A closer look at the vaccines Canada is betting on to stem the spread of COVID-19

Ottawa has signed deals with several groups of vaccine developers to reserve millions of doses of COVID-19 vaccines, including four that have been approved in Canada. The vaccines represent a variety of different technologies with different pros and cons. Here’s a closer look.

Ottawa has signed deals for millions of doses of vaccines from several groups of developers

Amanda Parsons, a registered nurse on staff at the Northwood Care facility, prepares a dose of the Moderna vaccine in Halifax on Monday, Jan. 11, 2021. Canada has ordered vaccines from seven different vaccine makers and plans to offer free vaccines to everyone who lives in Canada over the course of 2021. (Andrew Vaughan/The Canadian Press)

Canada has signed deals with several teams of vaccine developers to reserve millions of doses of COVID-19 vaccines, including ones from Pfizer-BioNTechModernaAstraZeneca and Janssen (Johnson & Johnson) that have now been approved in Canada under interim orders. 

Government officials say it's part of an effort to make sure Canadians are at the front of the line when it comes to vaccine distribution.

Ottawa announced agreements with Moderna and Pfizer-BioNTech on Aug. 5, 2020; with Novavax and Janssen, a subsidiary of Johnson & Johnson, on Aug. 31; with Sanofi/GSK on Sept. 22; with AstraZeneca, which is manufacturing a vaccine developed at the University of Oxford, on Sept. 25; and with Medicago on Oct. 23.

Canada will receive 20 million to 76 million doses of each vaccine that successfully makes it through clinical trials and be approved by Health Canada.

WATCH | Virologist discusses the complex landscape of COVID-19 vaccines:

Virologist discusses complicated landscape of COVID-19 vaccines

2 years ago
Duration 5:30
Montreal virologist Benoit Barbeau says Canadians should focus on getting their first shot of a COVID-19 vaccine, even as new vaccines roll out and established ones adapt to new variants.

The seven vaccines are among more than 150 candidates under development around the world.

On Dec. 9, 2020, Pfizer-BioNTech's vaccine was approved in Canada under an interim order, a week after it was approved for emergency use in the U.K. Health Canada approved Moderna's vaccine under an interim order on Dec. 23, 2020, and approved AstraZeneca's vaccine under an interim order on Feb. 26, 2021, nearly two months after approval in the U.K. and a month after approval in the European Union. Janssen's vaccine was approved in Canada under an interim order on March 5, 2021.

Novavax has released promising results from Phase 3 clinical trials, a key step to determine a vaccine's effectiveness in preventing COVID-19 and submitted applications to Health Canada for approval.

In total, the federal government has committed $1 billion to pre-purchasing vaccines and most of that money will not be refunded even if some of the vaccines never get approved.

Here's a closer look at the seven candidates.

AstraZeneca/Oxford University

Headquarters: London, U.K.

Type: Non-replicating viral vector

Doses reserved: 20 million (enough to vaccinate at least 10 million people)

Phase of development: Approved for use in Canada under an interim order on Feb. 26, 2021 

How it works: This vaccine is a new type of vaccine called a non-replicating viral vector. Unlike traditional vaccines made from viruses or parts of viruses, this vaccine uses only a coronavirus gene. The gene contains instructions for making a coronavirus protein so that the human body can produce it and learn to recognize it.

The protein targeted by most COVID-19 vaccines, including this one, is called the spike protein or S-protein. It's found on the outer surface of coronaviruses and is used by the virus to bind to and enter human cells.

In this case, DNA with instructions for making the spike protein is carried into the body by the chimpanzee version of a common cold virus called an adenovirus.

The adenovirus has been genetically modified so it can't replicate itself in the human body. However, because it's a virus, it may generate a stronger immune response than DNA alone and helps get the coronavirus gene into human cells, where the spike protein can be produced.

Viral vector vaccines mimic viral infection more closely than some other kinds of vaccines. One disadvantage of viral vectors is that if a person has immunity toward a particular vector, the vaccine is not as effective. In this case, people are unlikely to have been exposed to a chimpanzee adenovirus.

Where it's at: The vaccine was approved in Canada under an interim order on Feb. 26, 2021. It had been approved for emergency use in the U.K. on Dec. 30, 2020 and in the EU on Jan. 29, 2021. However, Canada had said it needed more data. AstraZeneca and the University of Oxford had announced promising preliminary results of their Phase 3 clinical trials on Nov. 23. Results showed the vaccine was up to 90 per cent effective at preventing COVID-19. It was more effective when the first dose was a half dose and a full dose was given a month later. That was due to a dosing error, leading to questions about the results and prompting the company to say it would run an additional global trial. Phase 3 trials of the vaccine started in August in the United States, following the start of Phase 2/3 trials in the United Kingdom, Brazil and South Africa. While the trials were paused twice due to illnesses among volunteers, the company says no serious safety events related to the vaccine have been confirmed

Janssen Pharmaceutical Companies (Johnson & Johnson)

Headquarters: Raritan, N.J., U.S.

