(AP Photo/Matthias Schrader, FIle)

(AP Photo/Matthias Schrader, FIle)

VIDEO: ‘Extremely, extremely rare’ blood clots ‘may be linked’ to AstraZeneca, Health Canada says

One case of the adverse effect has been reported in Canada

Health Canada said that extremely rare blood clots “may be linked” to use of the AstraZeneca vaccine.

In a statement released Wednesday (April 14), the agency said that its findings are in line with other regulatory agencies. The potentially AstraZeneca-linked blood clots are specifically called central venous sinus thrombosis (CVST) and are associated with low levels of blood platelets. The vaccine showed an effectiveness of about 62 per cent in preventing symptomatic COVID-19 two weeks following the second dose.

“As a result, the Department has updated warnings in the product information to inform Canadians of the possible side effects and to provide information about the signs and symptoms and when to seek prompt medical attention following vaccination,” the agency said.

However, “no specific risk factors” have been identified so Health Canada is not restricting the use of the vaccine for any population. Dr. Supriya Sharma, chief medical adviser at Health Canada, said that people who receive the AstraZeneca vaccine should look for the following symptoms four to 20 days post-shot: really serious persistent headaches, persistent serious abdominal pain, pain in your limbs that’s quite severe and persistent or any unusual bruising other than at the injection site.

Wednesday’s update comes the day after the Public Health Agency of Canada was alerted of the first case of blood clots in a Quebec woman who had received the AstraZeneca vaccine. She has been treated and is recovering at home.

Sharma said that her agency still believes that “the benefits of AstraZeneca vaccine outweigh the risks in all age groups” and that individuals should follow government recommendations on COVID-19 vaccines.

“Get whichever vaccine is available to you. The longer you wait to get vaccinated the longer you’re not protected,” Sharma said.

Sharma said there have been 484,000 doses of the AstraZeneca vaccine administered in Canada – although that figure is about 10 days out of date – but that Canada is looking at international data, including from the U.K. to determine the risks of the vaccine.

Health Canada has determined the rate of potentially AstraZeneca related blood clots to be four in one million based on a U.K. data set because it is “the most complete,” Sharma said, based on the number of doses doled out there and their post-vaccination program.

Overall, Sharma said the rate can vary from one in 100,000 and one in 250,000 – the latter of which is equivalent to four in one million.

Sharma said that comparisons between the AstraZeneca blood clots and those caused by other medications, such as birth control, are are to compare because they are different forms of clots.

However, Sharma said that the risks of blood clots from the following are:

  • In women ages 15 to 45: 1 in 3,300
  • Birth control pill: 1 in 1,600
  • Pregnant women: 1 in 300
  • Post-partum: 1 in 100
  • Hospitalized with COVID-19: 1 in 5

“The risks of regular clots with COVID is much, much higher than with other things we talk about in terms of benefits and risks and it’s much much much higher than having this very very severe clot,” Sharma said.

The CVST clots are “extremely, extremely rare,” she said.

“One of the hypotheses in what’s causing this is really an activation of the immune system that then leads to platelets being activated, causing clots and then because those platelets are consumed in the process, the overall count goes down,” Sharma said, noting that this is similar to what can be seen as a result of Heparin, a blood thinner medication.

“We still have Heparin on the market. We still use it in prevention, we still use it in syringes to prevent clots… it’s helpful sometimes putting in context with other types of clots, but really, the thing we’re looking at is this very, very rare chance of having this severe clot that you can diagnose and treat and potentially getting sick with COVID, getting seriously ill and potentially dying.”

The National Advisory Committee on Immunizations recommendations to not use the AstraZeneca vaccine for people under the age of 55 remains in effect.

READ MORE: PHAC receives first report of blood clot linked to AstraZeneca


@katslepian

katya.slepian@bpdigital.ca

Like us on Facebook and follow us on Twitter.

Want to support local journalism during the pandemic? Make a donation here.

