Health Canada confident AstraZeneca vaccine safe and effective against COVID-19

OTTAWA — Health Canada is reassuring Canadians the Oxford-AstraZeneca vaccine is safe and effective, even as it works to add a warning about blood clots and reacts to a new controversy over the company’s preliminary data results in the United States.

The latest vaccine confusion comes as new daily cases of COVID-19 are up 15 per cent across Canada in the last week, prompting some provinces to prepare for new lockdowns or warn they’re coming if people aren’t more careful.

Saskatchewan is sending Regina and some surrounding municipalities back into a full lockdown, banning household guests immediately and putting a stop to indoor dining at restaurants and all other non-essential indoor activities on Sunday. 

Regina reported 91 new cases Tuesday, driven by variants of concern.

Quebec Premier François Legault warned some regions in that province to cut back on their in-person contacts or risk new restrictions.

Chief public health officer Dr. Theresa Tam said tightening public health measures might be necessary again, particularly as hospitalizations and critical care patient loads are creeping back up.

“As vaccine delivery begins to ramp up at an accelerated pace, there are hopeful signs for better days ahead,” she said. “However, increasing case counts, a rising proportion of new variant cases and shifting severity trends are cause for continued caution.

In the last week, she said an average of 2,100 people were in hospital in Canada being treated for COVID-19 on any given day, including 580 in critical care. That compares to 2,040 in hospital and 550 in ICUs a week ago.

Canada’s vaccine program is accelerating, with more than two million doses expected this week. It’s the most in a single week so far and could get even bigger if 1.5 million doses of the Oxford-AstraZeneca vaccine arrive from the United States.

But that vaccine is once again in a negative spotlight, this time over accusations within the United States that the company’s preliminary trial results reported Monday were misleading.

It is another blow for a vaccine that has now faced everything from a mistake in dosing during early trials, lower efficacy results than its main competitors, confusion about whether it is effective for seniors, and reports it might cause a rare type of blood clot in the brain in a very small number of patients.

Health Canada’s chief medical adviser Dr. Supriya Sharma said the U.S. trial issue hasn’t affected Canada’s authorization, which was given Feb. 26 based on trials in the United Kingdom and Brazil.

Those trials showed the vaccine was 62 per cent effective against COVID-19 infections and entirely prevented hospitalizations and deaths.

Monday, the company reported preliminary results from a trial in the United States that appeared stronger, saying it was 79 per cent effective against infection. That report prompted the independent monitoring board overseeing the trial for the U.S. National Institutes of Health to accuse the company of reporting incomplete data to show a better result.

The board members said their analysis pegged the vaccine’s efficacy at between 69 per cent 74 per cent, and said the company’s decision to issue a press release with better results erodes public trust.

AstraZeneca said in a statement Monday’s preliminary report was accurate with data until Feb. 17, and that its analysis of more recent results are consistent with the preliminary report. It said it plans to issue its report on the updated data within 48 hours.

Sharma said it’s not unusual for companies to report preliminary data but said in this case the report came when the company was a lot closer than is typical to knowing what the final data shows. Still, she said, Canada approved the vaccine based on other trials and this doesn’t change those findings.

“At this point in time, we, of course, believe that the benefits of the AstraZeneca vaccine continue to outweigh the risks,” she said. 

Health Canada expects to receive the U.S. trial data within the next few weeks and Sharma said it will be reviewed thoroughly and the findings communicated to Canadians.

Health Canada is working on adding a warning to the Canadian label on the vaccine because of the possible, though rare, risk of blood clots.

The European Medicines Agency added such a warning last week after reports that 38 people developed blood clots, out of almost 20 million people who were vaccinated.

The warning says the overall risk of blood clots is not heightened by the vaccine but it may cause a very rare blood clot in the brain. Scientists in Germany and Norway said they believe they have identified the cause as an extreme immune reaction, but said it is treatable and very rare.

Sharma said symptoms would include sudden, intense or persistent headaches, shortness of breath and pain or tenderness in the legs.

But she says there are concerns that this vaccine is suffering in public confidence.

“We’ve said this many times before, that even the most effective vaccine only works if people trust it and agree to receive it,” she said. “It’s like any other reputation — once there’s some doubt that creeps into that reputation, it’s that much more difficult to gain that back.”

More than 3.5 million people in Canada have received at least one dose of vaccine now, and most provinces expect to be able to offer a first dose to every adult by the end of June.

The most positive news on the Canadian COVID-19 front came out of Nunavut Tuesday, which declared itself to be COVID-19 free again, after a lengthy outbreak.

Health officials in British Columbia said Tuesday an accelerated timeline for its immunization plan would allow about 200,000 more people who are clinically extremely vulnerable to get their vaccine early. 

Those with various forms of cancer, transplant recipients and severe respiratory conditions can start booking on Monday alongside the current age-based vaccine program. 

This report by The Canadian Press was first published March 23, 2021.

Mia Rabson, The Canadian Press