better understand what these encouraging developments mean for you and your loved ones, this Sunday Edition will be the first in a two-part series which dives a little deeper into Canada’s approved COVID-19 vaccines. Today, I will focus on the AstraZeneca and Janssen vaccines, and answer some key questions that have been circulating over the past week or so.

How do these new vaccines work?

You have likely heard that the AstraZeneca and Janssen vaccines are both referred to as viral vector-based vaccines. But what exactly does this mean?

Simply put, this type of vaccine uses a modified virus – the vector – as a special delivery system to carry the genetic instructions for making the SARS-CoV-2 spike protein (the protein studded on the surface of SARS-CoV-2). For the AstraZeneca and Janssen vaccines, the vectors used is are modified adenoviruses. The adenovirus is a common virus that can cause cold-like symptoms. It is safe to use as it has been adapted so that it cannot replicate and does not cause an infection.

Once the viral vector-based vaccine is injected into our bodies, the vector enters our cells and instructs them to make copies of the spike protein. The cells then present the spike proteins, or fragments of the protein, on their surface. This enables us to develop a specific immune response against the spike protein, including the priming of immune cells and the production of antibodies, which will help our bodies to recognize the virus and target it for destruction should we be exposed to it at a later time.

In terms of administering these two vaccines, the AstraZeneca vaccine currently requires two doses, while the Janssen vaccine is currently the only single dose COVID-19 vaccine that has been approved to date.

Are the new vaccines safe?

As with all COVID-19 vaccines, Health Canada authorized the AstraZeneca and Janssen vaccines after an independent and thorough scientific review for safety, efficacy and quality. After assessing all the data, Health Canada concluded that there was strong evidence that showed that the benefits of these vaccines outweighed the potential risks. For more information on Health Canada’s review of these vaccines, I would encourage you to visit the Government of Canada’s COVID-19 vaccines and treatments portal.

No major safety concerns were identified in Health Canada’s review of the clinical trial data for the AstraZeneca or Janssen COVID-19 vaccines. For both of these vaccines, the side effects observed during the clinical trials were generally similar to those experienced with other vaccines and were mild to moderate, resolving within a few days. These included: tenderness and pain at the injection site, headache, fatigue, and muscle pain. As with all vaccines, the chance of a serious side effect, such as an allergic reaction, is rare.

The manufacturers of both of these vaccines plan to follow clinical trial participants for two years after the vaccine is given and they are required to communicate any safety concerns to Health Canada. Health Canada and the Public Health Agency of Canada, in collaboration with the provinces and territories, international partners, and the manufacturer, are also actively monitoring the safety of these vaccines very closely. As with all vaccines, Health Canada will take appropriate action, as necessary, to protect the health and safety of Canadians.

How well do they work?

There has been lots of discussion over the past week about the efficacy of the different approved vaccines and what this means for Canadians seeking to be vaccinated.

It is important to note that it is not possible to directly compare the efficacy of different vaccines to one another at this time, as they were not directly compared within the clinical trials themselves. Each vaccine was studied in a separate trial conducted at different times, using different populations and conditions.

In addition, given that the AstraZeneca and Janssen vaccines were studied in separate trials with different populations, the representation of various age groups is different which limits what we are able to conclude in terms of comparative efficacy. With all this in mind, here is a brief breakdown on efficacy data from the clinical trials with respect to age:

Adults 18 to 64 Years of Age: Clinical trials for both vaccines were limited to those aged 18 years or older.

  • The Janssen vaccine was shown to be 66% effective overall in preventing moderate to severe COVID-19.
  • The AstraZeneca vaccine was found to have an efficacy of 62% in generally preventing symptomatic COVID-19. The efficacy appears to be greater if there is a longer time period between the first and second doses.
  • Both of these vaccines were found to confer significant protection against severe disease, hospitalization, and death – suggesting that even if you do get sick with COVID-19, you are likely not to become as severely ill. 

65 Years and Above:

  • The Janssen vaccine demonstrated consistent protection across all race and age groups, including adults 65 years of age or older. Almost 20% of the participants in the clinical trials were 65 years of age or older, and no differences in safety or efficacy were seen compared to the younger age groups.
  • For the AstraZeneca vaccine, there was an insufficient number of clinical trial participants aged 65 years and older who contracted COVID-19 to confirm the extent of efficacy of this vaccine for this age group.  These findings are discussed further below. However, real world data from other countries increasingly shows that the vaccine may be effective in older age groups with no safety concerns.