Coronavirusvaccines

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

A health-care worker prepares a dose of the Pfizer-BioNTech COVID-19 vaccine at a COVID-19 vaccine clinic in Toronto on Thursday, January 7, 2021. THE CANADIAN PRESS/Nathan Denette
65 new cases of COVID-19 in Interior Health

Overall, B.C. is seeing a decrease in COVID-19 cases

FILE - In this April 19, 2021, file photo, Keidy Ventura, 17, receives her first dose of the Pfizer COVID-19 vaccine in West New York, N.J. States across the country are dramatically scaling back their COVID-19 vaccine orders as interest in the shots wanes, putting the goal of herd immunity further out of reach. (AP Photo/Seth Wenig, File)
5 more deaths, 131 new cases of COVID-19 in Interior Health over the weekend

Those 18-years and older in high-transmission neighbourhoods can register for the vaccine

District of Clearwater meetings are open to the public. The meeting agendas and past meetings minutes can be viewed on the DOC's website. Every meeting has time allocated at the end for comments from the public.
District of Clearwater hires new chief adminstrative officer

The new CAO will arrive at the end of June.

A medical worker prepares vials of the COVID-19 vaccines, Chinese Sinopharm, left, Sputnik V, center, and Pfizer at a vaccine centre, in the Usce shopping mall in Belgrade, Serbia, Thursday, May 6, 2021. Serbian authorities are looking for incentives for people to boost vaccination that has slowed down in recent weeks amid widespread anti-vaccination and conspiracy theories in the Balkan nation. The government has also promised a payment of around 25 euros to everyone who gets vaccinated by the end of May. (AP Photo/Darko Vojinovic)
38 new COVID-19 cases, more than 335k vaccines administered in Interior Health

Interior Health also to start targeted vaccinations in high transmission neighbourhoods

FILE PHOTO
Second doses of COVID-19 vaccine will be available, as AstraZeneca supply runs low: Interior Health

Province expecting large volumes of Pfizer BioNTech as age-based cohort immunization program ramps up

A bullet hole is seen in the windshield of an RCMP vehicle approximately 4 km from Vancouver International Airport after a one person was killed during a shooting outside the international departures terminal at the airport, in Richmond, B.C., Sunday, May 9, 2021. THE CANADIAN PRESS/Darryl Dyck
Homicide team IDs man in fatal YVR shooting as police grapple with spate of gang violence

Man, 20, charged in separate fatal shooting Burnaby over the weekend

Keith MacIntyre - BC Libertarian
Penticton’s Keith MacIntyre new leader of the B.C. Libertarian Party

The Penticton businessman was voted in by members of the party on May 8

RCMP are searching for Philip Toner, who is a 'person of interest' in the investigation of a suspicious death in Kootenay National Park last week. Photo courtesy BC RCMP.
Man sought in suspicious Kootenay death found in Lake Country

Philip Toner is a person of interest in the death of Brenda Ware

Vernon North Okanagan RCMP reported to 287 mental health calls between Jan. 1, 2021, and May 1. (Black Press files)
‘It’s not the police’s responsibility to deal with mental health calls’: Vernon RCMP

RCMP remind public to take care of mental health and well-being, while better solutions are sought

Thompson Rivers University campus is in Kamloops, B.C. (KTW file photo)
Thompson Rivers the 1st B.C. university to supply free menstrual products

The university will offer the products this September

Fraser Health is using ‘targeted’ vaccination clinics in high-risk areas of the Lower Mainland. (Fraser Health photo)
B.C.’s COVID-19 decrease continues, 515 new cases Tuesday

426 seriously ill people in hospital, up from 415 Monday

The site of Sunfest, Laketown Ranch, will be open for camping this summer. (Citizen file)
Sunfest country music bash won’t be shining on B.C. in 2021

Annual Vancouver Island Festival cancelled due to COVID-19, along with Laketown Shakedown

Tla-o-qui-aht First Nation elected chief councillor Moses Martin, who was also Chantel Moore’s grandfather, speaks to media in Port Alberni on Aug. 16, 2020, during a visit from NDP leader Jagmeet Singh following the police shooting of Chantel Moore. (Elena Rardon photo)
Mother of 2 shot by police in critical condition, says B.C. First Nation chief

Community ‘devastated’ by third member of 1,150-person Vancouver Island nation shot in less than a year

B.C. Agriculture Minister Lana Popham promotes the government’s BuyBC food program in 2019. (B.C. government)
Money running out for fresh fruit, vegetables, milk in B.C. schools

‘Looking at ways to support this type of program,’ minister says

Most Read