Moderna, Pfizer-BioNTech vaccines have been approved in Canada. Here's what you need to know about them

Moderna's vaccine is the second to be approved in Canada. You might have some questions. How effective are vaccines? What are the side effects? What about allergic reactions? And when can you expect to get your shot? Here are the answers.

Also: What are the side effects? When will Canada get these vaccines?

Michelle Chester, director of employee health services at Northwell Health, prepares Moderna's COVID-19 vaccine in Valley Stream, N.Y., on Dec. 21, 2020. It is the second vaccine for COVID-19 vaccine to be approved in Canada. (Eduardo Munoz/Pool photo/The Associated Press)

Two COVID-19 vaccines have been approved for use in Canada.

The first vaccine, co-developed by Pfizer and BioNTech, was approved by Health Canada on Dec. 9, and the first shots were delivered in Quebec and Ontario on Dec. 14.

Health Canada announced Moderna's vaccine was approved on Dec. 23 "after a thorough, independent review of the evidence" on safety, efficacy and quality requirements, officials said in a release.

The two vaccines are among several that have been pre-ordered by the Canadian government.

Now that getting vaccinated is on the horizon for the general public, you may have some questions about these vaccines. How effective are they? What are the side effects? How long does the protection last? What don't we know about the vaccines? And when can you expect to get your shot?

Here are some of the answers:

How effective are the Pfizer-BioNTech and Moderna vaccines?

On Nov. 18, 2020, Pfizer-BioNTech released updated results of their Phase 3 clinical trials, suggesting the vaccine is 95 per cent effective at preventing COVID-19, a little over a week after releasing interim results showing the vaccine may be 90 per cent effective.

Moderna confirmed on Nov. 30 that the updated data from its Phase 3 clinical trial shows its vaccine is more than 94 per cent effective at preventing COVID-19, following similar partial results a couple of weeks earlier.

The analyses were both conducted by an independent data monitoring board. Pfizer's updated results looked at 170 infections while Moderna's examined 196 infections to see which occurred among those who received the real shot versus those who received a dummy shot or placebo. 

With both vaccines, each participant gets two injections. 

Moderna said that of 196 COVID-19 cases so far in its huge U.S. study, 185 were trial participants who received the placebo, and 11 got the real vaccine. The only people who became severely ill — 30 participants, including one who died — had received dummy shots. Pfizer said of 170 infections, only eight occurred in the group that got the vaccine, and only one was a severe case.

Paula McMahon prepares a shot of the Pfizer-BioNTech COVID-19 vaccine in Glasgow, Scotland, Tuesday Dec. 8, 2020. Canada approved the vaccine on Dec. 9. (Jeff J Mitchell/Pool via Associated Press)

Pfizer and Moderna's Phase 3 clinical trial results were published in December in the New England Journal of Medicine. 

WATCH | Canada's top public health doctors talk about the effectiveness of COVID-19 vaccines in real world conditions:

Dr. Tam talks about the effectiveness of the COVID vaccines in real world conditions

3 years ago
Duration 2:53
Canada's chief public health officer and Dr. Howard Njoo, the deputy chief public health officer, spoke with reporters during the regular Friday pandemic briefing in Ottawa.

How effective were the vaccines for older people and those with chronic conditions?

Vaccines are often less effective in older populations, which is why there are higher-dose flu and shingles vaccines for seniors.

But both Pfizer and Moderna said the efficacy of their vaccines was consistent across age, race and ethnicity, and gender demographics. Pfizer also specified the vaccine was 94 per cent effective in adults over 65. However, neither company reported results specifically for people with chronic conditions.

WATCH | British woman, 90, first to receive Pfizer-BioNTech COVID-19 vaccine:

British woman, 90, first to receive Pfizer-BioNTech COVID-19 vaccine

2 years ago
Duration 0:48
Margaret Keenan has kicked off a global vaccination effort by receiving the first shot of the Pfizer-BioNTech COVID-19 vaccine in Coventry, England. 'Hopefully it will help other people to come along and do as I did,' she said. 

What people haven't these vaccines been tested on? 

Dr. Zain Chagla, an infectious diseases specialist at St Joseph's Healthcare in Hamilton, said the clinical trials included adults without major medical issues.

"They took people that didn't have dementia, didn't have chemotherapy," Chagla said on CBC News Network. "As you start adding those parts in the real-world setting, you may run down some of the efficacy. Now, starting at 95 per cent is pretty good."

The results also did not include trials on children.

Pfizer announced in October they were expanding testing of their vaccine trials to those 12 and older.

Moderna is also conducting studies in children from 12 years of age and older, and Health Canada said its approval could expand to include this age group if data supports it.

Authorizing vaccines for populations such as pregnant women will also take longer.

