A new Canadian study has found a link as to why some people may develop dangerous but extremely rare blood clots after receiving AstraZeneca's COVID-19 vaccine.
Researchers at McMaster University in Hamilton, Ont. have pinpointed a group of amino acids that can be "targeted" by key antibodies in the blood following the jab that can trigger an "intense clotting reaction" for some people.
However, experts stress that the odds of developing the rare blood clot known as vaccine-induced immune thrombotic thrombocytopenia (VITT) from the first dose of AstraZeneca COVID-19 vaccine are low, and even lower with the second dose.
Dr. Ishac Nazy, lead author of the study and scientific director of the McMaster Platelet Immunology Laboratory, told CTV News Channel on Wednesday that the new findings could help doctors develop quicker diagnostics and treatment for the clotting.
"What we've done is we used basic science to understand exactly how these vaccines are actually producing antibodies that lead to these aggregates in our bodies that activate platelets and lead to clots," Nazy said.
"We were able to pinpoint exactly where these antibodies are binding, and of course knowing this is super important for understanding how the disease happens," he added.
The findings were published Wednesday in peer-reviewed scientific journal Nature.
According to the study, some individuals can produce "extremely unusual" antibodies that tightly bind to a specific site on the naturally occurring platelet factor 4 (PF4) protein in the blood after receiving a COVID-19 adenoviral vector vaccine, such as AstraZeneca or Johnson & Johnson.
Researchers say the location and strength of this binding allow the antibodies to cluster PF4 proteins together and form "immune complexes" that can activate these proteins and cause clotting in various spots throughout the body.
Nazy noted that VITT is similar to a syndrome called heparin-induced thrombocytopenia (HIT), which the team of researchers has been studying for many years.
According to the study, researchers analyzed blood samples from five patients with VITT and compared them with blood samples of 10 patients with HIT and 10 samples from healthy individuals.
While the two syndromes are different, Nazy says both cause the combination of low blood platelet count and severe clotting from antibodies against the PF4 protein. He added that previously studying HIT helped the team pinpoint how the clots were occurring in AstraZeneca recipients.
Looking at the amino acids of the interaction between the VITT antibodies and PF4 protein, researchers found eight specific amino acids on PF4 that were identical to the binding site of HIT.
"Essentially, this means that VITT antibodies bind to PF4, which activates platelet and other clotting factors causing the severe clotting disorder which characterizes the syndrome," the researchers said in a press release.
However, researchers noted that the VITT antibodies bound more tightly to PF4 than the HIT antibodies.
"We do not know why these rare antibodies form in the first place, and we do not know why they cause blood clots in unusual places; but we do know the specific target of the VITT antibody," researchers said in the release.
By understanding how these reactions can be avoided, researchers said they "believe that safer vaccines can be developed."
Nazy says the team at McMaster has been in contact with both Astra Zeneca and Johnson & Johnson regarding their findings.
"Moving forward from here there will be more collaborations with them so we can actually see what our discovery has shown and how that can help inform as to what ingredients in the vaccine can lead to the development of these antibodies," Nazy said.
Nazy said determining what specifically is causing the clots is difficult, however, researchers continue to probe the matter.
"It's hard to know right now if it's a specific item in the vaccine that affects a certain specific number of people and why. Those discoveries still have to be made so that a decision can be also made at the level of the company and how they would proceed from there," Nazy said.
While Canada is no longer recommending AstraZeneca's COVID-19 vaccine as a second dose option, Nazy said it is important to continue researching the rare side effect as many other countries have continued to use the shot.
"There's only a handful of companies that are making vaccines, and we need to vaccinate the whole world so there's a lot of work to be done," he said.
Canadian pet owners are finding companionship beyond dogs and cats. Tigers, alligators, scorpions and tarantulas are among some of the exotic pets they are keeping in private homes, which pose risks to public safety and animal welfare, advocates say.