Type: Non-replicating viral vector

Doses reserved: Up to 38 million (enough to vaccinate 38 million)

Phase of development: Approved for use in Canada under an interim order on March 5, 2021

How it works: This vaccine, made by a Johnson & Johnson subsidiary, is similar to the one from AstraZeneca and the University of Oxford except that it uses a slightly different adenovirus. Another difference is it's been tested as a single-shot. Most other vaccines require two shots to be effective.

While this is a relatively new technology, a replicating viral vector vaccine, which is similar, has been approved for protection against Ebola, and there are at least a dozen viral vector vaccines in use for diseases in livestock.

Where it's at: Health Canada approved the vaccine under an interim order on March 5, 2021. On Jan. 29, the company had announced Phase 3 clinical trials showing the single-shot was 66 per cent effective on average and 85 per cent effective against serious symptoms 28 days after vaccination. The overall effectiveness was as high as 72 per cent in the U.S., but only 57 per cent in South Africa, suggesting it is less effective against a new variant spreading there. The company ran single-shot and two-shot clinical trials simultaneously. It had reported in July that its vaccine protected monkeys against the coronavirus after a single shot. 

WATCH | Pfizer, AstraZeneca vaccines help prevent hospitalizations, Scottish data suggests:

Pfizer, AstraZeneca vaccines help prevent hospitalization, Scottish data suggests

2 years ago
Duration 2:02
New data out of Scotland indicates that two COVID-19 vaccines have great efficacy even when the time between doses is stretched out. The Oxford AstraZeneca and the Pfizer-BioNTech vaccines were found to be more than 80 per cent effective at preventing hospitalizations after just one shot.


Headquarters: Quebec City, Que.

Type: Virus-like particle (VLP)

Doses reserved: 76 million (enough to vaccinate 38 million people)

Phase of development: Phase 2/3 trial started in November

How it works: Medicago's vaccine is more traditional than the non-replicating viral vector vaccines. Like many vaccines already on the market, it's made up of a protein from a virus, the spike-protein from SARS-CoV-2.

It's slightly more sophisticated than traditional protein-based vaccines, as multiple spike proteins are assembled into a virus-like particle, or VLP. The company says that makes it look more like a virus to the immune system than disorganized protein molecules would.

The particles are made by inserting the spike protein gene into plants — tobacco relatives called Nicotiana. They're extracted by crushing the leaves.

The vaccine is being tested with an adjuvant made by GSK to boost the immune response.

Where it's at: The company started Phase 2/3 clinical trials in November after announcing promising results from Phase 1 clinical trials that started in July. As of Oct. 23, the federal government had committed $428 million to complete clinical trials and establish a large-scale vaccine and antibody production facility in Canada. Currently, its main vaccine production facility is in the U.S. 


Headquarters: Cambridge, Mass., U.S.

Type: mRNA

Doses reserved: 40 million (enough to vaccinate 20 million people)

Phase of development: In use in Canada after approval under an interim order on Dec. 23

How it works: Moderna's vaccine candidate is made from messenger RNA, a type of genetic material. Messenger RNA, or mRNA, is used by cells to translate instructions found in DNA to make proteins. In this case, the instructions tell a human cell how to make a stabilized version of the spike protein for SARS-CoV2. That introduces the protein into the body so immune cells can learn to recognize it and produce antibodies against it. 

The mRNA is encapsulated in a lipid nanoparticle (LNP) for injection into the body. The LNP "container" protects it from being degraded by enzymes and helps it enter cells, Moderna says.

The mRNA itself also generates an immune response. While mRNA vaccines have been under development and widely tested for many years, none have ever been approved for widespread human use.

Where it's at: Canada approved Moderna's vaccine under an interim order on Dec. 23, 2020, and began vaccinations in January. In total, it has purchased 40 million doses, but did not exercise the option to buy 16 million more. The company had announced on Nov. 16 that preliminary results of its Phase 3 clinical trial show the vaccine is 94.5 per cent effective. After logging enough additional infections to end the trial, it announced on Nov. 30 that it had confirmed an effectiveness of 94 per cent. The trial, which began in the U.S. in July, enrolled 30,000 adult volunteers, including "many" that are elderly or high-risk. Moderna said on Jan. 25 that its vaccine appears effective against new coronavirus variants that first appeared in the U.K. and South Africa, but is less effective against the South African variant.

WATCH | Outrage over B.C. couple jumping COVID-19 vaccine queue:

Outrage over B.C. couple jumping COVID-19 vaccine queue

2 years ago
Duration 2:05
There is growing outrage over a B.C. couple's elaborate scheme to jump the queue for a COVID-19 vaccine. They chartered flights, broke quarantines, and now face charges.


Headquarters: Gaithersburg, Md., U.S.

Vaccine type: Protein subunit

Doses reserved: 76 million (enough to vaccinate 38 million people)

Phase of development: Phase 3 clinical trials started in December in the U.K. and U.S. 

