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have been 484,000 doses of the AstraZeneca vaccine administered in Canada – although that figure is about 10 days out of date – but that Canada is looking at international data, including from the U.K. to determine the risks of the vaccine.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

The organizers of the annual 39 days of July festival hope to return to live shows in Charles Hoey Park this year, like in this photo taken in 2019, but audiences at the show may be limited to 50 people due to health protocols. (File photo)
39 Days of July hoping for outdoor events in Duncan this summer

Annual music festival will run from June 25 to Aug. 2 this year

Cowichan Valley WildSafeBC coordinator Amanda Crowston teaches a Grade 5/6 class at Ecole Cobble Hill last fall. (Submitted)
The bears are back in town and so is WildSafeBC

The bears are back in town so keep an eye out, reminds… Continue reading

The Regional District of Nanaimo has its sights set on busing to the Cowichan Valley in time for March 2022. (News Bulletin file)
Bus link between Nanaimo and the Cowichan Valley expected by next March

Unallocated transit hours already in Regional District of Nanaimo budget

North Cowichan has heated exchange over timelines of its official community plan review. (File photo)
North Cowichan’s OCP review divides council

Tight timelines leads to heated debate

Matt Ellison was a star with the Kerry Park Islanders before embarking on a pro career that included stops in the NHL and KHL. (Submitted)
Ex-NHLers to highlight Kerry Park-Peninsula alumni games

Matt Ellison and Kyle Greentree commit to suit up in August

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

David and Julie Kaplan with their children Estelle and Justin. (Special to The News)
COVID-19 border closure stops B.C. family’s cross-country move

Maple Ridge couple, two kids, turned away at New Brunswick border

Kelowna RCMP precinct. (Michael Rodriguez - Capital News)
Kelowna RCMP reviewing rough arrest after video shared on social media

The video shows an officer punching a man while arresting him for allegedly driving a stolen car

B.C. Labour Minister Harry Bains in the B.C. legislature, May 13, 2019. (Hansard TV)
B.C. to provide three days of sick pay for COVID-19 absences

Province will support employers on cost, labour minister says

(Pixabay)
B.C. doctors could face consequences for spreading COVID misinformation: college

College says doctors have a higher level of responsibility to not spread incorrect information

The seasonal Search and Rescue program will run between May to September. ( File photo/Canadian Coast Guard)
North Vancouver Island Coast Guard Inshore Rescue Program ready to relaunch

Teams have protocols in place to ensure COVID-19 safety while providing marine safety net

Kelowna resident Sally Wallick helped rescue a kayaker in distress a week and a half ago. (Sally Wallick/Contributed)
VIDEO: Kelowna woman rescues capsized kayaker in Okanagan Lake

Sally Wallick is asking people to be prepared for the cold water and unpredictable winds

Dr. Bonnie Henry talks about phase two in B.C.’s COVID-19 immunization plan. THE CANADIAN PRESS/Chad Hipolito
All of B.C. will eventually ease out of COVID-19 restrictions at same time: Henry

People who have received two doses of a vaccine can’t yet return to post-pandemic activities with each other, she says

Winnipeg Jets’ Andrew Copp (9) and Edmonton Oilers goaltender Mike Smith (41) watch an incoming shot during second period NHL action in Winnipeg, Monday, April 26, 2021. THE CANADIAN PRESS/Fred Greenslade
‘Very jealous’: Canadian teams can’t take advantage of NHL’s relaxed COVID-19 rules

League eased some tight COVID-19 health and safety protocols over the weekend for fully vaccinated clubs

Most Read