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Amir Imani is a clinical pharmacist and instructor at the University of Toronto. Zain Chagla is an infectious diseases physician and associate professor at McMaster University.

As more COVID-19 vaccines are approved in Canada, we gain more tools to end the pandemic.

But these vaccines won’t accomplish anything sitting in a fridge. We need to get Canadians vaccinated, and that means educating and having honest conversations with them using the best data we have. Right now, vaccines are our best hope for reducing the suffering caused by this virus.

When it comes to the choice of vaccines, the recommendation from many scientists, clinicians and epidemiologists has been the same: “The best vaccine is the first one you’re offered.” There is no political influence behind this statement. It is simply a recognition of what we know thus far and of the toll this illness has taken on our communities. The benefits of being vaccinated sooner outweigh every other metric at this stage of the pandemic. Mass vaccination is the best way forward.

While it might seem easy to compare the approved vaccines, these are imbalanced assumptions. Their clinical trials were run with different protocols, in different countries, and at different stages of the pandemic. Pfizer and Moderna did not have to deal with problematic variants in their landmark studies, and even the definition of “efficacy” varies between the trials. But it’s hard for anyone to not develop a preference after hearing about “60 to 70 per cent efficacy” with AstraZeneca and Johnson & Johnson, and “95 per cent efficacy” with Pfizer and Moderna.

Vaccines are not created equal. However, the long-term efficacy of these agents is still being borne out, and there will likely be important differences we notice over time: Some vaccines might better protect the elderly, some might confer longer immunity, and some might be more effective against variants of concern. We’re still gathering this information as it evolves over time.

Moderna, Pfizer, AstraZeneca or Johnson & Johnson: Which COVID-19 vaccine will I get in Canada?

Canada pre-purchased millions of doses of seven different vaccine types, and Health Canada has approved four so far for the various provincial and territorial rollouts. All the drugs are fully effective in preventing serious illness and death, though some may do more than others to stop any symptomatic illness at all (which is where the efficacy rates cited below come in).


  • Also known as: Comirnaty
  • Approved on: Dec. 9, 2020
  • Efficacy rate: 95 per cent with both doses in patients 16 and older, and 100 per cent in 12- to 15-year-olds
  • Traits: Must be stored at -70 C, requiring specialized ultracold freezers. It is a new type of mRNA-based vaccine that gives the body a sample of the virus’s DNA to teach immune systems how to fight it. Health Canada has authorized it for use in people as young as 12.


  • Also known as: SpikeVax
  • Approved on: Dec. 23, 2020
  • Efficacy rate: 94 per cent with both doses in patients 18 and older, and 100 per cent in 12- to 17-year-olds
  • Traits: Like Pfizer’s vaccine, this one is mRNA-based, but it can be stored at -20 C. It’s approved for use in Canada for ages 12 and up.


  • Also known as: Vaxzevria
  • Approved on: Feb. 26, 2021
  • Efficacy rate: 62 per cent two weeks after the second dose
  • Traits: This comes in two versions approved for Canadian use, the kind made in Europe and the same drug made by a different process in India (where it is called Covishield). The National Advisory Committee on Immunization’s latest guidance is that its okay for people 30 and older to get it if they can’t or don’t want to wait for an mRNA vaccine, but to guard against the risk of a rare blood-clotting disorder, all provinces have stopped giving first doses of AstraZeneca.


  • Also known as: Janssen
  • Approved on: March 5, 2021
  • Efficacy rate: 66 per cent two weeks after the single dose
  • Traits: Unlike the other vaccines, this one comes in a single injection. NACI says it should be offered to Canadians 30 and older, but Health Canada paused distribution of the drug for now as it investigates inspection concerns at a Maryland facility where the active ingredient was made.

How many vaccine doses do I get?

All vaccines except Johnson & Johnson’s require two doses, though even for double-dose drugs, research suggests the first shots may give fairly strong protection. This has led health agencies to focus on getting first shots to as many people as possible, then delaying boosters by up to four months. To see how many doses your province or territory has administered so far, check our vaccine tracker for the latest numbers.

However, there are three things we do know.

1) Thus far, all the vaccines approved in Canada for COVID-19 have shown great efficacy in preventing hospitalization and death from infection. You can still develop symptoms or test positive after receiving any vaccine, but with the caveat that the illness will be mild, and you’ll be at low risk of hospitalization, need for a ventilator, or death.

2) When it comes to vaccines, you are not “stuck” with what you get. As our supply and knowledge of COVID-19 (and its variants) grows, we can look at optimizing protection with boosters or different types of vaccines. This is a common strategy for other infectious diseases: In bacterial pneumonia, high-risk patients receive two different vaccines from two different companies sequentially in order to gain the highest level of protection. And with shingles, we’ve revaccinated individuals when a more effective product was discovered and came to market.

3) These vaccines likely lower transmission in the community. More people getting vaccinated promptly will lower our community burden and help develop herd immunity. This creates an extra blanket for us to lower all of our individual risks.

Here’s an analogy for how we see this: You’ve been sitting out in the cold without anything to shield you from the elements. Someone comes along and offers you a coat. We don’t know if it’s the warmest coat we have on the market, but it’ll protect against the cold and keep you from getting hypothermia. You could refuse and keep waiting for someone to come along with a (possibly) better one, but we’d recommend taking that first coat. We can get you bundled up better later if needed.

Voltaire noted that perfection is the enemy of the good. With multiple approved vaccines in less than a year since the pandemic was declared, we’ve entered a period of hope and optimism. The end of this suffering and a return to normal is in sight, but fixating on efficacy differences between the vaccines may hinder this. When their turn comes, we encourage all Canadians to roll up their sleeves.

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