How it works: Novavax's vaccine is the most traditional of the ones reserved by the federal government. The vaccine is made from nanoparticles of a key protein from the coronavirus that causes COVID-19. When the protein particles are injected into the body with an adjuvant — a compound that enhances the body's immune response — the body learns to recognize and fight off the virus. 

"That is a tried and true way of producing vaccines and of creating immunity," Dr. Barry Pakes, a professor at the Centre for Vaccine Preventable Diseases at the University of Toronto's Dalla Lana School of Public Health, told CBC News Network.

It's similar to vaccines already on the market, such as the hepatitis B vaccine.

Novavax makes the protein by putting the genetic sequence for the protein into a virus that infects insect cells, causing them to make large quantities of protein. The protein has some small genetic modifications compared with the one found on the real virus to help it maintain a rigid shape and make it easier for the body to bind to and recognize.

Protein subunit vaccines don't elicit as strong an immune response as whole virus vaccines, so they often include an adjuvant. Novavax uses a proprietary adjuvant called Matrix-M, which is based on a type of compound found in many plants called a saponin. The company says it boosts the body's immune response and generates a bigger immune response with a lower dose.

Where it's at: Novavax began Phase 3 clinical trials in December. On Jan. 29, it said preliminary results from the U.K. on a small number of people suggested that the vaccine was 96 per cent effective against earlier strains of coronavirus and 86 per cent effective against a new variant circulating in the U.K. It is less effective against a new variant circulating in South Africa. On Jan. 31, the company submitted an application for Health Canada approval, and on Feb. 2, Prime Minister Justin Trudeau also announced that Canada had signed a deal to produce the vaccine in Canada starting later in the year.

Diane Guy receives a COVID-19 vaccine from nurse Roxanne Paradis at the Résidence l'Étoile filante, in Lebel-sur-Quévillon, Que., on Thursday Jan. 21, 2021. Vaccinations with the approved Pfizer-BioNTech and Moderna vaccines are underway across Canada. (The Canadian Press)


Headquarters: New York, N.Y., U.S./Mainz, Germany

Type: mRNA

Doses reserved: At least 20 million (enough to vaccinate 10 million people), with the government negotiating for options to reserve more

Phase of development: In use in Canada after approval under an interim order on Dec. 9

How it works: Pfizer-BioNTech's mRNA vaccine is quite similar to Moderna's. It's an mRNA sequence for a stabilized spike protein. Like Moderna's vaccine, it's delivered in a lipid nanoparticle container.

Where it's at: Vaccinations are underway after the Pfizer-BioNTech vaccine was approved in Canada under an interim order on Dec. 9. Pfizer announced on Nov. 18 that it had completed its Phase 3 clinical trial, and the updated preliminary results show the vaccine is 95 per cent effective. That's based on 170 infections in a trial of more than 43,000 participants in six countries. There were just eight infections among volunteers who received the vaccine. The results were published in a peer-reviewed journal on Dec. 10. Studies so far suggest the vaccine is effective against some mutations found in new coronavirus variants in the U.K. and South Africa, but more research is needed on other mutations.

WATCH | Other COVID-19 vaccines awaiting approval could give Canadians more choice — eventually:

Other COVID-19 vaccines awaiting approval could give Canadians more choice — eventually

2 years ago
Duration 2:06
The federal government is still evaluating other COVID-19 vaccines, including from AstraZeneca and Johnson and Johnson, which could be approved within weeks. The vaccines in the pipeline work differently and some Canadians hope that might give them a choice about which vaccine to get.


Headquarters: Paris, France/London, UK

Type: Protein subunit

Doses reserved: Up to 72 million (enough to vaccinate up to 36 million people)

Phase of development: Phase 1/2 trial started on Sept. 3, 2020, but is restarting in February 2021

How it works: This is very similar to Novavax's vaccine — it's made up of the SARS-CoV-2 spike protein with a proprietary adjuvant to boost the body's immune response. In this case, the adjuvant is made by GSK and is also being tested with a number of other vaccines, including the one being developed by Quebec City-based Medicago. Like Novavax, Sanofi is making the protein by putting the gene for it into a virus that infects insect cells. It's the same system used by Sanofi to make a flu vaccine that has government approval for widespread use. This is one of two COVID-19 vaccines Sanofi is working on. The other is an mRNA vaccine in collaboration with Translate Bio.

Where it's at: Sanofi and GSK announced the start of a Phase 1/2 clinical trial on Sept. 3 involving 440 healthy adults at 11 sites across the U.S. However, on Dec. 11, the company said the vaccine would be delayed until late 2021 due to "insufficient" immune response in people over 60. That was partly due to them receiving a lower dose than intended. The company is planning to start a new early-stage trial in February. Sanofi says some research, development and clinical manufacturing of the vaccine will take place in Toronto.


Emily Chung

Science, climate, environment reporter

Emily Chung covers science, the environment and climate for CBC News. She has previously worked as a digital journalist for CBC Ottawa and as an occasional producer at CBC's Quirks & Quarks. She has a PhD in chemistry from the University of British Columbia. In 2019, she was part of the team that won a Digital Publishing Award for best newsletter for "What on Earth." You can email story ideas to

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