Tag Archives: blood

EU regulator places no new restrictions on AstraZeneca vaccine due to ‘possible’ blood clot link

The European Union’s drug regulator says it has found a “possible link” between the AstraZeneca-Oxford coronavirus vaccine and a rare blood-clotting disorder, but the benefits of the shot and the potential health consequences of suffering from COVID-19 still outweigh any risks.

The European Medicines Agency (EMA) said it would place no new restrictions on using the vaccine in people 18 and over, in both a statement and a subsequent news conference on Wednesday.

The EMA said most of the cases reported have occurred in women under 60 within two weeks of vaccination. The agency said based on the currently available evidence, it was not able to identify specific risk factors.

“The reported cases of unusual blood clotting following vaccination with the AstraZeneca vaccine should be listed as possible side-effects of the vaccine,” said Emer Cooke, the agency’s executive director.

Experts reviewed several dozen cases that came mainly from Europe and the United Kingdom, where around 25 million people have received the AstraZeneca-Oxford vaccine.

At a news conference from Brussels, Cooke said “the risk of mortality from COVID is much greater than the risk of mortality from these side-effects.”

Britain adjusts vaccine advice

The head of Britain’s drug regulator echoed that sentiment, but said on Wednesday people under 30 will be offered another product due to a rare blood clot risk.

The Pfizer-BioNTech and Moderna vaccines should be offered to people in that age group instead, the Medicines and Healthcare Products Regulatory Agency (MHRA) advised.

Dr. June Raine, the head of the MHRA, said the risk “remains extremely low” at “about four people in a million” who receive the shot.

WATCH | Britain’s Raine breaks down the number of cases:

The U.K.’s drug regulator says a rare side-effect from the AstraZeneca-Oxford COVID-19 vaccine has led to a change in its advice for what age groups should receive the shot. 1:33

Raine said that as of the end of March, there had been 79 reports, all after the first dose, out of approximately 20 million doses given within the U.K. Of the adverse reports, 51 came from women.

Raine said the British regulator had tracked 19 deaths among those reports, three of them in people under the age of 30. The regulator said the reports did not constitute proof that the inoculation had caused the clots.

Jonathan Van Tam, Britain’s deputy chief medical officer, characterized the new recommendation as a “course correction” not uncommon for the rollout of vaccines used in treating other illnesses.

“You can’t pick these kinds of things up until you’ve literally deployed tens of millions of vaccines,” he said.

According to reports in Britain, the majority of those under 30 have yet to be vaccinated.

In light of the follow up in Europe, the World Health Organization’s vaccine advisory committee said more specialized studies were needed into the blood clots.

“Based on current information, a causal relationship between the vaccine and the occurrence of blood clots with low platelets is considered plausible but is not confirmed,” the WHO committee said in a statement.

Canada already recommended shot for those 55 and over

The vaccine is one of five separate approvals so far during the pandemic from Health Canada, comprising two different sources.

Canada approved AstraZeneca-Oxford doses being manufactured in both Europe and in India, where it has been branded as Covishield. The vaccine first arrived in Canada in early March, and later that month, Ottawa announced it had received a loan from the United States of 1.5 million additional doses, as a hearing on the vaccine’s approval has yet to be held by American regulators.

Canada’s National Advisory Committee on Immunization (NACI) updated its recommendations in late March regarding the use of the AstraZeneca-Oxford vaccine in light of the blood clot reports seen in Europe. The committee recommended a pause in inoculating Canadians under 55 with that vaccine.

In its tracking of potential adverse events following vaccination, Health Canada has received no reports of the rare blood clotting in this country.

WATCH | Canada’s vaccine advisory committee adjusts AstraZeneca guidelines:

The European Medicines Agency says rare blood clots are a potential side effect of the AstraZeneca-Oxford COVID-19 vaccine, but it still says the benefits of the vaccine far outweigh the risks. 1:39

Dr. Shelley Deeks, co-chair of NACI, said at a virtual briefing on Tuesday that Canadian officials will study the updated data from their European counterparts to see if any advice needs to be updated.

She said it would be “premature” to say if the latest development in Europe will have any effect on confidence in the AstraZeneca-Oxford vaccine.

“What we’ve tried to be doing at NACI is actually being quite transparent about the evolution of the data so Canadians will have confidence that we are communicating what we know about safety, when we know it,” said Deeks.

The EMA is particularly focused on two types of rare blood clots: one that appears in multiple blood vessels and another that occurs in a vein that drains blood from the brain. It also evaluated reports of people who had low levels of blood platelets, which puts them at risk of severe bleeding.

Raine said 14 of the 19 fatalities noted were cases where cerebral venous sinus thrombosis with low platelets was present, while the other cases were associated with other kinds of thrombosis in major veins.

As recently as last week, the EMA said “there is no evidence that would support restricting the use of this vaccine in any population” — a response to several countries doing just that — though an expert said more brain clots were being reported than would be expected.

In March, more than a dozen countries, mostly in Europe, suspended their use of the AstraZeneca-Oxford vaccine over the blood clot issue. Most restarted — some with age restrictions — after the EMA said countries should continue using the potentially life-saving vaccine.

WATCH | European Union regulator says blood clot risk extremely rare:

Canada’s vaccine advisory committee has changed its advice and now says the AstraZeneca COVID-19 vaccine should only be given to people aged 55 and up following concerns it could be linked to a rare blood clot. 2:21

The suspensions were seen as particularly damaging for AstraZeneca because they came after repeated missteps in how the company reported data on the vaccine’s effectiveness and concerns over how well its shot worked in older people.

Cooke characterized the reports as evidence that caution and transparency have been guiding decisions.

“These very rare and unusual events were picked up, identified, analyzed and we have made a clear science-based recommendation to allow the safe and effective use of the vaccine,” she said.

Dr. Peter English, who formerly chaired the British Medical Association’s public health medicine committee, said the back-and-forth over the AstraZeneca vaccine globally could have serious consequences.

“We can’t afford not to use this vaccine if we are going to end the pandemic,” he said.

That’s because the vaccine is cheaper and easier to store than many others, is critical to Europe’s immunization campaign and a pillar of the United Nations-backed program known as COVAX that aims to get vaccines to some of the world’s poorest countries.

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British regulators increase number of blood clot cases after AstraZeneca vaccine to 30

British regulators on Thursday said they have identified 30 cases of rare blood clot events after the use of the AstraZeneca-Oxford COVID-19 vaccine, 25 more than the agency previously reported.

The Medicines and Healthcare products Regulatory Agency said it had received no such reports of clotting events following use of the vaccine made by BioNTech SE and Pfizer Inc.

The health officials said they still believe the benefits of the vaccine in the prevention of COVID-19 far outweigh any possible risk of blood clots.

Some countries are restricting use of the AstraZeneca vaccine while others have resumed inoculations, as investigations into reports of rare, and sometimes severe, blood clots continue.

On March 18, the U.K.’s medicines regulator said that there had been five cases of a rare brain blood clot among 11 million administered shots.

WATCH | Should people who’ve had the AstraZeneca vaccine be concerned?

Infectious disease experts take questions about the changing advice for the AstraZeneca COVID-19 vaccine including if those who’ve had a shot should be concerned. 4:22

On Thursday, it put the count at 22 reports of cerebral venous sinus thrombosis, an extremely rare brain clotting ailment, and eight reports of other clotting events associated with low blood platelets out of a total of 18.1 million doses given.

In Canada, the National Advisory Committee on Immunization recommended on Monday that the use of the AstraZeneca vaccine for Canadians under 55 be immediately suspended.

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Health Canada changes AstraZeneca vaccine label to add information about blood clots

Health Canada is updating the label on the AstraZeneca-Oxford and Covishield COVID-19 vaccines to add information about “very rare reports of blood clots associated with low levels of blood platelets,” but says the shot remains safe and that the benefits of getting the vaccine outweigh the risks.

“Health Canada reassures Canadians that the AstraZeneca COVID-19 vaccine continues to be safe and effective at protecting them against COVID-19 and encourages people to get immunized with any of the COVID-19 vaccines that are authorized in Canada,” the agency said in a statement Wednesday evening. 

It has also issued guidance for health-care professionals and vaccine recipients on the potential symptoms to monitor — including shortness of breath, chest pain, leg swelling and persistent abdominal pain — or a sudden onset of severe or persistent worsening headaches or blurred vision. 

No reports of clots in Canada 

All of Canada’s current supply of the AstraZeneca-Oxford vaccine is manufactured by the Serum Institute of India, which secured separate regulatory approvals from Health Canada.

That version, which is biologically identical to the AstraZeneca shot but manufactured under different conditions, has been branded as Covishield.

WATCH: Recommendations on vaccine not changing, Health Canada says 

Dr. Supriya Sharma, Health Canada’s chief medical adviser, says federal recommendations on the use of AstraZeneca’s COVID-19 vaccine are not changing at this point in time. 1:40

Health Canada says there have been no reports of clots following administration of the AstraZeneca-Oxford vaccine in this country. 

Several European countries suspended administration of the AstraZeneca-Oxford vaccine following reports of blood clots in a small number of patients. 

The European Medicines Agency (EMA) last week amended its authorization of the vaccine to say there is no overall increase in the risk of blood clots after getting the vaccine but added a warning that a small number of patients had developed rare blood clots in the brain after getting it.

At the time the EMA couldn’t say if the clots were related to the vaccine. German and Norwegian scientists have since said in a very small number of patients the vaccine is causing an extreme immune response that is leading to the clots. It is a treatable condition, they said.

The EMA reported 18 cases of cerebral venous sinus thrombosis, out of about 20 million people who received the AstraZeneca-Oxford vaccine in Europe, the United Kingdom, and India, and seven cases of another type of clotting disorder related to very low platelet counts.

Health Canada said it is aware that researchers in Europe have indicated that they have identified a possible cause for these very rare events, but says little information is available about the findings. “Health Canada will be reviewing this evidence when available,” it said in the statement. 

Canada has so far received about 500,000 doses of the vaccine and expects to get 1.5 million more as soon as this week from the United States.

Health Canada says minor and temporary side effects are common after all vaccinations, but that people should seek medical attention if they experience any new or worsening symptoms.


The new label will include information about a small number of clots experienced by patients who received the AstraZeneca-Oxford vaccine. (Jeff Stapleton/CBC)

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Is AstraZeneca vaccine safe for people who’ve had blood clots? Your COVID-19 questions answered

We’re still answering your COVID-19 questions. We’ve received more than 71,000 since the start of the pandemic. But vaccine questions are the main theme right now. We publish a selection of answers online and also put some questions to the experts during The National and on CBC News Network. Send your questions and stories to COVID@cbc.ca, and we’ll address as many as we can.

The AstraZeneca-Oxford COVID-19 vaccine has been in the headlines recently over concerns that some people were developing blood clots after receiving the shot. Some European countries suspended use of the vaccine, but many have since resumed.

