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A doctor prepares a dose of AstraZeneca/Oxford COVID-19 vaccine before administering it to a patient in France on Feb. 26, 2021.FRED SCHEIBER/AFP/Getty Images

On Friday, Health Canada approved the Oxford University-AstraZeneca COVID-19 vaccine and a comparable one made in India, clearing the way for shots from four different companies to be used in Canada.

The regulator said the AstraZeneca shot is safe and effective at preventing COVID-19. Although less effective than the vaccines from Pfizer-BioNTech and Moderna at preventing infection, it is 100-per-cent effective in preventing the severe outcomes of COVID-19 – a key factor the federal regulator is using when considering vaccine approvals, Health Canada’s senior medical adviser Supriya Sharma said.

“This is another option, and it is a good option,” Dr. Sharma told reporters on Friday.

Canada has purchased 20 million doses directly from AstraZeneca, which are expected to be delivered between April and September.

Prime Minister Justin Trudeau announced Friday the government will also buy two million of the shots made by the Serum Institute of India – which is also making the AstraZeneca vaccine, but through a different manufacturing process. The shot from India, called Covishield, is sponsored in Canada by Verity Pharmaceuticals.

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).

PFIZER-BIONTECH

  • 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.

MODERNA

  • 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.

OXFORD-ASTRAZENECA

  • 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.

JOHNSON & JOHNSON

  • 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.

Canada will receive 500,000 shots from the institute in March, and the remaining 1.5 million doses will arrive by the end of May. The federal government will also receive 1.9 million AstraZeneca shots by the end of June through an internationally managed fund that was primarily set up for low- and middle-income countries.

It’s expected that the approval of the shots will speed up Canada’s timeline for inoculations. The federal regulator approved the latest protection against COVID-19 for individuals 18 years of age and older. Canada has also authorized the use of the Pfizer and Moderna vaccines; all are administered in two shots.

In its regulatory decision on the AstraZeneca shot, Health Canada said the vaccine has an estimated efficacy of 62 per cent. “Overall, there are no important safety concerns, and the vaccine was well tolerated by participants,” the regulator said.

The vaccine’s efficacy is well below the 94-per-cent efficacy of the Moderna shot and the 95-per-cent efficacy found with the Pfizer shots. “The key numbers that are important” are that the vaccines prevent serious illness, hospitalizations and death, Dr. Sharma said.

Health Canada said the two shots from AstraZeneca and the Serum Institute of India should be administered between four and 12 weeks after the first shot. Dr. Sharma said the data suggest the vaccine will have more efficacy with the longer interval between shots.

Some European countries have raised doubts about the vaccine’s efficacy for the elderly, but the European regulator approved it in January with no upper age limit, and now Health Canada has done so as well.

In its written authorization, the federal regulator said clinical trial data were “too limited” to give a reliable estimate of the vaccine’s efficacy for people over 65 years of age. But it said its efficacy in seniors is supported by emerging evidence where the vaccine has already been deployed.

The data “suggest at this point in time a potential benefit and no safety concerns. Efficacy in this age group will be updated as additional data become available from currently ongoing trials,” Health Canada said.

In its decision to authorize the Serum Institute vaccine, the regulators said it is comparable with AstraZeneca’s shot. Health Canada had previously said a decision on the shot from the Serum Institute would be made only after its decision on the AstraZeneca vaccine.

Zhou Xing, a viral-vaccine researcher at McMaster University in Hamilton, Ont., said he welcomed the authorization of the vaccines.

“I’m very happy about it,” he said. “As we all know, Canada hasn’t been doing that well compared to other countries in terms of vaccination coverage. We need more vaccine candidates.”

He added that despite apparent differences in efficacy, all the authorized vaccines appear to be doing a good job of preventing severe disease – an important consideration following the emergence of new, more transmissible variants of the virus. The AstraZeneca vaccine performed well in trials against the most common of the new variants to appear in Canada. That version of the virus, known as B.1.1.7, first originated in Britain and has since triggered rapid outbreaks in Ontario and Newfoundland.

One advantage that the AstraZeneca vaccine and its Serum Institute counterpart offer is ease of distribution and delivery.

Unlike the mRNA vaccines from Pfizer and Moderna, AstraZeneca’s consists of an adenovirus, which is not harmful to people but has been engineered to carry a portion of the COVID-19 coronavirus DNA. Once that DNA makes its way into human cells, it induces the cells to produce the coronavirus spike protein, which alerts immune cells to defend against anything that looks similar.

Because DNA is a more stable molecule than mRNA, the AstraZeneca vaccine does not require deep-freezing. It can be shipped and stored at normal refrigerator temperatures, from 2C to 8C, which makes the vaccine easier to administer.

The new authorizations come with new questions about how vaccines with different performance profiles and characteristics should be allocated – and to whom. Caroline Quach-Thanh, who chairs an independent committee of experts that advises the federal government on vaccine prioritization, said the committee’s recommendations related to the AstraZeneca product would be published next week.

Two additional vaccines are currently under review by Health Canada, including a one-dose adenovirus vaccine produced by Johnson & Johnson. That vaccine received unanimous endorsement from a U.S. advisory panel on Friday, which could hasten its approval by the Food and Drug Administration as early as next week.

Dr. Sharma said Health Canada’s review is in the final stages and it expects to make a decision “in line with the other major regulators.”

A vaccine developed by Novavax, which uses a manufactured protein nanoparticle and contains neither DNA nor mRNA, is also under review by Health Canada.

Prime Minister Justin Trudeau says more Canadians will get vaccinated sooner now that a third vaccine has been approved in Canada and more doses of it have been secured. Health Canada's chief medical adviser Dr. Supriya Sharma says the AstraZeneca vaccine and all the others Health Canada has approved are safe and effective against COVID-19.

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