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A vial of some of the first 500,000 of the two million AstraZeneca COVID-19 vaccine doses that Canada has secured through a deal with the Serum Institute of India in partnership with Verity Pharma at a facility in Milton, Ont., on March 3, 2021.Carlos Osorio/The Canadian Press

The expert panel that advises Ottawa on which people to prioritize for vaccination is reconsidering its position that the COVID-19 vaccine made by AstraZeneca should not be given to Canadians who are 65 and over.

Meanwhile, European countries including Austria, Denmark and Italy have suspended administering the vaccine, either from specific batches or entirely, while investigating reports of blood clots in individuals who received the shot.

Caroline Quach-Thanh, who chairs the National Advisory Committee on Immunization, told The Globe and Mail on Thursday that committee members had met this week to review new data about the effectiveness of the vaccine in seniors. She said an updated statement on its use would be issued, “in a few days.”

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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.

Dropping age restrictions on the vaccine would put the committee in line with several countries that have already done so, as well as Health Canada regulators who from the start authorized the vaccine for adults 18 and over in February. Provinces are not bound by the committee’s recommendations and Quebec has already opted to make the AstraZeneca vaccine available to seniors.

Dr. Quach-Thanh noted that the advisory committee’s initial statement on the vaccine was made based on data available before March 1, which the committee deemed insufficient to provide a recommendation for those in the older age group. Since then, she said, two more British studies have appeared that provide additional data on seniors who have received the vaccine.

European officials say they are now investigating the blood-clotting incidents. Experts caution that while potential adverse reactions should be thoroughly checked, it is inevitable that unrelated health problems and death will occur after individuals have been vaccinated at a rate that is comparable to the general population.

The vaccine has already been administered to tens of millions of people worldwide.

“Any side effect that’s common should already be obvious,” said Matthew Muller, an infectious-disease physician with the Unity Health group in Toronto, who is part of a project to monitor COVID-19 vaccine safety in Canada. “We should be open-minded, but I think the appropriate thing here is to gather more information.”

The AstraZeneca vaccine has posed a conundrum for some Canadians because of its lower average efficacy. That was determined to be 62 per cent in clinical trials – a clear contrast with vaccines made by Pfizer-BioNTech and Moderna, which both scored better than 90 per cent. However, the vaccines are much closer in performance when considering their ability to prevent serious disease and death rather than all symptoms regardless of how mild.

Also important for those awaiting vaccination is the growing threat of infection posed by more transmissible variants of the coronavirus. The scarcity of doses of other authorized vaccines in Canada means that the AstraZeneca shot could play a crucial role in preventing a third wave of infections.

“Vaccines save lives,” said Cole Davidson, a spokesperson for federal Health Minister Patty Hajdu. “All of the vaccines authorized by Health Canada are safe and effective … and we encourage all Canadians to get vaccinated when their turn comes.”

On Thursday, B.C. Provincial Health Officer Bonnie Henry said she was on a call with Health Canada about the issues around the AstraZeneca vaccine, including the safety questions coming out of Europe.

“We have not seen any of those types of issues here in B.C., although we just started to use the AstraZeneca vaccine,” she told reporters at a briefing.

In Italy, national and Sicilian media have reported the deaths of two Sicilian men after they received the AstraZeneca vaccine. According to a report from Reuters, Italian health authorities ordered the withdrawal of a batch of the vaccine, designated ABV2856, after the deaths, but it was a precautionary measure and no direct link had been established. Local media reported that a 43-year-old navy officer died of a heart attack the day after his shot and a 50-year-old policeman died some 12 days after being diagnosed with deep vein thrombosis after his jab.

The European Medicines Agency (EMA), which is conducting the investigation into the product, said in a statement on Thursday, “There is currently no indication that vaccination has caused these conditions, which are not listed as side effects with this vaccine.”

The quality of a different batch used in Austria, where another death was reported, will also be inspected for possible defects.

That batch of one million doses, known as ABV5300, was used in 16 other countries in the European Union, including Spain, Sweden and the Netherlands.

In a statement issued Thursday evening, Health Canada said none of the identified batches under investigation have been shipped to Canada.

Austria intends to suspend use of the vaccine for 14 days while the investigation takes place. By Thursday, seven European countries, including Iceland, Estonia and Luxembourg, had halted the use of the ABV5300 batch. The Spanish Health Ministry said it would continue to administer doses from the batch because it was unaware of any related cases of blood clots.

In an interview, Pierre Morgon of MRGN Advisors, a Swiss-based biotech and vaccine consultancy, said: “This is a reminder that the safety database of a novel medication isn’t comprehensive until there’s a very large number of people having used the medication, representing all, or almost all, medical situations and conditions.”

Typically, vaccines and other medications are developed through clinical trials with inclusion and exclusion criteria. Any adverse effects among people with medical conditions excluded from the trials would not be known until after a product was approved and made available to the public.

AstraZeneca said patient safety was its “highest priority” and that the vaccine “has been extensively studied in Phase 3 clinical trials, and peer-reviewed data confirms the vaccine has been generally well tolerated.”

With a report from Xiao Xu

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