A vial of some of the AstraZeneca COVID-19 vaccine is shown at a facility in Milton, Ont., on Wedneday, March 3, 2021. THE CANADIAN PRESS/Carlos Osorio - POOL

A vial of some of the AstraZeneca COVID-19 vaccine is shown at a facility in Milton, Ont., on Wedneday, March 3, 2021. THE CANADIAN PRESS/Carlos Osorio - POOL

What do you do if you think you have VITT? What we know of the rare clotting disorder

Risk of VITT has been estimated as anywhere from one case in 50,000 doses given, to one in 250,000

A new blood-clotting syndrome seen in a small minority of COVID-19 vaccine recipients continues to draw significant attention, but experts maintain the event is exceedingly rare — and treatable, in most cases.

Vaccine-induced thrombotic thrombocytopenia, or VITT, has been identified in a handful of Oxford-AstraZeneca recipients in Canada, causing death in one patient.

Dr. Jeff Weitz, the executive director of the Thrombosis and Atherosclerosis Research Institute (TAARI) at McMaster University, says doctors are learning more about VITT every day.

And that’s good news for those worried about potentially developing the disorder, which is so new a definitive link to the AstraZeneca shot hasn’t been confirmed.

“We now know how to diagnose this and we know how to treat it,” Weitz said. “So even if you are one of those unfortunate, rare individuals — maybe four out of a million — who get it, we know what to do.”

Experts maintain the benefits of vaccinations far outweigh the small risk of the clots, with Weitz noting that clots have been detected far more often in COVID-19 patients.

Here’s what we know about VITT:

HOW OFTEN DOES IT HAPPEN?

The risk of VITT has been estimated as anywhere from one case in 50,000 doses given, to one in 250,000.

Thrombosis expert Dr. Menaka Pai said that range is due to different reporting standards around the world.

Pai said one in 50,000 to one in 100,000 seems to be an appropriate range, but those numbers can change as more vaccines are administered globally.

“Every day we’re giving more shots, and of course, doctors are surveilling for cases, so it’s literally changing every hour,” she said.

Seven cases were reported in Canada as of Tuesday, out of some 1.7 million doses of AstraZeneca’s viral vector product given as of April 24.

Meanwhile, 17 cases of VITT had been confirmed as of April 23 in the United States — out of more than eight-million doses of Johnson & Johnson’s viral vector vaccine. AstraZeneca is not approved in the United States, and Johnson & Johnson, though authorized in Canada, has not yet been used here.

Dr. Michael Hill, a stroke research expert and clinical neurosciences professor at the University of Calgary, said the worry is understandable.

He suggested people look at it the other way around — a recipient of an AstraZeneca or Johnson & Johnson shot has 99,999 out of 100,000 odds of being completely fine, with the added benefit of excellent protection from severe COVID-19.

“The risk (of getting VITT) is real, it’s not zero,” Hill added. “But on the other hand, nothing we do has zero risk.”

WHAT’S CAUSING VITT?

Pai said the disorder appears to be an immune response to viral vector vaccines. As antibodies are produced within four to 28 days of the jab, platelets somehow get “switched on”in a small number of people.

“You get this immune phenomenon that causes low platelets, and it gives you very aggressive blood clots,” she said.

Pai said it’s not clear why a minority of recipients are affected and others are not.

Previous blood clots or family history of clots don’t appear to hold significance, she said, nor does being on the birth control pill — which carries its own clotting risk of about 5 in 10,000.

Gender also doesn’t seem to indicate who’s more susceptible to VITT, Pai added.

“At first they thought women were much more likely to get it, but now we’ve learned that there’s likely only a slight predisposition,” she said.

WHAT ARE THE SYMPTOMS TO WATCH FOR?

A number of wide-ranging symptoms could be signs of VITT if they occur four to 28 days after receiving a viral vector vaccine, Pai said.

They include: persistent and severe headache, difficulty moving parts of your body,seizures, blurred or double vision, shortness of breath, or back, chest or abdominal pain. Significant changes in a limb — swelling, redness, a pale appearance or cold feeling in an arm or leg — could also indicate clotting.

Hill said clots typically appear in the head, lungs, legs or stomach, so symptoms associated with those body parts should not be ignored. Weitz added that some VITT clots have been seen in parts of the body not usually associated with clots, including the splanchnic veins that drain the liver, spleen and bowel.

The rare VITT clots have been seen almost exclusively after the first dose of a viral vector vaccine, but Pai noted one case was reported following a second dose in the United Kingdom. That person did not experience a clot after their first dose.

“What that tells me is that it’s possible (to see VITT after the second dose), but it’s very likely that it’s even rarer (than after the first dose),” she said.

WHAT DO YOU DO IF YOU THINK YOU HAVE VITT?

Pai said people should seek medical care if symptoms emerge. A primary care physician — a family doctor, walk-in clinic or telehealth practitioner — can offer guidance “if symptoms are manageable.”

But if they appear more severe, head to an emergency room.

Hill said that like many other conditions, VITT appears to be easier to treat when caught early.

HOW IS IT DIAGNOSED?

