No evidence to suggest AstraZeneca's COVID-19 vaccine causing adverse events: Tam
CBC News | Posted: March 16, 2021 1:19 PM | Last Updated: March 16, 2021
National Advisory Committee on Immunization updated its recommendations this morning
Canada's chief public health officer said today there is no evidence to suggest the AstraZeneca-Oxford COVID-19 vaccine is causing adverse events — and the vaccine's benefits outweigh any risks.
Dr. Theresa Tam told reporters at a media briefing that federal, provincial and territorial authorities are "continuously monitoring" vaccine safety after nearly a dozen European countries suspended the vaccine's use in response to concerns about blood clots.
"Health Canada is aware of reports of serious adverse events in Europe following immunization with the AstraZeneca vaccine, but wants to reassure Canadians that the benefits of the vaccine continue to outweigh its risks," she said.
"There is currently no indication that the vaccine caused the observed event."
To date, she added, "no unexpected vaccine safety issues have been identified in Canada."
Speaking in French, Deputy Chief Public Health Officer Dr. Howard Njoo said the data show the rate of adverse events among those who have received the AstraZeneca product is not markedly different than the rate for the general population. He also pointed out that the AstraZeneca doses deployed in Canada were made in India and come from a different batch than those sent to Europe.
Njoo said he would take any vaccine that was offered to him.
The Canadian doctors' sentiments were echoed today by Europe's medicines watchdog, which also cited the benefits of the vaccine. The European Medicines Agency said it was carrying out a case-by-case evaluation of the reported blood clot incidents and is expected to complete a review by Thursday.
NACI expands age recommendations for AstraZeneca
The National Advisory Committee on Immunization (NACI) today changed its guidelines on the AstraZeneca-Oxford COVID-19 vaccine and is now recommending it be given to those over the age of 65.
Earlier this month, the committee, which makes recommendations on the use of newly approved vaccines in Canada, recommended that Canadians over 65 not receive an AstraZeneca-Oxford shot, while Health Canada, the regulator, had authorized its use in adults of all ages.
NACI's initial recommendations were based largely on AstraZeneca-Oxford's clinical trial data and didn't examine real-world evidence past Dec. 7 — months before the effectiveness of the vaccine was fully realized in other countries for older age groups.
Dr. Caroline Quach-Thanh, chair of the committee, said the team updated its guidance based on recent real-world effectiveness studies — including new evidence from the United Kingdom, which has been administering the AstraZeneca vaccine to people 65 years of age and older.
"I think that people have to realize that if we're flip-flopping, it's just that we try to monitor the evidence," she told a news conference.
Dr. Noni MacDonald, a professor of pediatrics at Dalhousie University and a global expert on vaccine hesitancy, said Canadians need to understand that science changes.
"The major point we need to keep making is advice will be adjusted as science evolves. This is what happened here — more evidence from real-world studies showed Oxford-AstraZeneca to be very effective in those over 65 years in decreasing hospitalization and deaths due to COVID-19," she said.
"We recognize changing advice can cause anxiety but [it needs] to change as science evolves — that is a good thing."
Quach-Thanh said the reasons behind the discrepancy between NACI and Health Canada could have been communicated better.
"I think the only thing that I would say would have been done differently is the communications support, so that we would have been able to explain all this exactly as we're doing today," she said.
"I think the Public Health Agency of Canada has now recognized that this support was absolutely necessary and this is now put in place, could have been done earlier. But, you know, it's the first pandemic of this size."
mRNA vaccines should still be 'prioritized:' NACI
While NACI has expanded the age group for the AstraZeneca-Oxford dose, which is a viral vector vaccine, it is also recommending that mRNA vaccines, like those from Pfizer-BioNTech and Moderna, be prioritized for at-risk groups.
"While all available vaccines in Canada are safe and effective, NACI still recommends that in the context of limited vaccine supply, initial doses of mRNA vaccines should be prioritized for those at highest risk of severe illness and death and highest risk of exposure to COVID-19," said a statement from the committee.
Dr. Isaac Bogoch, an infectious diseases physician and member of Ontario's COVID-19 vaccine task force, said he's worried that recommendation could also cause confusion and hesitancy.
"The recommendation basically suggests that people over the age of 65 should preferentially get an mRNA vaccine over this vaccine and I think it's premature to compare vaccines head-to-head at this point in time for a variety of reasons," he said.
"When we also put this in the context of Canada being in the midst of a public health emergency where we know all available vaccines will significantly reduce the risk of getting the infection ... we wouldn't certainly want anyone to delay getting a potentially lifesaving vaccine while waiting for another vaccine, and there's some concern that that could happen. And in fact, we're already hearing about stories of people delaying getting vaccine A for vaccine B."
The provincial governments will now have to decide how to weave the new recommendations on AstraZeneca into their vaccine rollouts.
Tam said there is some early evidence to suggest vaccines are preventing deaths already. She said her department is monitoring the rate of COVID-19-related deaths to see if it's decreasing due to the vaccines or public health measures.
"Some of the most high risk groups are being vaccinated as a priority. The good news is, based on reporting from the provinces, the rates in the over-80 year olds has come down below the rate for the other age groups now. That suggests the vaccines might have a good effect," she said.
"That kind of drop is really encouraging."
Watch: Dominic LeBlanc on when Canada will get more vaccine doses from India's Serum Institute:
Canada has received 500,000 doses of the AstraZeneca-Oxford vaccine from India's Serum Institute so far, with 1.5 million more doses still expected.
Intergovernmental Affairs Minister Dominic LeBlanc told CBC News Network's Power & Politics his government has daily conversations with global vaccine producers — but he still doesn't have a confirmed date for the arrival of the remaining two million AstraZeneca-Oxford doses from India.
"Everything we've been told is that we should expect more doses of AstraZeneca in the coming weeks and as soon as that information is firmed up ... we share it with the provinces," LeBlanc told host Vassy Kapelos.