Prime Minister Justin Trudeau said Canada’s vaccine rollout is still on track after the country’s top immunization experts said the AstraZeneca-Oxford vaccine should be immediately halted for adults under age 55.
Canada’s National Advisory Committee on Immunization (NACI) said Monday the AstraZeneca shot should not be used in younger adults after rare cases of serious blood clots were reported in Europe, primarily in women under age 55.
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“I understand how challenging this can be for Canadians,” Trudeau said at a press conference Tuesday. “The science is evolving; as we get more and more data, experts are refining and shifting their recommendations.”
Canada has administered 300,000 doses of the AstraZeneca vaccine with no reports of the blood clots, and had another 1.5 million doses arriving from the U.S. Tuesday.
Trudeau said the country’s vaccine portfolio is still “extremely heavily weighted” toward Pfizer and Moderna, and announced Tuesday that Pfizer-BioNTech has agreed to bump up delivery of 5 million doses of its vaccine from late summer to June.
The European Medicines Agency estimated roughly one in 1 million people vaccinated with the AstraZeneca shot could suffer from the rare blood clot—referred to as Vaccine-Induced Prothrombotic Immune Thrombocytopenia (VIPIT)—while Paul-Ehrlich Institut in Germany has pegged the rate at one per 100,000. The fatality rate is approximately 40 per cent.
Lynora Saxinger, an infectious diseases physician and co-chair of the Alberta Health Services COVID-19 Scientific Advisory Group, said messaging around the AstraZeneca vaccine has been “disastrous” and illustrates problems with risk communication.
While Saxinger said the blood clot risk is fuelling legitimate public concerns, she added the likelihood of dying from VIPIT pales in comparison to the likelihood of dying from COVID.
“The fact that it’s severe and it’s occurring in otherwise healthy people does raise the fear factor for people a lot. And a scary story can weigh a lot more than any kind of statistics that we might actually try to illustrate the relative risk with,” Saxinger said.
“It remains really a very, very small risk compared to the imminent and increasing risks of getting COVID, even at a younger age.”
Scientists have not yet identified consistent risk factors in patients. Cases have mostly occurred in men under age 55, between 4 and 16 days after receiving the vaccine. It is unclear at this point whether the reason more women have been affected is because young health care workers, one of the early priority groups for getting the shot, are predominantly female.
AstraZeneca’s vaccine uses adenovirus-vectored technology, making it easier to store and distribute than other COVID-19 shots. Moderna and Pfizer use mRNA technology that is more fragile and requires freezing, but the blood clots have not been identified following any mRNA COVID-19 vaccinations.
NACI determined that because mRNA vaccines are also available, there is “substantial uncertainty” about the benefit of providing AstraZeneca to adults under 55 and recommended halting the shots as a “precautionary measure.”
Canada’s Chief Public Health Officer Theresa Tam said experts from Canada and Germany are working with Health Canada to get more data.
“Every medication or vaccine can come with rare side effects, which will not be picked up until many millions of people receive the vaccine,” Tam said.
“Canadians should be reassured that we have systems in place to detect safety signals and analyze them. It’s actually been quite a remarkable feat of international collaboration and science to try and sort out the initial reports.”
Canada’s procurement Minister Anita Anand said Pfizer will deliver at least 1 million doses per week from now until the end of May, and at least 2 million per week every week in June, bringing Canada to 44 million total vaccine doses by the end of June. She said this means all Canadians who want a vaccine should be able to get one before summer ends. The government is also working out details with Johnson & Johnson, which will start delivering doses at the end of April.
The NACI is advising anyone who has received the AstraZeneca shot to seek “immediate medical attention” if they develop shortness of breath, chest pain, leg swelling, persistent abdominal pain, sudden onset of headaches, blurred vision, or skin bruising.
An AstraZeneca spokesperson said in an email the company respects NACI’s decision and is working closely with Health Canada to conduct a detailed assessment of the risks and benefits by age and sex.
“Tens of millions of people have now received our vaccine across the globe. The extensive body of data from two large clinical datasets and real-world evidence demonstrates its effectiveness, reaffirming the role the vaccine can play during this public health crisis,” the statement said.
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