What roles do Health Canada and NACI play in vaccine approval?

With new COVID-19 vaccines coming to market in Canada, we are all in the process of familiarizing ourselves with how they work, are regulated, and recommended for use in Canada. To do so, it is very helpful to understand the role of the different authorities involved in making these decisions and how their work impacts vaccine allocation. 

For example, this week there has been a lot of information circulating about the regulations and recommendations for the AstraZeneca vaccine. Health Canada has authorized its use in adults aged 18 years or older, while in their recently updated guidance, the National Advisory Committee on Immunization (NACI) did not recommend that the AstraZeneca vaccine be given to those aged 65 or over due to limited data on the efficacy of the vaccine in this subgroup in the clinical trials. This has understandably led to questions about how Health Canada and NACI arrive at their decisions and recommendations regarding vaccines. While at first glance, it may appear that the NACI recommendation conflicts with Health Canada’s decision, it is a good example of how the roles of Health Canada and NACI complement each other. 

Health Canada, as a regulatory authority, reviews each vaccine submission independently to assess if there is sufficient evidence of safety, efficacy and manufacturing quality to meet regulatory requirements for authorization.

Health Canada’s approval of the AstraZeneca vaccine in adults aged 18 years or older is based on the evaluation of the data from the AstraZeneca clinical trials which demonstrated that this vaccine is safe to use in this age group and that the benefits of use of this vaccine generally outweigh the risks. However, Health Canada acknowledges that there is an insufficient number of participants in the Phase 3 clinical trials who are over 65 years of age and contracted COVID-19 to determine efficacy in this subgroup.

NACI is an external group of experts that provides federal, provincial, and territorial jurisdictions with independent advice on the use of vaccines to inform immunization programs. In their recently updated guidance, NACI provided recommendations against using the AstraZeneca vaccine in those 65 years or older at this time. NACI can and has historically provided advice that promotes or restricts the use of some vaccines compared to others. One key reason for this is that NACI takes into consideration the broader, real-world context. In this case, in addition to the limited data on efficacy in this age group, NACI also accounted for the availability of other COVID-19 vaccines at the time, specifically the Pfizer-BioNTech and the Moderna vaccines, which have been demonstrated to be highly efficacious in this population.

It is also really important to understand that these recommendations are not fixed; they are based on the evidence that is available at the time. Therefore, they will continue to be updated as more data becomes available and as additional COVID-19 vaccines are approved in Canada. Further information from ongoing clinical trials and post-market monitoring is expected in the coming weeks and months.

NACI is currently reviewing the evidence for the Janssen vaccine and will be providing advice in the coming weeks.

It is also important to note that federal, provincial, and territorial governments make their own decisions on the use of the vaccines within their jurisdictions based on a number of other factors such as:

  • Local COVID-19 epidemic conditions; including risk of exposure, severe illness or death;
  • Local vaccine supply; and
  • Logistical considerations.

Supporting the priority vaccination programs

The authorization of two new vaccines provides additional tools to fight this pandemic as quickly as possible. Having additional vaccines from different manufacturers can help to meet volume requirements to get more people vaccinated sooner and also offers more vaccination options. Different types of vaccines also provide certain advantages. As viral vector-based vaccines, the AstraZeneca and Janssen vaccines are more easily transported and stored as they may be refrigerated rather than requiring freezer storage like the Pfizer-BioNTech and Moderna vaccines.

This week has been a very good week for Canada’s COVID-19 vaccination programs. I would like to encourage all Canadians to keep up the great work in supporting these efforts by staying informed, asking questions, seeking credible information on vaccines and checking in regularly with local and provincial/territorial public health authorities to see when you or your family members may be eligible for vaccination. Continue to reach out to others who may need assistance in accessing these programs.  

All of these steps will help us to protect as many Canadians as possible, as quickly as possible. These actions, in combination with remaining vigilant in our public health measures and individual practices will help ensure we can preserve the progress we have made over the past year while shaping our future for the better in the months ahead.


Media Relations
Public Health Agency of Canada

Page details

Date modified: