The AstraZeneca vaccine, blood clots and VIPIT: What you need to know

The AstraZeneca vaccine, blood clots and VIPIT: What you need to know
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TORONTO -- Canada’s National Advisory Committee on Immunization (NACI) has recommended pausing administration of the AstraZeneca coronavirus vaccine to those under the age of 55 due to fears of recipients getting a rare type of blood clot called vaccine-induced prothrombotic immune thrombocytopenia (VIPIT).

Several provinces, including Alberta, Manitoba, Ontario and Quebec, announced they would follow the guidance, which NACI said stems from pending investigations of VIPIT cases in Europe.

It was believed that VIPIT occurred in about one per million administered vaccines, according to the World Health Organization (WHO), but a report from the Paul Erlich Institute in Germany cited potential numbers closer to one in 100,000 doses.

European cases of VIPIT have been primarily reported in women under the age of 55, with a few cases in men.

VIPIT refers to a specific type of blood clot that can stem from receipt of the AstraZeneca vaccine and is different from the blood’s regular clotting mechanism or conditions like deep vein thrombosis.

“A blood clot is what you see when the blood coagulates, the platelets stop the bleeding after someone has cut themselves - it s a response of the body to injury,” said clinical researcher and Toronto physician Dr. Iris Gorfinkel in a telephone interview with Monday. “It’s really common and it s necessary.”

“But what happens from certain disease states, and that s one of the concerns around the AstraZeneca vaccine, is whether it will cause the blood to clot that s not in a good way, but in a bad way that actually causes…a blood clot to develop in an area and block the blood vessel, and that blood vessel will no longer bring oxygen and nutrients to the area it’s supposed to,” Gorfinkel explained.

VIPIT symptoms usually occur between four and 20 days after vaccination and include persistent and severe headaches, seizures, blurred vision, shortness of breath, chest or abdominal pain and redness in a limb, according to

The advisory states that VIPIT is very rare and it’s not known if certain patients are more likely to get the condition.

At this time the group states they “do not believe that VIPIT is more common in people who have had blood clots before, people with a family history of blood clots, people with low platelet counts or pregnant women because VIPIT does not develop through the same process as usual types of bleeding or clotting problems.”

A statement from the Public Health Agency of Canada (PHAC) said VIPIT can have serious outcomes, but early diagnosis and treatment can help prevent that.

“Based on current evidence, for those individuals who have already been vaccinated with AstraZeneca for more than 20 days there is no cause for concern,” PHAC said. “For those who have been vaccinated with AstraZeneca less than 20 days, and anyone vaccinated with the AstraZeneca vaccine going forward, you should seek immediate medical attention in the rare event that you develop symptoms starting four days or more after vaccination.”

Some doctors are sounding the alarm over the new data.

“These are not ordinary blood clots, they can cause very serious disease in the brain and they can be fatal,” infectious disease specialist Dr. Abdu Sharkawy told CTV News Channel’s Power Play on Monday.

“Even though they are extremely rare, they re very serious and it begs an explanation, it begs an investigation to make sure that if you are going to roll it out potentially over a scale of millions and millions of people, you certainly don t want to put them in harm s way.”

Gorfinkel said it’s very difficult to track down the “why” of rare possible vaccine side effects like VIPIT.

Gorfinkel also urged people to do research before panicking and said a lot of the answers for NACI’s decision making lies in the math.

“The numbers that we re seeing [of VIPIT] are so far and few between that you will be very hard pressed to find a doctor who s ever seen a case,” she said. “So consider that the World Health Organization estimates this to be one in a million. A regular doctor has maybe 1,500 patients - so how many doctors would it take to get to that million? The answer is way more doctors than I personally even know.”

Gorfinkel said that health agencies may be “worried” about the findings from the Paul Erlich Institute, but said what they “all agree on” is that blood clots are rare.

“It s extremely rare after getting the shot…but the World Health Organization has landed squarely on the [fact that] benefits outweigh the risks, and the European Medicines Agency has said the benefits outweigh the risks, but why NACI is recommending a pause is a little more complicated and it has to do with math,” she said.

Because health organizations can only give the vaccine at a certain rate due to supply chains and dosage schedules, Gorfinkel said that NACI is asking the question, “‘can we make do with the vaccines that we have for the population who is most risk right now and still get the information we need for the younger people?’”

But Gorfinkel added that the “numbers change completely” if the World Health Organization’s estimate of one in a million VIPIT cases is correct versus the Paul Erlich Institute’s one in 100,000.

“If it s as high as one in one hundred thousand, this is where NACI is drawing the line in the sand, and saying they need to look more closely at it,” Gorfinkel said, adding that because cases of VIPIT are so few and Canada’s population so varied the question becomes: “Is that data necessarily even translatable to what s happening here?…we cannot be sure of that.”

Gorfinkel said some of NACI’s decision making comes to down to the fact that Canada has alternatives to offer instead of the AstraZeneca vaccine.

“NACI’s thoughtfully asking the question, ‘could we not just vaccinate with these others options?’” Gorfinkel said. “This is ultimately why we have Health Canada, why we have NACI and you know, the way it works is Health Canada is a ‘yay or nay,’ is it ‘in or out,’ and NACI does the finer details on it. And generally speaking, the provinces and territories will follow exactly what NACI suggests.”

Despite Monday’s announcement, NACI has recommended the continued use of the AstraZeneca vaccine among people over the age of 55 with informed consent, due to the lower risk of developing of VIPIT in older populations and the increased risk of severe COVID-19 infections among that age group.
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