According to the NACI website, this is “due to limited information on the efficacy of this vaccine in this age group at this time.”
However, the agency said the vaccine has “demonstrated an average efficacy of approximately 62 per cent in those aged 18-64 years of age.”
The vaccine received approval from Health Canada on Friday.
The NACI advice follows similar plans in many European countries. The European Medicines Agency said the vaccine could be used on all adults, but a number of countries decided not to use it for seniors because of the limited clinical data.
However, on Monday, French Health Minister Olivier Veran reversed course, saying the vaccine has been found to be very effective against the virus.
Further, Public Health England released data from a pre-print of a real-world study on Monday which said the AstraZeneca vaccine has been found to be “highly effective” in reducing infections among people 70 and older.
However, that study has not yet been peer reviewed.
The new guidance from the NACI also said the AstraZeneca vaccine should be delivered in two doses four to 12 weeks apart.
However, the committee said the interval between the first and second dose of the vaccine may impact the shot’s efficacy, “with lower efficacy if the interval is less than 12 weeks.”
The AstraZeneca vaccine is the third to have receive regulatory approval in Canada, joining ones from Moderna and Pfizer-BioNTech.
Canada has ordered 24 million doses of the vaccine.
A senior government official told The Canadian Press on background that the first of the AstraZeneca vaccines could arrive in the country as early as Wednesday, though the shipment has not been confirmed.
In an emailed statement, Verity Pharmaceuticals told Global News 500,000 doses of the vaccine will arrive in Canada from India mid-week.
“A further 1 million doses will arrive in mid-April and 500,000 in early May,” the statement read.
Speaking to reporters on Friday, Dr. Supriya Sharma, Health Canada’s chief medical adviser said while the vaccine was not tested on people over the age of 65, “emerging, promising” real-world data from countries already using the product suggest it is safe and effective among older age groups.
“For someone 65 years and older, the question is, the benefits of getting the vaccine versus not, will it outweigh the risk? The answer to that is yes, based on all the information we have,” she said.
In an interview with The Canadian Press on Monday, Sharma said Health Canada noted the concerns about the vaccine’s clinical data, but authorized it because the data showed it was safe and effective in all adults.
“I agree with the recommendation,” she told the Canadian Press.
While the NACI releases recommendations, the provinces and territories have the final say on how the vaccines are administered within their jurisdiction.
However, at least one province has decided it will follow the advice from the NACI.
On Monday, Alberta’s Health Minister Tyler Shandro said the province would not administer the AstraZeneca vaccine to anyone over the age of 65.
He said how that will change the administration of vaccines to those who are in Phase 2 is “still to be determined.”
“We’ll be making those decisions and announcing them fairly soon,” he said.
While the AstraZeneca vaccine has a lower reported efficacy rate than the Pfizer and Moderna vaccine, Dr. Isaac Bogoch, an infectious diseases faculty member at the University of Toronto, told Global News that Canadians should not be concerned about it, adding that it’s “not really a fair comparison.”
He said when the Pfizer and Moderna vaccines were tested the new, more transmissible variants of the coronavirus were not yet circulating.
“And then of course, when the AstraZeneca vaccine was tested it was tested in an era of variants of concern,” he said. “So that 94 per cent efficacy and that 62 per cent efficacy those aren’t entirely fair – there’s more of a level playing field than the numbers would suggest.”
Bogoch said all of the approved COVID-19 vaccines are “very, very effective in preventing significant or serious infection, hospitalization and death.”
“They all do that, and they all do that very, very well,” he said. “So I’m not entirely happy with how sometimes this AstraZeneca vaccine is being portrayed,” he said, adding that it’s a “really good product.”
“And the best vaccine to take is the first one that becomes available to you,” he continued. “It doesn’t matter which one it is because they’re all really good.”
-With files from Global News’ Rachael D’Amore and The Canadian Press