Despite being recently added to Canada’s COVID-19 vaccine arsenal, the AstraZeneca-Oxford shot is also adding confusion.
On Friday, Health Canada approved the vaccine for people over the age of 18. But, days later, the committee that advises the Government of Canada on vaccines seemed to contradict that.
The National Advisory Committee on Immunization (NACI) recommended Monday that the shot not be given to people over the age of 65.
The new guidelines cite “limited information” about its effectiveness in older people as the reason it’s not recommending the shot be used in seniors.
While it’s understandable to want more precise data, what we have now doesn’t mean the shot is unsafe for seniors, nor should it erode what are clear benefits, said Colin Furness, an infection control epidemiologist and assistant professor at the University of Toronto.
Furness worries the messaging has been unfortunately muddled. The takeaway, he said, should be prioritization.
“The language is unfortunate. When they (NACI) say, ‘We don’t recommend this for older people,’ it makes people frightened, like there’s a safety problem when the recommendation is not around safety at all … It’s because the evidence is thin, that’s all,” he said.
“I think a far more positive thing to say would be — We have two vaccines that already work incredibly well for older people, let’s use those for that purpose.”
Evidence and efficacy
The AstraZeneca shot is considered about 62 per cent effective at preventing severe illness from COVID-19. While it appears less effective in clinical trials than its rival injections — which sit in the high 90s — experts have long emphasized the shot still plays a vital role in protecting people and increasing population immunity.
Trial data and emerging data show there have been no hospitalizations from severe illness and no deaths among those given the shot. That’s something that shouldn’t be discounted, said Furness.
“Notwithstanding the variant from South Africa, if the vaccine converts COVID into a common cold — that’s absolutely good enough, at least for right now,” he said.
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Health Canada acknowledged some of the vaccine’s trials made analyzing tricky because of a number of factors, including a mix-up in how big the doses were during the clinical trial and questions about how effective it is against new variants of the virus, particularly one first identified in South Africa.
Dr. Samir Sinha, the head of geriatrics at Mount Sinai and University Health Network hospitals in Toronto, understands where NACI’s caution is coming from. He said the decision was based on the evidence at hand and with the intention of guiding the best public health response.
“It’s not that NACI is saying, ‘No, these shouldn’t be used in older people,’ they’re just saying, right now, we don’t have enough data to actually recommend its use in people older than 65. And that’s actually congruent with what many European countries have come up with.”
Global differences
New, emerging studies seem to complicate things further.
New data on AstraZeneca out of the U.K. — released the same day as NACI’s guidelines — shows the vaccine is “highly” effective in reducing infections and severe illness among people 70 and older in Britain.
In those over 80, the data showed that a single dose of AstraZeneca is more than 80 per cent effective as preventing hospitalization about three to four weeks after injection, according to the Public Health England study, based on real-world evidence gathered since January.
“Real-world evidence” played a considerable role in why Health Canada opted to greenlight the vaccine. Countries that have been using the AstraZeneca vaccine showed no safety concerns in seniors,” Dr. Supriya Sharma, Health Canada’s chief medical adviser, said at a briefing Friday.
Much of that data has been generated by Britain’s vaccine rollout but other places using the shot, like Scotland, have collected similar findings in older people, especially the prevention of severe disease and hospitalizations.
By contrast, France and other countries, including Germany, Italy and Austria have opted to not recommend the shot to the elderly, also citing a lack of sufficient data.
However, France departed from that stance on Tuesday. It will now allow people under 75 with existing health problems to get the AstraZeneca shot. Those older than that will continue to get Pfizer and Moderna only.
“We’re going to see different health authorities come to slightly different conclusions,” Furness said.
“It has to do with local culture and conditions, tolerance for risk, vaccine supplies … It’s a pretty complicated thing to try and figure out the best way to deploy vaccines for maximum benefit in the population.”
Canada’s top doctor, Theresa Tam, suggested the same sort of changes could happen with NACI guidelines.
“As they see more and more of that real-world data accumulating, that will be adjusted as well,” she said Tuesday.
“This is both a challenge but also really exciting because I think the real-world data helping us adjust our vaccine program is a really positive move, but don’t read the recommendations as static, they will update as needed.”
So, who should get it?
Ultimately, the final call rests in the hands of provinces and territories, and each region could make a different decision.
Ontario, for example, has decided it won’t administer the AstraZeneca vaccine to seniors but will continue with Moderna and Pfizer’s.
Some experts suggest that essential workers who are more likely to contract and transmit the virus should be prioritized for AstraZeneca’s vaccine now that NACI isn’t currently recommending it for seniors.
The World Health Organization has suggested it be used for health workers and continues to recommend those 65 and older get it too.
It will come down to maximizing the vaccines we have with “strategic implementation,” said Dr. Raywat Deonandan, an epidemiologist and science communicator based at the University of Ottawa.
“We get the biggest bang for our buck if we use the AstraZeneca dose on people less likely to be hospitalized and die,” he said.
“This way we can work to getting herd effects, if not actual herd immunity, a bit faster.”
That kind of strategy could also include migrant farmworkers, the homeless population and other people we “don’t call first responders, and we don’t call old” who should be prioritized, Furness continued.
Coordinating that kind of strategy will not be easy, he said.
British Columbia’s provincial health officer, Dr. Bonnie Henry, is of the same thinking.
She said essential workers including first responders, teachers and those who work in meat production plants — where outbreaks have been acute in Canada — could be offered the AstraZeneca shot sooner.
“It’s really a changing landscape,” Furness continued.
“It’s all fine and good to come up with these plans, but then another vaccine gets approved and we’ve got to kind of throw them out and start again. It’s a nice problem to have.”
— With files from the Canadian Press, Reuters and Global News’ Saba Aziz
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