You may be wondering what all of this means for you when it comes to taking the vaccine. Here’s what the experts are saying.

What are the latest findings on AstraZeneca’s safety?

A recent review from the European Union’s drug watchdog found the vaccine is not linked to an increase in the overall risk of blood clots. The European Medicines Agency (EMA) also concluded that the benefits of protecting against COVID-19 — which itself results in clotting problems — outweigh the risks.

At the same time, the EMA said it could not definitively rule out a link between the vaccine and specific, rare types of blood clots associated with thrombocytopenia, or low levels of blood platelets.

WATCH | AstraZeneca vaccine is safe, says EU drug regulator:

The AstraZeneca COVID-19 vaccine is safe and does not appear to cause blood clots, says the European Medicines Agency, after a review by an expert committee. But the EMA couldn’t rule out a link to blood clots entirely. 1:22

Specifically, it noted 18 cases of an extremely rare type of blood clot called cerebral venous sinus thrombosis (CVST), a condition that is much more common in women than men. Most of the incidents occurred within 14 days of receiving the AstraZeneca shot, and the majority were in women under the age of 55.

In its investigative document, the EMA said it would expect to see just 1.35 cases of CVST in the time period it looked at — but instead its researchers saw 12.

“A causal link with the vaccine is not proven, but is possible and deserves further analysis,” the agency said in its findings.

Around the same time the EMA released its report, researchers in Germany and Norway announced they had found a mechanism that could cause the AstraZeneca vaccine to create the blood clots in very rare circumstances, in addition to identifying a possible treatment for it.

Dr. Theresa Tam, Canada’s chief public health officer, acknowledged the possible link said in a statement on Sunday.

“It is possible that the vaccine may be associated with very rare but serious cases of blood clots associated with thrombocytopenia,” she said.

Overall, Health Canada has maintained that the benefits of the AstraZeneca COVID-19 vaccine continue to outweigh the risks. 

WATCH | Benefits of AstraZeneca vaccine outweigh risks, Tam says:

Canada’s Chief Public Health Officer Dr. Theresa Tam says the benefits of the AstraZeneca COVID-19 vaccine outweigh the rare risks. 1:53

Meanwhile, AstraZeneca announced on Monday that scientists found no increased risk of clots among the more than 20,000 people who received at least one dose of the shot in a late-stage study in the United States. The vaccine has not yet been given the green light in the U.S.

The company said the study also showed the vaccine provided strong protection against disease and complete protection against hospitalization and death across all age groups.

Is AstraZeneca safe for people with a history of blood clots?

Amid the developments, many readers are still wondering if having a history of blood clots means they’re at a higher risk of developing them after getting an AstraZeneca jab.

Some of the experts we spoke to said no, the vaccine is safe, even for people with a history of blood clots.

“Anyone who has a history of blood clots might have an increased risk of blood clots at any point anyway,” Dr. Lynora Saxinger, an infectious disease specialist at the University of Alberta in Edmonton, said in a recent CBC News interview.

“But I don’t believe that there would be a rationale to make a recommendation against using [the vaccine],” she said.


A medical worker receives a dose of the AstraZeneca vaccine in Taipei, Taiwan, on Monday. (Ann Wang/Reuters)

Dr. Cora Constantinescu, an infectious diseases specialist from the Vaccine Hesitancy Clinic at Alberta Children’s Hospital in Calgary, said if you are still worried about blood clots, you should be more concerned about catching the coronavirus than the vaccine.

“If you looked at five million people hospitalized with COVID-19, you would expect 100,000 to 500,000 of them to have clots,” Constantinescu said in a recent interview with CBC News Network.

“Keep in mind the risk of the disease itself is so much higher, and the more you wait to [get the vaccine], the less protected you are.”

On the other hand, Dr. David Fisman, an epidemiologist at the University of Toronto’s Dalla Lana School of Public Health, said Germany’s data offered a “compelling picture” that the rare blood clots were potentially linked to the vaccine in rare cases.

“I find myself in disagreement with Health Canada’s guidance on the use of AstraZeneca,” Fisman said.

“I do think that the use of this vaccine should be suspended in Canada until we have more data. At a minimum, I do not think it should be used in women aged 20 to 50 until we know more.”

Have blood clots been associated with the other vaccines?

If the overall rate of reported blood clots after AstraZeneca is no more than the rate in the general population, a number of readers, including Carolyn W., wanted to know why we’re not hearing similar issues with the Pfizer and Moderna vaccines.

“That’s a great question,” Constantinescu said.

In terms of a blood clot, she said, the numbers appeared similar “across the board” for all of the vaccines, including the mRNA vaccines.

Constantinescu tried to put the figures into perspective.

“If you took five million people, you would expect 5,000 to 15,000 cases of blood clots versus the 37 that were noted,” she said. “So if anything, even in the vaccinated population, there seemed to be a lower baseline rate than you would [have] in the general population.”

WATCH | Can AstraZeneca vaccine overcome mixed messaging, distrust?

Top U.S. infectious disease expert Dr. Anthony Fauci says interim data shows that the AstraZeneca-Oxford COVID-19 vaccine is 78.9 per cent effective overall. 1:05

There haven’t been any substantial reports of clotting during the clinical trials for the vaccines, Saxinger noted.

Most of the vaccine data has been “basically equal in the vaccine versus placebo recipient group,” she said. “And there certainly hasn’t been a strong population-based signal specifically for [deep vein thrombosis or pulmonary embolism] so far.”

What if you’re immunocompromised?

If you’ve got an autoimmune disease or are taking an immunosuppressant drug, it’s probably a good idea to talk to your doctor.