Anne Marie Cavner was the closest she'd ever been to meeting her biological father, but then life dealt her a blow. From an unexpected loss to a host of new relationships, a DNA test changed her life, and she doesn't regret a thing.
The Canadian Medical Association is asking the federal government to reconsider its proposed changes to capital gains taxation, arguing it will affect doctors' retirement savings.
The 2024 federal budget released last week includes numerous big spending promises that have garnered headlines. But, tucked into the 416-page document are also series of smaller items, such as promising to amend the law regarding infant formula and to force banks to label government rebates, that you may have missed.
Upset about high interest rates, growing paperwork and heavy regulatory burdens, protesting farmers have become a familiar sight across Quebec since December.
A veteran tabloid publisher was expected to return to the witness stand Tuesday in Donald Trump's historic hush money trial.
Prince William and his wife Kate thanked the public for their messages which had been sent to mark the sixth birthday of their youngest son Louis on Tuesday.
Quebec's Health Department says it has received 28 reports of eye damage related to the April 8 total solar eclipse that passed over southern parts of the province.
A Peruvian psychologist who suffered from an incurable disease that weakened her muscles and had her confined to her bed for several years, died by euthanasia, her lawyer said Monday, becoming the first person in the country to obtain the right to die with medical assistance.
People in Manitoba could soon be able to grow recreational cannabis in their homes.
Upset about high interest rates, growing paperwork and heavy regulatory burdens, protesting farmers have become a familiar sight across Quebec since December.
A Toronto cop who was driving to a break-and-enter call last year when he crashed into a civilian vehicle and seriously injured two people has been cleared by the province’s police watchdog, but concerns are being raised about the speed at which they were travelling on the way to the scene.
Three children and a driver were taken to hospital after a school bus and a truck collided on Route 400 in Russell, Ont.
An evacuation order was issued on Monday afternoon for homes in the area of Cold Lake First Nation.
Authorities on both sides of the Canada-U.S. border resumed search efforts Monday to find two men who went missing while kayaking off Vancouver Island over the weekend.
At least 5 people have died while crossing the English Channel, according to French media, hours after the U.K. approved the migrant deportation bill.
South Korean man has been sentenced to 14 months in prison for killing 76 cats in one of the country's most gruesome cases of animal cruelty in recent years.
An Indian national has been sentenced in the United States to five years in prison in connection with a dark web drug enterprise that stretched as far as Canada, an American Department of Justice release says.
Two Malaysian military helicopters collided midair and crashed during a training session on Tuesday, killing all 10 people on board and injuring a swimmer in a pool, authorities said.
An Arizona judge declares a mistrial Monday in the case of a rancher accused of fatally shooting a Mexican man on his property near the U.S.-Mexico border.
Swedish customs made one of the country's biggest-ever cocaine seizures after confiscating around 1.4 tons of the drug last week in a port near Stockholm, an official told Swedish television on Tuesday.
The Canadian Medical Association is asking the federal government to reconsider its proposed changes to capital gains taxation, arguing it will affect doctors' retirement savings.
The 2024 federal budget released last week includes numerous big spending promises that have garnered headlines. But, tucked into the 416-page document are also series of smaller items, such as promising to amend the law regarding infant formula and to force banks to label government rebates, that you may have missed.
NDP Leader Jagmeet Singh is raising eyebrows anew over his carbon pricing stance, refusing to say today whether or not he would keep scheduled increases in place if he becomes prime minister.
Share your story by emailing us at dotcom@bellmedia.ca with your name, general location and phone number in case we want to follow up. Your comments may be used in a CTVNews.ca story.
Whether you’re shedding pounds with the help of effective new medicines, slimming down after weight loss surgery or cutting calories and adding exercise, there will come a day when the numbers on the scale stop going down, and you hit the dreaded weight loss plateau.
The Manitoba government is funding mental health support for first responders, following the recent death of a Winnipeg firefighter.
