Update: On Feb. 26, Health Canada approved the AstraZeneca/Oxford vaccine.
A few hours after the European Union authorized the AstraZeneca/Oxford University COVID-19 vaccine on Friday, Jan. 29, Health Canada issued a press release, saying that it was “currently completing its review of the submitted [AstraZeneca] data and expects to make a decision on the authorization of the AstraZeneca vaccine in the coming days.”
Canada is part of a collaborative process with the European Medicines Agency that allows regulatory authorities to “share information throughout the scientific review.” The regulators are using “rolling reviews,” meaning they begin evaluating data as it becomes available from the manufacturer, instead of waiting to receive a complete dossier before starting their work.
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AstraZeneca formally submitted its COVID-19 vaccine to Health Canada for approval on Oct. 1. The vaccine has already been approved for use in the EU, Britain, Mexico and a dozen other nations, but other approvals, including in Canada and the United States, are taking longer.
In part, that’s because some of the vaccine’s trials (in Britain, Brazil, South Africa and the United States) are still continuing, including a 30,000-person phase-three trial in the U.S. that is expected to end in March. As well, some volunteers in an early trial were inadvertently given only half of their first doses, which complicated analysis of the data.
Here’s a breakdown of what we know about the vaccine:
How many doses of the AstraZeneca vaccine do you need?
Two doses, a minimum of 28 days apart (though it can be up to 12 weeks in Europe.) Also, new analysis, in the efficacy section, supports a longer period between doses.
What is its efficacy?
There are a lot of numbers being bandied around. Here are the top ones:
- On Feb. 1, a preprint analysis in The Lancet, which looked at updated data from trials in Britain, Brazil and South Africa, found that there was 76 per cent efficacy as of day 22 post-vaccination and that level of protection lasted until a second dose at day 90, after which efficacy rose to 82.4 per cent.
- Interim results reported in The Lancet in December showed efficacy was 62.1 per cent for doses 28 days apart, with a pooled average from Britain and Brazil of 70 per cent.
- For volunteers who received low initial doses followed by full second doses, efficacy was 90 per cent, though experts aren’t sure why, StatNews reported in December (it may be a chance result).
Have there been any severe outcomes?
This result shouldn’t be underestimated, experts say. “I don’t actually care about infections. I care about hospitalizations and deaths and long-term complications,” Dr. Ashish Jha, the dean of the Brown University school of public health, told the New York Times. In addition, the Times noted that, “of the roughly 75,000 people who have received one of the five [vaccines from Pfizer, Moderna, AstraZeneca, Novavax and Johnson & Johnson] in a research trial, not a single person has died from COVID, and only a few people appear to have been hospitalized. None have remained hospitalized 28 days after receiving a shot.”
Does the AstraZeneca vaccine prevent transmission of COVID-19?
This has been an unanswered concern for all of the vaccines, and a reason why those vaccinated still wear masks so as to protect others.
Initial results look promising, as the authors of The Lancet’s Feb.1 analysis of the AstraZeneca/Oxford vaccine report a 67 per cent reduction in transmission of the virus after the first dose of the vaccine, “based on swabs obtained from volunteers in the U.K. arms of the trial.”
What are the advantages of this vaccine?
It’s a cheap vaccine that is relatively easy to make, and has standard refrigeration storage requirements, unlike the ultra-cold freezers needed to store Pfizer and Moderna versions.
(The World Health Organization has ordered 170 million doses of the AstraZeneca/Oxford vaccine, along with another 200-900 million doses of either the AstraZeneca or Novavax vaccines, which will be supplied by the Serum Institute of India.)
Are there any “known unknowns”?
As of now, there isn’t much data on how well it works with seniors. The European Union has authorized it for use for all adults; France and Germany say it shouldn’t be given to their residents who are 65 years and older. As well, it’s still unclear how well it protects against new variants.
How many doses of AstraZeneca has Canada ordered?
Are there any concerns with this vaccine?
Well, yes, there are a few. For one, trials are still being conducted, so the pooled efficacy rate will likely change. Also, there’s the outstanding question of how well the vaccine will hold up against new variants such as B.1.1.7 and experts want to see more data on its efficacy for seniors.
And then there is AstraZeneca’s fight with the European Union. The EU was furious when, in late January, AstraZeneca suddenly announced it was cutting its delivery of doses to the EU by 60 per cent in the first quarter of the year. AstraZeneca has been struggling with manufacturing and supply problems; in particular, it has apparently been getting different yields and productivity from its plants, which resulted in lower vaccine production, the company’s president admitted.
The European Union reacted by threatening to impose export controls for the vaccine. A pressing concern for Canada is that Europe’s actions may impact our vaccine deliveries, including from Pfizer. If Canada’s doses of the AstraZeneca vaccine come from Europe, then there will be concerns as to whether the EU will allow those shipments.
On Jan. 27, Prime Minister Justin Trudeau talked about the issue with European Commission President Ursula von der Leyen, who “provided assurances that the proposed European Union vaccine export transparency mechanism is not intended to disrupt exports of vaccines to Canada,” according to the official readout of the call.
As Canada rolls out the country’s most complex vaccination project to date, Maclean’s presents Vaxx Populi, an ongoing series in which Patricia Treble tackles the most pressing questions related to the new COVID-19 vaccines. Send us a question you’d like answered at firstname.lastname@example.org. If you have specific questions about your own health, we recommend consulting a family doctor or the local public health authority in your area.