WATCH | Why the COVID-19 vaccine isn't yet ready for kids:

Why the COVID-19 vaccine is not yet ready for kids

3 years ago
Duration 1:57
In the global race for a COVID-19 vaccine, children are barely being considered, even though they account for more than 50,000 infections in Canada and research has shown kids 10 and up can spread the virus as easily as adults.

Where else have the vaccines been approved?

Pfizer-BioNTech's vaccine was approved for emergency use in the U.K. on Dec. 2 and in the U.S. on Dec. 11.

The U.S. Food and Drug Administration also issued an emergency use authorization for Moderna's vaccine on Dec. 18.

Both Pfizer and Moderna have had more than the number of COVID-19 cases required to meet the "primary endpoint" of the study, allowing them to apply for emergency approval in many countries, including Canada. 

What kind of side effects can the vaccines cause? 

Pfizer said no serious vaccine side effects have been reported, with the most common problem being fatigue after the second vaccine dose, affecting about four per cent of participants, and headache affecting two per cent.

Older adults tended to report fewer and milder side-effects after vaccination, Pfizer said. 

Moderna said most side effects in its trial were mild or moderate, but less than 10 per cent of volunteers had more severe side effects. They included pain at the injection site after the first injection and sometimes fatigue, muscle aches, joint pain, headache and pain or redness at the injection site after the second injection. The doses used in the Phase 3 clinical trial are lower than those linked to severe "systemic" side effects in three participants in an earlier clinical trial.

Moderna's vaccine has a higher dose, 100 micrograms, compared to Pfizer's, which uses 30 micrograms.

WATCH | Canada will need to build a vaccine registry as doses are delivered:

Canada will need to build vaccine registry as doses delivered

2 years ago
Duration 3:29
Experts say Canada's COVID-19 vaccine rollout needs something it doesn't currently have: a dynamic federal vaccine registry that can gather granular data about who has been vaccinated, who needs to be and how they reacted. There are only several, unlinked provincial databases in the country.

What about allergic reactions? 

When the U.K. started injecting people with the Pfizer-BioNTech vaccine, adverse reactions were reported in two people with a history of serious allergic reactions. Both were described as "recovering well."

Following the reactions, British regulators warned that people who have a history of serious allergic reactions shouldn't receive the new Pfizer-BioNTech vaccine as the regulators investigate. 

The warning applies to anyone who has had a significant allergic reaction to:

  • A vaccine.
  • Medicine.
  • Food.

It also includes anyone who has been told to carry an adrenaline shot or others who have had potentially fatal allergic reactions.

Dr. Supriya Sharma, the senior medical adviser in Health Canada's health products and food branch, said that the authorization of the Pfizer-BioNTech vaccine means that the benefits outweigh the risks. The regulator will continue to monitor for side effects as the vaccine is rolled out to Canadians.

The Canadian product monograph says if someone has had an allergic reaction to an active ingredient or a component of the vaccine then they should not take it, Sharma said. The same cautions apply to Moderna's product, Health Canada said.

If needed, the recommendation could be broadened to include people who have had severe reactions to food or other medications. 

"These are vaccines that are used in otherwise healthy people," Sharma said. "Our tolerance for safety issues is very, very low."

Adverse events related to serious allergic reactions were also reported following the rollout of the Pfizer-BioNTech vaccine in Alaska.

Allergic reactions were not reported during clinical trials. However, people with previous serious allergic reactions to a vaccine were excluded from clinical trials. And it's not unusual for rarer adverse effects not seen in clinical trials to appear once mass vaccination begins, said Dr. Samir Gupta, a respirologist and associate professor of medicine at the University of Toronto in an interview with CBC News Network.

WATCH | U.K. regulators warn of possible Pfizer vaccine allergies: 

U.K. regulators warn of possible Pfizer vaccine allergies 

2 years ago
Duration 4:45
British regulators say people who have a 'significant history' of allergic reactions shouldn't receive the new Pfizer-BioNTech coronavirus vaccine. Two adverse reactions occurred on the first day of the country's mass vaccination program. 

What about long-term effects?

Both trials started so recently that it's impossible to know if there are any. However, before approval can be sought for the vaccines, half of the volunteers must be followed for a minimum of two months, as most side effects show up within that time period. Pfizer says the volunteers will continue to be monitored "for long-term protection and safety" for two years after their second dose.

How long would people be protected by these vaccines? 

That's not known.

Dr. Supriya Sharma, the chief medical adviser at Health Canada, said after the approval of the Pfizer-BioNtech vaccine that it's an "ongoing question." However, she said it appears from the data so far that immunity among trial volunteers is lasting, and animal studies showed longer-range immunity.