Quebec's Health Department says it has received 28 reports of eye damage related to the April 8 total solar eclipse that passed over southern parts of the province.
For the first time in five months, NASA engineers have received decipherable data from Voyager 1 after crafting a creative solution to fix a communication problem aboard humanity’s most distant spacecraft in the cosmos.
Biologists, cognitive scientists and philosophers across the globe say there is a reasonable possibility the vast majority of creatures on Earth are sentient in some way.
Taylor Swift's latest album, 'The Tortured Poets Department,' which dropped on Friday, became the most-streamed album on its first day across Spotify, Amazon Music, and Apple Music.
Victoria Beckham, the fashion designer once known best as Posh Spice, celebrated her 50th birthday this weekend in London, where she was joined by her former Spice Girls bandmates.
North Korean animators may have helped create popular television cartoons for big Western firms, including Amazon and HBO Max, despite international sanctions on North Korea, a research report has found.
Federal Labour Minister Seamus O'Regan says he has appointed an Industrial Inquiry Commission to dig deeper into the underlying causes of B.C.'s port strike last summer.
The U.S. Federal Trade Commission on Monday sued to block Coach parent Tapestry's US$8.5 billion deal to buy Michael Kors owner Capri, saying it would eliminate 'direct head-to-head competition' between the flagship brands of the two luxury handbag makers.
The gap between the highest earners and lowest income groups last year was at its widest since 2015 as the wealthiest households saw income grow much faster than lower-income Canadians.
A home in B.C.'s Okanagan that features a weathering steel shell designed to provide some protection against wildfires has been listed for sale at $3.8 million.
When Kema Ward-Hopper and her then-fiance Nicholas Hopper, both from the U.S., decided to get married in Costa Rica, they had no idea that they’d end up relocating there a few years later.
If you’re looking for something to sweeten your dinner table this Passover, Jewish dietitian and chef Micah Siva has a few ideas for you.
The giant stone statues guarding the Lions Gate Bridge have been dressed in custom Vancouver Canucks jerseys as the NHL playoffs get underway.
Connor Hellebuyck made sure he did one important thing while winding down Sunday after the Winnipeg Jets beat the Colorado Avalanche 7-6 in Game 1 of their first-round playoff series. The favourite to win this season's Vezina Trophy as the NHL's top goalie made sure his recovery included replenishing his fluids.
French police evicted migrants from a makeshift camp in Paris a few steps away from the Seine River on Tuesday, the latest operation in what aid groups call a campaign of 'social cleansing' ahead of the Summer Olympics.
Ford recalled more than 55,000 trucks and SUVs over a battery detection issue, according to a Transport Canada recall notice.
Honda Canada is set to build an electric vehicle battery plant near its auto manufacturing facility in Alliston, Ont., where it also plans to produce fully electric vehicles.
Gas prices are once again on the move in B.C.’s Lower Mainland but this time in the other direction.
A local Oilers fan is hoping to see his team cut through the postseason, so he can cut his hair.
A family from Laval, Que. is looking for answers... and their father's body. He died on vacation in Cuba and authorities sent someone else's body back to Canada.
A former educational assistant is calling attention to the rising violence in Alberta's classrooms.
The federal government says its plan to increase taxes on capital gains is aimed at wealthy Canadians to achieve “tax fairness.”
At 6'8" and 350 pounds, there is nothing typical about UBC offensive lineman Giovanni Manu, who was born in Tonga and went to high school in Pitt Meadows.
Kevin the cat has been reunited with his family after enduring a harrowing three-day ordeal while lost at Toronto Pearson International Airport earlier this week.
Molly Knight, a Grade 4 student in Nova Scotia, noticed her school library did not have many books on female athletes, so she started her own book drive in hopes of changing that.
Almost 7,000 bars of pure gold were stolen from Pearson International Airport exactly one year ago during an elaborate heist, but so far only a tiny fraction of that stolen loot has been found.