That’s because each condition is so different, Dr. Isaac Bogoch, an infectious disease physician in Toronto and a member of Ontario’s COVID-19 Vaccine Distribution Task Force, advised in an earlier article.

In general, the experts we spoke to said AstraZeneca is probably safe for immunocompromised people, but we’re still learning more.

The National Advisory Committee on Immunization (NACI), which makes recommendations on the use of newly approved vaccines in Canada, notes there is currently no data on COVID-19 vaccination in individuals who are immunosuppressed, as they were not included in the clinical trials.

“The concern is not so much about a safety issue,” Saxinger said, noting that AstraZeneca is considered as safe as any other non-live vaccine. You can read more about different types of vaccines here.


British Prime Minister Boris Johnson reacts after receiving his first dose of the AstraZeneca vaccine in London on March 19. (Frank Augstein/Reuters)

The real issue, Saxinger said, is “whether or not your particular immune change will allow you to get a fully protective response.”

“That’s where we’re still learning more.”

But even if immunocompromised people have slightly less protection than others, they should go ahead and get the vaccine, she said, because even a partially protective response against a severe COVID-19 infection is worthwhile.

Constantinescu added that it’s likely immunocompromised people may need booster doses in the future.

If you’re offered AstraZeneca, can you refuse?

Sure. No one is going to force you to take any one vaccine if you don’t want it. COVID-19 vaccines aren’t mandatory.

But that doesn’t mean you will immediately be offered another vaccine. That would depend on the province you live in, Constantinescu said.

For example, Quebec’s director of public health has said that people who refuse to take the AstraZeneca-Oxford vaccine will be bumped to the back of the line and have to make another appointment.

And waiting could be risky, especially as some provinces are seeing case counts rise, Constantinescu said.

“You are putting yourself at risk waiting for a different vaccine when we know that this vaccine works really well at preventing hospitalization, severity and death,” she said.

Have a question? 

Send your questions to COVID@cbc.ca

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Canada hesitates to update guidance on AstraZeneca-Oxford vaccine amid potential link to blood clots

This is an excerpt from Second Opinion, a weekly roundup of health and medical science news emailed to subscribers every Saturday morning. If you haven’t subscribed yet, you can do that by clicking here.


Scientists in Europe have reportedly found a link between the AstraZeneca-Oxford COVID-19 vaccine and extremely rare but potentially fatal blood clots, but Canadian public health officials have so far provided no update on guidance for the shot.

News broke on Friday that researchers in Germany and Norway said they had found a mechanism that could cause the AstraZeneca-Oxford vaccine to create the blood clots in very rare circumstances, in addition to identifying a possible treatment for it.

The finding comes after the European Medicines Agency (EMA) investigated 25 cases of the rare blood clots out of about 20 million AstraZeneca shots given and concluded on Thursday that the benefits from the vaccine far outweigh its possible risks, although a definitive link could not be ruled out.

The EMA said there was no increased risk from blood clots and that because the AstraZeneca-Oxford vaccine is effective in preventing COVID-19, which itself causes blood clots, the shot could actually reduce the risk of them overall.

But not all blood clots are the same, and 18 of the cases in Europe were of an extremely rare type called cerebral venous sinus thrombosis (CVST) — where veins that drain blood from the brain are obstructed and can potentially cause fatal bleeding.

Most of the incidents occurred within 14 days of receiving the AstraZeneca shot, and the majority were in women under the age of 55. It’s worth noting that this type of blood clot is much more common in women, particularly during and after pregnancy and while on birth control.

WATCH | Tam says benefits of AstraZeneca vaccine outweigh risks:

Canada’s Chief Public Health Officer Dr. Theresa Tam says the benefits of the AstraZeneca COVID-19 vaccine outweigh the rare risks. 1:53

Three of the seven patients in Germany who were recently vaccinated with the AstraZeneca-Oxford shot that had this rare brain blood clot have died.

In its investigative document, the EMA said it would expect to see just 1.35 cases of CVST in the time period it looked at — but instead its researchers saw 12.

Germany and Italy resumed vaccinations with the shot on Friday, but France opted to vaccinate only those over 55 with the AstraZeneca vaccine after discovering three cases of CVST. Denmark, Sweden and Norway decided to hold off on using the vaccine until at least next week, citing the need for more time to investigate.

Findings ‘need to be investigated’

“You cannot brush adverse effects under the rug. They always need to be investigated, and I think we have to look at this in a careful and critical manner,” said Dr. Isaac Bogoch, an infectious diseases physician and member of Ontario’s COVID-19 vaccine task force.

“We don’t have all the information yet and we’ll learn more about this — and I imagine we’ll see some updated guidance on who should get this vaccine and perhaps who shouldn’t be getting this vaccine.”

Health Canada released a statement on Thursday saying the benefits of the AstraZeneca-Oxford vaccine outweighed the risks and that the vaccine does not increase the “overall risk of blood clots,” but it provided no update on Friday when pressed for more comment on the evolving situation.

“As the vaccine rollout continues in Canada, Health Canada will continue to monitor the use of all COVID-19 vaccines closely,” the statement read.

“Health Canada will examine and assess any new safety concerns, and should a safety signal be confirmed, the department will take appropriate action.”

Researchers in Norway reported identifying the mechanism early Friday, saying it was due to a “powerful immune response” from the vaccine.