BioNTech CEO Ugur Sahin has said he expected the immune response from the Pfizer-BioNTech vaccine to last for "at least one year," but he did not explain why he thought that.

WATCH | Health Canada's Dr. Supriya Sharma talks about how long immunity from the Pfizer-BioNTech vaccine lasts

Dr. Sharma is asked how long the Pfizer vaccine is effective against COVID

2 years ago
Duration 2:07
Health Canada chief medical adviser Dr. Supriya Sharma spoke with the CBC's Tom Parry during a briefing on Wednesday.

How much has Canada ordered?

Canada announced on Aug. 5 that it had preordered both the Moderna and the Pfizer-BioNTech vaccines. It later specified that it had reserved 20 million doses of each, with the option to purchase more.

Moderna said the Canadian government increased its confirmed order commitment to 40 million doses.

Each vaccine requires two doses.

WATCH | The man tasked with Canada's vaccine rollout talks about what keeps him up at night:

The man tasked with Canada's vaccine rollout talks about what keeps him up at night

3 years ago
Duration 0:42
Maj.-Gen. Dany Fortin talks about what worries him the most as he prepares Canada's COVID-19 vaccine distribution plan.

When will Canada get the vaccines?

Prime Minister Justin Trudeau said Dec. 7 that 249,000 doses of Pfizer's vaccines should arrive in Canada by the end of this year.

The rest of Pfizer's doses and all of Moderna's are slated for delivery to Canadians some time in 2021.

Besides those two, Canada has also pre-ordered vaccines from several other companies. Dr. Howard Njoo, Canada's deputy chief public health officer, said that he expects as many Canadians as possible to be vaccinated against COVID-19 by the end of next year.

WATCH | Prime Minister Justin Trudeau details Pfizer vaccine distribution plan:

Pfizer to deliver up to 249,000 doses by end of December

2 years ago
Duration 1:45
Prime Minister Justin Trudeau details initial distribution plan for first batch of Pfizer vaccines in Canada.

Which Canadians will get vaccinated first?

In Canada, the first groups recommended for vaccination are long-term care home residents and workers, followed by seniors over 80 and front-line health care workers.

Because the Pfizer-BioNTec vaccine must be stored in a freezer at temperatures between 80 C and 60 C, it will initially be sent to major hospitals in urban areas that have those types of storage facilities. It won't be sent to the territories at first because they can't store it.

WATCH | Seniors and long-term care residents at front of COVID-19 vaccine line

What kind of trials were conducted on these vaccines? 

Both companies have met their "primary endpoints" for Phase 3 clinical trials, the final human trial step before regulatory approval. While Phase 1 and Phase 2 studies are focused mainly on safety, dosing and lab indicators of an immune response, Phase 3 trials answer a key question: are those who get the vaccine protected from the disease compared to those who get a placebo? It could also reveal rarer side effects that aren't observed in smaller Phase 1 and 2 trials.

Both trials started on July 27. Pfizer's study enrolled more than 43,000 people in the United States, Argentina, Brazil, Germany, South Africa and Turkey. Moderna's study enrolled 30,000 in the U.S. In both studies, each person gets two shots, 28 days apart. Some get the real vaccine candidate, while the others get a placebo.

How were the trial participants infected or exposed with COVID-19? 

They would have been infected in the community while going about their daily activities, such as work, school and social gatherings. Because of that, most vaccine trials choose countries with a high rate of infection to accumulate enough infections — and data — more quickly.

How soon will these vaccines make a dent in the pandemic?

Dr. Bruce Aylward, WHO's senior adviser, said following the Pfizer announcement that the vaccine could "fundamentally change the direction of this crisis" by March, when the UN agency hopes to start vaccinating high-risk groups.

However, Dr. Caroline Quach, a paediatric infectious disease physician and medical microbiologist at Sainte-Justine Hospital in Montreal, cautioned we're not "out of the woods" yet, and everyone still needs to practise safety measures, such as handwashing, staying home when sick, physical distancing and wearing non-medical masks.

Experts caution that the roll out of the Pfizer/BioNTech vaccine to the general public will be slow, and logistical hurdles remain, such as the extremely cold temperature requirements for its genetic component. Moderna has said its vaccine is stable at fridge temperatures for a month and regular freezer temperatures are cold enough for long-term storage.

Chagla said even if the vaccine is safe and available, even a small number of initial doses dribbles out to the highest-risk populations in Canada, such as those over the age of 70 living in long-term care, it could help.

WATCH | U.K. vaccinates thousands against COVID-19 on 1st day

Seniors and long-term care residents at front of COVID-19 vaccine line

3 years ago
Duration 2:04
Those most at risk will be getting the first doses of COVID-19 vaccine — including health-care workers, seniors over 70 and adults in Indigenous communities. The process is expected to use all of the initial allotment and be finished by the end of March 2021.