When Les Robertson was walking home from the gym in North Vancouver's Lower Lonsdale neighbourhood three weeks ago, he did a double take. Standing near a burrow it had dug in a vacant lot near East 1st Street and St. Georges Avenue was a yellow-bellied marmot.
As the wildfire season ramps up and a pair of evacuation alerts are now in place, one of British Columbia’s top fire officials is making a personal appeal to the public to take some simple steps that could safeguard their homes.
The giant stone statues guarding the Lions Gate Bridge have been dressed in custom Vancouver Canucks jerseys as the NHL playoffs get underway.
Backlash to decriminalization dominated question period Monday in the B.C. legislature, with the Official Opposition BC United and BC Conservatives calling for the province to end the three-year pilot project.
A recent survey shows not all Canadians are ready to make the switch to an electric vehicle as they have concerns about charging stations, cold weather and battery life.
Auston Matthews scored the winner in the third period and added two assists as the Toronto Maple Leafs topped the Boston Bruins 3-2 on Monday to even their first-round playoff series 1-1.
Toronto’s police chief has ordered a “full internal review of all aspects of plainclothes policing” following an acquittal in the first-degree murder trial of Umar Zameer.
Monday, a judge ruled a proposed class-action lawsuit can go forward despite efforts from lawyers representing the archdiocese of Edmonton and a religious order to have it struck down.
Calgary police have released a photo of a man wanted after a deadly shooting in the community of Shawnessy last month.
The largest public hearing in the city’s history is set to get underway Monday morning.
Three children and a driver were taken to hospital after a school bus and a truck collided on Route 400 in Russell, Ont.
The Pembroke Regional Hospital says it is expecting longer wait times this spring and summer because of anticipated physician shortages.
A cold few days are in the forecast for the city of Ottawa, before spring-like temperatures return in time for the weekend.
Montreal police are investigating after four vehicles were set on fire Monday night.
Upset about high interest rates, growing paperwork and heavy regulatory burdens, protesting farmers have become a familiar sight across Quebec since December.
Quebec's Health Department says it has received 28 reports of eye damage related to the April 8 total solar eclipse that passed over southern parts of the province.
A historical hangar at the former Edmonton municipal airport beside the NAIT main campus was on fire Monday night.
An evacuation order was issued on Monday afternoon for homes in the area of Cold Lake First Nation.
The Alberta government is changing existing legislation to lower utility bills in Calgary.
A male youth is dead after an incident near the Halifax Shopping Centre on Monday.
Three people are in hospital with serious injuries after a two-vehicle crash in New Germany, N.S., on Sunday.
Pictures of a poster encouraging people to steal from Loblaw Companies Limited next month on a specific date have been circulating online.
Homeowners in a Manitoba community are cleaning up after being impacted by a natural phenomenon last week.
Marion Street Eatery is set to close its doors for good after over a decade serving up steaming plates of eggs benedict, grilled cheese and brisket hash.
People in Manitoba could soon be able to grow recreational cannabis in their homes.
Regina city councillors are set to consider lowering the speed limit in the Cathedral neighbourhood to 30 kilometres per hour on Wednesday.
Members of the Sask. Party claim a recent trip by the leader of the opposition reveals her party's secret support for the federal carbon tax.
The Saskatchewan NDP are calling for the resignation or firing of Education Minister Jeremy Cockrill, saying he lied about apologizing for comments he made to a mother whose daughter died.
Ornge Air Ambulance says one person has critical injuries after a serious crash in the area of Fischer Hallman Road and Victoria Street South in Kitchener.
A Kitchener man who forgot his laptop on a bus in January says he’s now being asked to pay $750 to get it back from whoever has the device.
Brantford police say one person remains in critical condition after a shooting in Brantford Sunday night.
A Saskatoon mortgage broker says the federal government’s move to help Muslim Canadians get into the housing market by promoting halal mortgages is not such a radical idea — it’s helping families buy their first home without breaking their faith.