The AstraZeneca vaccine is prepared at the local vaccination centre in Hagen, Germany. Germany and Italy resumed vaccinations with the shot on Friday, the day after the European Medicines Agency found there was no increased risk of blood clots from the vaccine. (Kai Pfaffenbach/Reuters)

German researchers corroborated that finding, adding they had found a typical intravenous immunoglobulin treatment that can be offered to patients in hospitals if this rare type of blood clot occurs, but they said it wouldn’t work as a preventive measure.

“Of course you can’t completely undo a complication,” Dr. Andreas Greinacher, a professor of transfusion medicine at the Greifswald University Clinic, said during a news conference in Germany.

“But at least now we can offer the right treatment to be able to help as quickly as possible and as efficiently as possible.”

Potential blood clot link could alter rollout in Canada

The potential link could have massive implications on the rollout of the vaccine in Canada and other countries, after use of the shot was halted in parts of Europe over safety concerns in connection with the adverse events last week.

Health officials now face the unenviable task of either adjusting the rollout or trying to restore confidence in the shot, at a time when a variant-driven third wave is unfolding and many vulnerable Canadians are vastly underprotected from COVID-19.

The National Advisory Committee on Immunization (NACI) recommended earlier this month that Canadians over 65 not receive the shot, despite emerging evidence from around the world demonstrating its ability to prevent severe COVID-19 in older adults.

But that guidance changed on Tuesday after more real-world data on the vaccine’s effectiveness was reviewed by NACI, and CBC News broke the story revealing documents on the federal government’s plans to allow those 65 and older to receive it.

Experts say that while the guidelines for the vaccine could further change and it may not be recommended for certain age groups in the future, the protection against COVID-19 provided by the AstraZeneca-Oxford shot vastly outweighs the risk of rare adverse events.

That being said, we still don’t have all of the answers, and Canadians need to be aware of potential risks moving forward — however small they may be.

Medical experts in Canada divided over findings

Dr. Michael Hill, a professor of neuroscience at the University of Calgary’s Cumming School of Medicine, said on Friday that while the finding out of Europe is interesting, he remains skeptical of the potential link.

“For now, the case prevalence is such that it could still be a coincidence,” he said. “We just do not know.”

Hill said that as new data emerges, new questions will arise until there is enough evidence to meet the criteria to either confirm or deny a causal link to the vaccine.

WATCH | WHO finds AstraZeneca vaccine safe and effective:

The World Organization’s advisory committee on vaccine saftey says the AstraZeneca COVID-19 vaccine’s benefits outweigh the risks and the shot saves lives. 1:09

“The data will evolve further over time,” he said. “Meanwhile, a very large set of randomized trial data has shown no increased major adverse events with the AstraZeneca vaccine compared to placebo.”

Dr. David Fisman, an epidemiologist at the University of Toronto’s Dalla Lana School of Public Health, said German data offered a “compelling picture” that the rare blood clots were potentially linked to the vaccine in rare cases.

“I find myself in disagreement with Health Canada’s guidance on the use of AstraZeneca,” Fisman said.

“I do think that the use of this vaccine should be suspended in Canada until we have more data. At a minimum, I do not think it should be used in women aged 20 to 50 until we know more.”

Fisman said while the messaging around the AstraZeneca shot would be “challenging,” the continued use of the vaccine in the face of the issue that he believes will become “more apparent” as surveillance increases could erode trust in COVID-19 vaccines.

“I appreciate that this is a sunk cost and is politically difficult. I appreciate that vaccines have become a political football,” he said.

“That said, I think suspension of use of [AstraZeneca-Oxford] will create short-term discomfort but is the right thing to do in the longer term.”


In a statement on Thursday, Health Canada said it ‘will continue to monitor the use of all COVID-19 vaccines closely,’ noting that the benefits of the AstraZeneca-Oxford vaccine outweigh the risks. (Hannibal Hanschke/Reuters)

Dr. David Juurlink, head of clinical pharmacology at Sunnybrook Health Sciences Centre in Toronto, said the rare events may signal a causal link with the vaccine but need to be put in context even if they are confirmed.

“If people are foregoing vaccination — AstraZeneca or otherwise — because of fear of some infinitesimally rare adverse effect, they run the risk of dying,” he said.

“I think it’s probably fair to make the claim that the countries in Europe that went against the advice of their regulator and suspended the use — that may cost some of their citizens in those countries their lives.”


To read the entire Second Opinion newsletter every Saturday morning, subscribe by clicking here.

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AstraZeneca says its vaccine review found no evidence of increased blood clot risks

AstraZeneca Plc on Sunday said it had conducted a review of people vaccinated with its COVID-19 vaccine which has shown no evidence of an increased risk of blood clots.

The review covered more than 17 million people vaccinated in the European Union and United Kingdom.

“A careful review of all available safety data of more than 17 million people vaccinated in the European Union and U.K. with COVID-19 Vaccine AstraZeneca has shown no evidence of an increased risk of pulmonary embolism, deep vein thrombosis or thrombocytopenia, in any defined age group, gender, batch or in any particular country,” the statement said.

Authorities in Denmark, Norway, Iceland and the Netherlands have suspended the use of the vaccine over clotting issues, while Austria stopped using a batch of AstraZeneca-Oxford shots last week while investigating a death from coagulation disorders.

Ireland on Sunday temporarily suspended AstraZeneca’s COVID-19 vaccine “out of an abundance of caution.”

The drug maker said additional testing has and is being conducted by the company and the European health authorities and none of the re-tests have shown cause for concern.

There are also no confirmed issues related to quality of any of its COVID-19 vaccine batches used across Europe and rest of the world, the company said.