A doctor would order a complete blood count (CBC) to determine whether a patient’s platelets are low, followed by additional blood tests or imaging — an MRI, for example — to detect whether or not a clot has formed.

HOW IS IT TREATED?

Effective treatments are available, Pai said, “if started in a timely fashion,” including special types of blood thinners and drugs that modulate the immune system.

She stressed that while rare, the clotting disorder has been serious and treatment may be intensive for some.

“It’s not like you get a shot of something and go home,” she said. “Generally it will involve hospitalization and some really thoughtful care by a number of different doctors.”

Hill said doctors are staying away from using the blood-thinner heparin on VITT cases, which seem to closely resemble another disorder called HIT, or heparin-induced thrombocytopenia.

Weitz said in some cases where platelets have been exceptionally low, steroids have been used.

While the mortality rate among the rare VITT cases worldwide seems to be around 20 per cent, Weitz said that number is expected to decrease.

“We’re getting better at knowing what it is and how to treat it, diagnosing it earlier,” he said. “But it’s still not something you want to get.”

Melissa Couto Zuber, The Canadian Press

Coronavirusvaccines

Just Posted

(Submitted Photo)
Skeena Voices| Dance, discipline and determination

When Braya Kluss is not dancing, she is a regular 16-year-old teenager… Continue reading

Karl Meyer was an active member of the Thornhill Volunteer Fire Department. (Terrace Professional Firefighters/ Facebook)
VIDEO: First responders parade through town in honour of fallen Thornhill firefighter

Thornhill Volunteer Fire Department’s Karl Meyer was found deceased during June 3 flooding

Suspected methamphetamine and scale seized by police. (Terrace RCMP photo)
Terrace RCMP seize guns, ammo, suspected narcotics

Man released after court appearance

Caledonia Secondary School is the recipient of a $50,000 grant to replace its aging science equipment. (File photo)
Cal snags major grant to modernize science equipment

The $50,000 comes from a pharmaceutical company

Unemployment rate drops in northwestern B.C.

Large improvement since Spring 2020

Canadian Prime Minister Justin Trudeau participates in a plenary session at the G7 Summit in Carbis Bay, England on Friday June 11, 2021. THE CANADIAN PRESS/Adrian Wyld
Canada donating 13M surplus COVID-19 vaccine doses to poor countries

Trudeau says the government will pay for 87 million shots to be distributed to poor countries

Montreal Canadiens goaltender Carey Price (31) is scored on by Vegas Golden Knights defenseman Alec Martinez, not pictured, during the second period in Game 1 of an NHL hockey Stanley Cup semifinal playoff series Monday, June 14, 2021, in Las Vegas. (AP Photo/John Locher)
Habs fall 4-1 to Vegas Golden Knights in Game 1 of NHL semifinal series

Match was Montreal’s first game outside of Canada in 2021

Kelowna-Lake Country MLA Norm Letnick, assistant deputy speaker at the B.C. legislature, presides over committee discussions. The legislature is completing its delayed spring session this week, with most MLAs participating by video conference. (Hansard TV)
B.C.’s daily COVID-19 infections dip below 100 over weekend

Only 68 new cases recorded Monday, four additional deaths

The BC Ferries website went down for a short while Monday morning following a provincial announcement that recreational travel between health authorities can resume Tuesday. (Black Press Media file photo)
BC Ferries’ website crashes in wake of provincial reopening announcement

Website back up now, recreational travel between health regions to resume as of Tuesday

The Kamloops Indian Residential School is photographed using a drone in Kamloops, B.C., Monday, June, 14, 2021. The remains of 215 children were discovered buried near the former school earlier this month. THE CANADIAN PRESS/Jonathan Hayward
Communities grapple with what to do with former residential and day schools

Some tear them down as a tool to help healing, others repurpose them as tools for moving forward

FILE – Provincial health officer Dr. Bonnie Henry talks about B.C.’s plan to restart the province during a press conference at Legislature in Victoria, Tuesday, May 25, 2021. THE CANADIAN PRESS/Chad Hipolito
B.C. watching U.K.’s COVID struggles but don’t think province will see similar pitfalls

Studies show that one dose of vaccine is only 33 per cent effective in preventing B.1.617.2 spread

RCMP Const. Shelby Patton is shown in this undated handout photo. RCMP say that Patton was hit by an allegedly stolen truck that he had pulled over on Saturday morning in Wolseley, east of Regina. THE CANADIAN PRESS/HO, RCMP
Pair charged in Saskatchewan Mountie’s death make first court appearance

Const. Shelby Patton was hit by an allegedly stolen truck that he had pulled over Saturday morning

David and Collet Stephan leave for a break during an appeal hearing in Calgary on Thursday, March 9, 2017. THE CANADIAN PRESS/Todd Korol
Appeal Court rejects stay for Alberta couple facing third trial in son’s death

Pair accused in their earlier trials of not seeking medical attention for their son sooner

Highway notices like this come down effective June 14. Public health restrictions on non-essential travel and commercial operation have hit local businesses in every corner of B.C. (B.C. government)
Province-wide travel back on in B.C.’s COVID-19 restart plan

Gathering changes include up to 50 people for outdoor events

Most Read