What type of vaccine is this? What other front-runners are similar?

Both Moderna's and Pfizer's candidates are messenger RNA vaccines. Pfizer's is officially called BNT162b2 and Moderna's is known as mRNA-1273.

The vaccines consist of genetic instructions on how to make the modified spike protein from SARS-CoV-2, the coronavirus that causes COVID-19. The genes are encoded in mRNA and packaged in lipid nanoparticles. Once the vaccine is injected into the body, human cells use the instructions to make copies of the spike protein for the immune system to learn to recognize.

Pfizer's technology includes Vancouver-based Acuitas Therapeutics's lipid nanoparticles to deliver the mRNA after it's injected into our cells.

Two other mRNA vaccines — CureVac's and Arcturus Therapeutics/Duke-NUS's candidates — are in Phase 2. 

Canada also has a homegrown mRNA vaccine candidate that is currently in pre-clinical evaluation from Toronto-based Providence Therapeutics.

What are the advantages and disadvantages of this type of vaccine?

This type of vaccine does not contain any virus or viral proteins, which means it can't cause a real infection and is considered safer.

It is also relatively quick to manufacture.

Alan Bernstein, a trained virologist and a member of Canada's COVID-19 vaccine task force, called the Pfizer announcement "great results for humanity."

"There's never been a vaccine made from RNA, so this is opening up a whole new world of making vaccines if this result holds up," said Bernstein, who previously led a major HIV vaccine effort. 

However, the mRNA vaccine is a novel technology, and no vaccines of this type have been approved for widespread human use.

One disadvantage of mRNA is that it's not very stable. That means it needs to be stored at very cold temperatures. BioNTech's CEO says the vaccine needs to be kept at -70 C for longer-term storage, although the company says it can survive five days in a refrigerator.

That may make it logistically difficult to distribute, especially in less developed countries.

Moderna says its vaccine can survive a month in the fridge and can be stored for months at regular freezer temperatures of –20 C.

WHO recommends that vaccines have a shelf life of at least two weeks in the fridge and at least six to 12 months at temperatures as low as –70 C. However, in the long-term, it says vaccines should be able to be stored at –20 C.

WATCH | Pfizer vaccine 'impractical' for remote areas, Nunavut chief public health officer says:

U.K. vaccinates thousands against COVID-19 on 1st day

2 years ago
Duration 3:10
Thousands of people across the U.K. received the first doses of the Pfizer COVID-19 vaccine on Tuesday, but officials are warning there is still a long way to go before the end of the pandemic.

Can you still carry or spread the virus if you've been vaccinated?

Neither vaccine offers 100 per cent protection, which means some vaccinated people will still be able to both spread and get the disease.

As for the rest, we don't know yet.

So far, only people with symptoms have been tested in these trials, as that is the "primary endpoint" of the study — the first thing that they look for. That means it's not clear if there are asymptomatic infections.

However, Moderna says whether the vaccine prevents infection (including asymptomatic infection) is one of the "secondary endpoints" of its Phase 3 clinical trial.

Do the proposed vaccines deal with live viruses or dead ones to stimulate antibody production?

No, not these two particular ones. However, there are some other teams around the world developing COVID-19 vaccines that use live, weakened live coronaviruses, dead or inactivated coronaviruses or live viruses such as the adenovirus cold virus that act as carriers for coronavirus genes.

How effective would it be for someone who is taking immunosuppressants?

That isn't known. While both studies included people "at high risk of the severe complications of COVID-19 disease,"such as adults over 65 and younger adults with conditions such as diabetes, severe obesity and cardiac disease, they didn't specifically mention people taking immunosuppressants. However, Moderna did say that preliminary analysis suggests a "broadly consistent safety and efficacy profile across all evaluated subgroups." 

How much can Pfizer/BioNTech and Moderna manufacture?

Pfizer/BioNTech say they can produce up to 50 million vaccine doses in 2020 and up to 1.3 billion doses in 2021.

Besides Canada, they have already received preorders from other countries.

For the Pfizer vaccine, the U.S. has preordered the first 100 million doses, with option to add another 500 million. Pfizer and BioNTech say they can deliver 50 million of those doses by year end. The United Kingdom has ordered 30 million. The companies also have an agreement with the European Union for 200 million doses.

Moderna expects to have about 20 million doses, earmarked for the U.S. by the end of 2020. The U.S. has ordered a total of 100 million doses, with the option to acquire more. Moderna has also signed deals with Israel and Switzerland

Have a question? 

Send your questions about this and other COVID-19 vaccine candidates to

With files from Reuters, The Associated Press and CBC's Christine Birak

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