Health Canada says no issues with vaccine reported

While other countries paused use of the vaccine, Health Canada has maintained there is “no indication” the vaccine causes blood clots, adding that no adverse events from AstraZeneca doses have been reported in Canada so far.

“Health Canada authorized the vaccine based on a thorough, independent review of the evidence and determined that it meets Canada’s stringent safety, efficacy and quality requirements,” the department said on March 11. 

Canada is one of many countries, including Germany, France, Poland, Nigeria, and the United Kingdom who continue to use the vaccine, citing a lack of any evidence of a link to blood clots.

WATCH | Reassurance on safety of AstraZeneca-Oxford’s vaccine:

Despite some European countries temporarily halting use of the AstraZeneca-Oxford vaccine after 30 cases of blood clots, experts maintain it is still safe to use in Canada. 2:01

There has been some confusion, however, related to Canada’s position on who should take the AstraZeneca-Oxford vaccine.

The National Advisory Committee on Immunization (NACI) recommended last week that Canadians over 65 not receive an AstraZeneca-Oxford vaccination despite emerging evidence from countries around the world demonstrating its ability to prevent severe COVID-19 in older adults.

The recommendation led provinces to reorganize their vaccination plans for seniors. The result was people aged 60-64 could receive AstraZeneca-Oxford shots ahead of older age groups, who are at greater risk of hospitalization and death from COVID-19.

Quebec is the only province so far to ignore the national recommendations. Officials there said this week they would administer the AstraZeneca-Oxford vaccine to seniors in direct contrast to what the province considers outdated NACI advice.

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U.S. to put limits on flood of COVID-19 blood tests after lax oversight

U.S. regulators Monday pulled back a decision that allowed scores of coronavirus blood tests to hit the market without first providing proof that they worked.

The Food and Drug Administration said it took the action because some sellers have made false claims about the tests and their accuracy. Companies will now have to show their tests work or risk having them pulled from the market.

Under pressure to increase testing options, the FDA in March essentially allowed companies to begin selling tests as long as they notified the agency of their plans and provided disclaimers, including that they were not FDA approved. The policy was intended to allow “flexibility” needed to quickly ramp up production, officials said.

“However, flexibility never meant we would allow fraud,” Dr. Anand Shah, an FDA deputy commissioner, said in a statement. “We unfortunately see unscrupulous actors marketing fraudulent test kits and using the pandemic as an opportunity to take advantage of Americans.”

Blood tests are different from the nasal swab tests currently used to diagnose active COVID-19 infections. Instead, the tests look for blood proteins called antibodies, which the body produces days or weeks after fighting an infection. Most use a finger-prick of blood on a test strip.

The revised policy follows weeks of criticism from doctors, lab specialists and members of Congress who say the FDA’s lack of oversight created a Wild West of unregulated tests.

The agency acknowledged Monday that there have been problems with deceptive, false marketing among the 160 tests that have been launched in the U.S. Some companies have claimed their tests can be used at home, although FDA has not allowed that use. Others make unsubstantiated claims about their accuracy. Some U.S. hospitals and local governments have reported buying tests that turned out to be inaccurate or frauds.

So far, the FDA has granted authorization to 11 antibody tests, meaning their methods, materials and accuracy passed muster with agency regulators. Companies currently on the market without FDA authorization will now be required to submit their formal applications to regulators within 10 business days. Companies that launch at a later date will similarly have 10 days to turn over their applications after validating their tests. 

Test findings unclear

Health officials in the U.S. and around the world have suggested the tests could be helpful in identifying people who have previously had the virus — with or without getting sick — and developed some immunity to it. But researchers haven’t yet been able to answer key questions that are essential to their practical use: what level of antibodies does it take to be immune and how long does that protection last?

“We’re spending a lot of time and resources on something that is not really a panacea for reopening,” said Kamran Kadkhoda, a lab director at the Cleveland Clinic. 

For now, the tests are mainly a research tool for scientists trying to determine how widely the coronavirus has spread among the U.S. population. Those studies are underway but have produced widely different preliminary results, in part, due to variations between tests. Even high-performing tests can produce skewed results when used in a large population where few people have had the virus. 

The National Institutes of Health and other federal agencies are also reviewing tests and conducting research into whether they can successfully predict immunity in patients.


Stephen Hahn, commissioner of food and drugs at the U.S. Food and Drug Administration, said that their criteria for tests has shifted. The FDA originally allowed unapproved tests to be sold in order to quickly ramp up production. (Sarah Silbiger/Getty Images)

FDA Commissioner Stephen Hahn said in a statement that the government’s approach to “balancing of risks and benefits has shifted from where it was in mid-March” based on new data from FDA and NIH reviews.

Monday’s move is the latest in the Trump administration’s fitful attempt to roll out an effective, comprehensive approach to testing. While testing has ramped up since the outset of the outbreak, state and local governments continue to report shortages of testing supplies needed to screen for the virus and safely ease social distancing measures.

A “testing blueprint” released last week by the White House emphasized that states are responsible for developing their own testing plans.

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Health Canada says rapid blood test for COVID-19 remains under review

Health Canada says a rapid coronavirus blood test that’s being manufactured in Canada and shipped to the United States is not ready for use here.

CBC News has learned that tests such as the one made by Markham, Ont., company BTNX are on hold in this country, despite the fact that sales of the same test have been allowed to proceed in the U.S., the U.K. and Europe.

The company’s chief financial officer, Mitchell Pittaway, said in an email to CBC News that Health Canada told the company rapid blood tests of the kind it’s seeking to sell will remain under review until a “greater national strategy on their use is developed.” 