A driver caught using vice grips in place of a steering wheel was ticketed Wednesday after being stopped by police on a rural road.
The Saskatchewan Rush are absent from the National Lacrosse League playoffs for a third straight season, a difficult end to an postseason push born out of a rocky start.
It was a sad scene at Tom Davies Square in Sudbury on Monday morning, where a man was being sentenced for a crash that killed a North Bay woman who was driving to her wedding shower.
Hundreds of drivers were charged in a recent three-day commercial motor vehicle blitz conducted by the Ontario Provincial Police and Ministry of Transportation.
Plans to redevelop the former St. Joseph’s Hospital on Paris Street in Sudbury are moving ahead, with the first stage of the approvals process taking place next week.
The Dutton/Dunwich Fire Department responded to the scene near mile marker 142 between Currie Road and Iona Road, after the vehicle caught fire.
Council is be urged to ensure that a plan to redevelop the Byron Gravel Pit also maintains a summer home for its long-time residents — a colony of bank swallows.
Brian Gray-Hicks likes to be active, and goes for daily walks near his home in Clinton.
Orillia council authorized a bylaw to rename Centennial Drive Lightfoot Drive at its meeting on Monday.
Repeat Offender Parole Enforcement (R.O.P.E.) Squad requesting the public's help in locating a federal offender.
A routine patrol in Midland turned up an illegal driver and several prohibited knives.
As a young man, Jim Oran's life took unexpected turns, ultimately leading him to Sweden, where he encountered a woman who would later give birth to a child he never knew existed.
A federal offender known to frequent southwestern Ontario has been arrested.
The town of Amherstburg may one day soon have a public boat launch at the K. Walter Ranta Memorial Park after agreeing to move forward with a plan, despite the multi-million dollar price-tag.
Mounties searching for a driver who struck and killed a woman on Vancouver Island last week released new details about the suspect vehicle Monday.
Authorities on both sides of the Canada-U.S. border resumed search efforts Monday to find two men who went missing while kayaking off Vancouver Island over the weekend.
The B.C. government says legislation formally recognizing the Haida Nation's Aboriginal title over Haida Gwaii was introduced in the legislature Monday.
Major crime detectives in British Columbia are investigating a suspected homicide after a body was found in a remote area southeast Kelowna over the weekend.
A banana ball python that was stolen from a Kelowna pet store on Saturday has been returned unharmed, Mounties said.
Nurses held a rally Wednesday at a hospital in the B.C. Interior that closed its emergency department more than a dozen times last year due to insufficient staff.
The City of Lethbridge is calling the first year of its curbside organics waste collection program a success.
Coaldale RCMP are looking for the public's help to locate a suspect in a hit-and-run in a McDonald's parking lot earlier this month.
An agreement to protect a sprawling ranch in southern Alberta from development is the largest of its kind in the country, the Nature Conservancy of Canada says, and will allow the family that owns it to continue raising cattle there.
Nearly a hundred people dedicated to saving the Sault Ste. Marie YMCA from closure gathered in front of the facility in a showing of support.
Hundreds of drivers were charged in a recent three-day commercial motor vehicle blitz conducted by the Ontario Provincial Police and Ministry of Transportation.
The United Chiefs and Councils of Manitoulin Anishnaabe Police announced Monday it is creating its first full-time drug enforcement unit on the island.
The Department of Fisheries and Oceans says two people were found dead and four others survived after a boat capsized off the west coast of Newfoundland.
Technology from the 19th century has been brought out of retirement at a Newfoundland gardening store, as staff look for all the help they can get to fill orders during a busy season.
A Celebrity Apex cruise to the Caribbean this month turned into a rocking Newfoundland kitchen party when hundreds of people from Canada's easternmost province happened to be booked on the same ship.
The Shopping Trends team is independent of the journalists at CTV News. We may earn a commission when you use our links to shop. Read about us.
