OTTAWA — Canada's expert vaccine panel said Tuesday there is now enough "real-world evidence" to show the Oxford-AstraZeneca COVID-19 shot is both safe and effective for seniors.
The decision from the National Advisory Committee on Immunization (NACI) reverses its advice from March 1, when a lack of data for seniors in AstraZeneca's clinical trials prompted the panel to not recommend it be used for people over 65. It said seniors should instead be prioritized for shots from Pfizer-BioNTech and Moderna.
The new advice comes as authorities debate whether Canada is moving into a third wave of the pandemic, and investigate concerns about blood clots and AstraZeneca's vaccine.
Dr. Marc Berthiaume, director of the medical sciences branch at Health Canada, said the department is following the issue but currently sees no evidence of a safety concern.
"If we do hear that there's a specific risk, links to the AstraZeneca vaccine, then we will immediately take action," he said in French.
The European Medicines Agency is investigating a number of reports of patients developing blood clots, some of them fatal, within about two weeks of getting the AstraZeneca vaccine.
The agency said late Tuesday it is still reviewing reports from EU members, but "currently remains of the view that the benefits of the AstraZeneca vaccine in preventing COVID-19, with its associated risk of hospitalization and death, outweigh the risks of side effects."
Thrombosis Canada said last week evidence did not show a link between the vaccine and blood clots. AstraZeneca said Sunday a review of 17 million patient safety records following vaccination also did not show a link.
Many European countries have suspended the vaccine temporarily pending the review. That includes Germany and France, which initially stood by the vaccine after the first reports of blood clots.
Several of those countries are the same ones that earlier this month decided their initial advice not to give AstraZeneca to seniors was no longer sound, as new evidence on the widespread use of the vaccine on seniors showed it was quite effective.
That same evidence is what led NACI to change its advice as well. Its chair, Dr. Caroline Quach, said those studies weren't available when NACI developed its first guidance.
Most provinces heeded the warning two weeks ago not to give AstraZeneca to seniors, prioritized for doses across Canada because of their higher risk from COVID-19.
Provincial health authorities must now decide whether they will adjust their plans. Ontario Premier Doug Ford expressed frustration with the frequent changes.
"I can't begin to tell you the logistics behind it," he said. "It just messes everything up."
Provinces might have some leeway. Most of the first 500,000 doses of AstraZeneca delivered are already spoken for and more doses are not set to arrive in Canada until April.
Chief public health officer Dr. Theresa Tam said Tuesday the warning bells are sounding that a third wave of COVID-19 infections in Canada.
"We're watching, of course, that epidemic curve really carefully, because there is this upswing we're seeing now," she said.
Over the last week the average number of new cases per day was about 3,200, she said. That's up from 3,052 daily cases between March 5 and 11, and up from about 2,900 a day between mid-February and early March.
The death counts, however, have continued to drop, with an average of about 31 deaths a day in the last week, down from 41 a day a week ago, 52 at the beginning of March, and more than 80 in mid-February.
Tam said it's too soon to know if the death rate is falling because of vaccines, though she said provincial governments have reported the rates of COVID-19 among people over 80, who were in the first groups to get inoculated, are now below rates for other age groups.
"That suggests that the vaccines might have a good effect," said Tam.
Canada vaccinated almost 125,000 people Monday, the highest one-day total so far. More than 3.2 million doses have been given to date, with 2.6 million Canadians receiving at least one dose.
Tam said the existence of more contagious variants of the novel coronavirus brings added pressure and urged Canadians to remain careful even as vaccinations ramp up.
"This is not the time to increase your contacts," she said.
There are more than 3,400 confirmed cases of variants in Canada, more than 90 per cent the B.1.1.7 variant that first emerged in the United Kingdom, but Tam said they are just "the tip of the iceberg." There are potentially at least hundreds more cases screened for one of the mutations common to all variants, that have not yet been fully screened to identify which one.
Ontario's "science table" said Tuesday it believed almost half the new cases in that province are now variants.
Canada had some positive vaccine news Tuesday as Quebec-based Medicago announced it was beginning the Phase 3 trial of its vaccine here. It is the only Canadian company on the list of seven vaccines procured by the federal government, and the first Canadian-made vaccine to get to this stage.
Nathalie Landry, the executive vice president of scientific and medical affairs, said it is also enrolling people in the United States and up to nine other countries.
Landry said the hope is to report results by the summer, and approval by the fall. If that happens, she said, Medicago can deliver 20 million doses to Canada by the end of 2021.
Moderna also reported Tuesday it had begun dosing teenagers in a study of its vaccine on adolescents. Currently only Pfizer is approved for use on kids as young as 16.
It is hoped that children as young as 12 be approved for Pfizer and Moderna before schools resumes in the fall, but younger children aren't likely to be authorized until 2022.
This report by The Canadian Press was first published March 16, 2021.
— With files from Shawn Jeffords in Toronto
Mia Rabson, The Canadian Press