“I will say that we were quite disappointed by that feedback,” said Pittaway, noting that the company has been able to sell “tens of thousands” of the tests to the U.S. through an emergency program that exempts it from normal regulatory processes.

CEO Iqabal Sunderani said, “We have a sister company in the U.K. that is literally selling this in the millions. It would be good to have a base in your home country.”

While Canada’s medical laboratories have been working through a backlog of tests done through nasal swabs, blood tests that could hasten diagnosis remain off the table here.


BTNX, located in in Markham, Ont., is shipping thousands of its rapid blood tests to hospitals in the U.S. (BTNX Inc.)

Unlike the traditional swabs that test for the presence of the virus, these rapid tests use just a couple of drops of blood from a pinprick on the finger to detect the presence of antibodies that fight the virus. With no trip to a laboratory required, results are available on the spot in 15 minutes.

The tests cost around $ 10 each.

While they can’t detect the virus in its early stages — as nasal swabs can — the rapid blood tests are effective at diagnosing people about five to seven days after symptoms show up, once the body has had a chance to produce antibodies. 

The test can also help identify who is immune to the illness — including people who have had the illness, as well as some who may have acquired the virus but never become sick.

Dr. Jean Carruthers, a Vancouver ophthalmologist and ocular plastic surgeon, wrote a letter to the federal government after learning about the BTNX test. It’s been co-signed by 90 physicians.

WATCH | Ottawa urged to fast-track new rapid coronavirus test

Ottawa is being urged to fast-track trials of a new, faster way of testing for coronavirus being employed widely on a trial basis in other countries. 1:49

“To know that you’re immune and can go back to work and can help your fellow Canadians makes a ton of sense,” said Carruthers. “I’m really disappointed that we have a test made in Canada by Canadians that can’t be used on Canadians.”

Carruthers cited Germany and South Korea as good examples of countries that have used rapid blood tests systematically to identify who can safely go back to work in front-line health care and the service industry, rather than have huge swaths of workers on pause. Those cleared can also help trace the contacts of people who have been infected — something routinely done when a patient tests positive.


Infectious disease expert Dr. Michael Gardam said using this kind of test to identify who has immunity to the disease could help Canada back off the ‘sledgehammer’ of strict physical distancing measures currently in place. (Craig Chivers/CBC)

Dr. Michael Gardam, an infectious disease specialist and the chief of staff at Humber River Hospital in Toronto, echoed that sentiment.

“It would allow us to back off from the sledgehammer, and we could be much more selective in the kind of control measures that we’re bringing into play, because we can’t keep doing what we’re doing now for all that much longer.”

In an email to CBC News, Health Canada said it is following the advice of the World Health Organization, “which does not currently recommend serological [blood] tests for clinical diagnosis.”

“The department is working with the National Microbiology Laboratory to validate testing and research, along with expert advice, so that we can have confidence in the test results,” the email said.

At BTNX, Pittaway said he hopes a different answer comes soon.

“We’ve seen the speed in which other other health agencies around the world have been able to take these decisions. and we think that Canada will hopefully be in a position to take a well-informed decision quite quickly.” 

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Why Canada is taking so long to start testing blood for COVID-19

With shortages of masks, gloves and testing kits hampering the fight against the coronavirus in Canada, there is one important weapon that remains unused — rapid blood tests that will tell within 15 minutes if someone has been exposed.

These tests cannot detect early infections because the body’s immune system hasn’t had time to produce antibodies against the virus. But about five to seven days after symptoms show up, they could be used to determine who has been infected and who has not — which would provide a more accurate picture of Canada’s epidemic, including identifying people who were asymptomatic or had only mild infections.

The rapid blood tests are already being used in Europe, Asia, Australia and the U.S. Some academic laboratories are also developing COVID blood tests.

But so far none of those tests has been approved for use in Canada.

One company, BTNX Inc., in Markham, Ont., is shipping thousands of rapid tests to hospitals in the U.S. 

Mitchell Pittaway, the company’s chief financial officer, said he would rather be distributing the tests in Canada.

“The response [from Health Canada] has been a bit longer than what we would have liked to have seen,” Pittaway said. “The U.S. has been much quicker.”

Similar to blood glucose test

This week his company shipped 20,000 tests to U.S. hospitals. It will be sending another 200,000 to the U.S. next week.

“As a Canadian company with Canadian staff, ideally we would love to have all of this capacity blocked off for Canada, but we’re not able to step back and not address needs coming from other countries.”


BTNX Inc., in Markham, Ont., is one of several companies awaiting approval of rapid blood testing technology in Canada. Meanwhile, BTNX is shipping thousands of its tests to hospitals in the U.S., where approval was fast-tracked. (BTNX Inc.)

The test kit sells for about $ 10 US and it uses a simple finger-prick of blood to reveal whether someone has been infected with SARS-CoV-2, the virus that causes COVID-19.

“It’s similar to a blood glucose test,” said Pittaway. “Put a droplet of blood in the sample well, followed by two droplets of buffer, and after 15 minutes there will be a reaction.” That’s if the person has been infected with COVID-19. There will be no red lines on the test paper if there are no antibodies detected in the blood.

The company reports that the test is highly sensitive and specific for the COVID-19 virus, but does not recommend it as stand-alone confirmation of an infection, and the test can be complicated if a person has been infected by milder coronavirus strains.

Still, Pittaway said the test could help reduce the current strain on the laboratory testing system by prioritizing anyone who gets a positive result on the blood test.

Health Canada reviewing

There is a risk of false positives and false negatives with any test. That’s one reason Health Canada is taking a close look at the rapid blood tests before approving them for use in Canada

“The department is working with the National Microbiology Laboratory to validate testing and research, along with expert advice, so that we can have confidence in the test results,” Health Canada spokesperson Geoffroy Legault-Thivierge said in an email.

In the U.S., the FDA granted expedited approval for their use by health care professionals only.

“And that’s the same as we’re pursuing in Canada,” said Pittaway There are more than a dozen companies ready with blood tests and waiting for Health Canada to give them the go-ahead.

“Our application to Health Canada was submitted and under review,” Bryan Fang, a spokesperson for Healgen Scientific said in an email. “Health Canada will release the information once it is approved.”


An illustration of Healgen Scientific’s rapid COVID-19 blood test, which has been approved for use in the U.K., France and Italy, and is awaiting approval in Canada. (Healgen Scientific)

Fang said his company received European approval back in February to supply a rapid COVID-19 test to the U.K., France and Italy. 

“We are increasing our capacity every day,” Fang said Wednesday. “As of today, we can make 500-600K per day.”

Swab test kits prioritized

Two weeks ago, Canada’s health minister signed an interim order to speed up approvals for COVID-19 tests and other medical devices. Rapid blood tests are being considered under that order

“These tests are also being accepted for review; however, the World Health Organization does not currently recommend serological tests for clinical diagnosis, and Health Canada is following this advice,” said Legault-Thivierge, adding that Health Canada officials are giving the traditional PCR (polymerase chain reaction) testing kits priority under the interim order.


The laboratory-based PCR test, like the one pictured, is the only one that can detect an infection in the early stages, using a nasal swab inserted into a patient’s nose. (Evan Tsuyoshi Mitsui/CBC)

The laboratory-based PCR test is the only one that can detect an infection in the early stages, using a nasal swab inserted into a patient’s nose. That sample is sent to a hospital or provincial lab, where specialized machines try to detect the virus’s genetic material.

But a cross-Canada shortage of testing kits, machines and trained laboratory staff means many COVID-19 cases are being missed, and provincial case counts are underestimating the extent of the epidemic in Canada.

People are still shocked to learn that they might not be tested despite having symptoms or being in close contact with someone who is infected. Even in nursing homes with active COVID-19 outbreaks, Ontario is still only testing people with symptoms.

Dr. Samir Sinha, director of geriatrics at Toronto’s Sinai Health Systems, told CBC Toronto’s Mike Crawley that everyone in an affected long-term care facility should be tested.

“That’s important so that we don’t miss cases that could allow us to further spread this virus around and potentially kill more people,” he said.

Across Canada, researchers are scrambling to increase PCR testing capacity. At the University of Toronto, Keith Pardee is developing a portable test system that uses different chemicals than the ones currently running short. His test is not yet approved for use, but he hopes to have patient trials completed by early next month.

At the University of Calgary, Dr. Dylan Pillai is developing another alternative to the PCR test that would also be portable and use different chemicals. He said he could be ready within two weeks to help take the load off the laboratories.

“We have a working assay already developed and we’re just in the process of validating that,” he said.

With new research suggesting there could be a substantial number of people infected without showing any symptoms, experts are increasingly recommending the use of population-wide rapid blood tests as an important tool in the process of returning to normal. The blood tests will reveal how many people have already been exposed, and could therefore be expected to have at least some short-term immunity to the virus.

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Researchers Create AI-Powered Blood Test to Detect Cancer

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Cancer is one of the most common causes of death, but the huge variation in types of cancer can make early detection a challenge. A team of researchers from the US has developed a blood test that might be able to help identify early-stage tumors using the power of AI. The test can detect over 50 different cancers and narrow down tumor location to specific areas of the body. 

At its most basic, cancer is uncontrolled cell growth. There are many different types of cells in the human body, and almost all of them can become cancerous. Unfortunately, many cancers don’t present with noticeable symptoms until the disease has progressed to the later stages. Once cancer begins spreading to other body systems, it becomes much harder to treat. 

A routine test that could flag potential cancers early on could save untold lives and reduce medical costs. The team, consisting of researchers from the Mayo Clinic, Cleveland Clinic, and other institutions, focused on analyzing signals from so-called “cell-free DNA” (cfDNA). That’s genetic material shed by cells that circulates freely in the blood. All cells leak a little DNA, and that includes the cells in tumors. 

While cancer does involve genetic alterations, those changes are minor and often limited to specific sections of DNA. A better way to spot the evidence of cancer in cfDNA is by assessing methylation patterns. In methylation, a methyl group (CH3) replaces a hydrogen atom on cytosine or adenine — those are two of the four base pair molecules that make up your genetic code. Methylation can affect the way your genes are expressed without actually changing the underlying sequence. Importantly, methylation can be a cause or result of cancer. 

The team started with blood samples from 3,000 patients, half of which had one of the 50+ cancers included in the study. This was “labeled” data, allowing the AI to learn the methylation patterns in cfDNA for various cancers and for no cancer. To test the algorithm, researchers put to work categorizing 1,200 new samples, and the results are encouraging. 

The AI is able to detect 93 percent of stage IV cancers, 81 percent of stage III, 43 percent of stage II, and 18 percent of stage I tumors. The rate of false positives was just 0.7 percent. When it spotted cancer, the AI was able to identify the location of the tumor with 93 percent accuracy. 

The team is hopeful this technique could scale to larger populations. Detection of early cancers is still low, but those tumors are rarely found via other means. Identifying 18 percent of cancers early could still be very helpful, and additional training could make the AI better at detecting cancer in the early stages.

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