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have been 484,000 doses of the AstraZeneca vaccine administered in Canada – although that figure is about 10 days out of date – but that Canada is looking at international data, including from the U.K. to determine the risks of the vaccine.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

Just Posted

Work on the first section of the Lake to Lake bike route is getting underway with these steel barriers along Martin Street. (Contributed)
Construstion gets underway on Penticton’s lake-to-lake bike route

Residents and drivers in the area should expect to see crews at work starting May 14

Vaccinations taking place. File photo
Interior Health officials urge COVID-19 vaccine registration as eligibility opens up

Over 365,000 vaccine doeses have been administered throughout the Interior Health region

Traffic is backed up along Naramata Road after a semi-truck collided with a power pole on Fleet Road. (Jesse Day - Western News)
UPDATE: Expect long delays on Naramata Road

A semi-truck collided with a power pole and downed several lines

New Border Bruins owner Dr. Mark Szynkaruk reps team colours with his young sons and wife Tracey. Photo courtesy of the Grand Forks Border Bruins
KIJHL’s Border Bruins sold to Grand Forks doctor

The league announced the sale Friday, May 14

Vikki and Don Holmberg with their three children Marshall, Ava and oldest Lexi who now lives on her own. The Penticton family is facing the prospect of homelessness after their rental home was sold, leading them to ask the community for help. (Contributed)
‘There’s just nothing’: housing crunch puts Penticton family on the brink of homelessness

Housing crisis something many in the city can likely relate to, says mother of three

Daily confirmed COVID-19 cases reported to B.C. public health, seven-day rolling average in white, to May 12, 2021. (B.C. Centre for Disease Control)
B.C. preparing ‘Restart 2.0’ from COVID-19 as June approaches

Daily infections fall below 500 Friday, down to 387 in hospital

A wildfire southeast of Vernon has been added to the BC Wildfire dashboard Friday, May 14, 2021. (BC Wildfire Service)
Wildfire sparks southeast of Vernon

The fire appears to be in a remote area east of Aberdeen Lake

Bradley Priestap in an undated photo provided to the media some time in 2012 by the London Police Service.
Serial sex-offender acquitted of duct tape possession in B.C. provincial court

Ontario sex offender on long-term supervision order was found with one of many ‘rape kit’ items

Rich Coleman, who was responsible for the gaming file off and on from 2001 to 2013, was recalled after his initial testimony to the Cullen Commission last month. (Screenshot)
Coleman questioned over $460K transaction at River Rock during B.C. casinos inquiry

The longtime former Langley MLA was asked about 2011 interview on BC Almanac program

Enderby’s Small Axe Roadhouse was the subject of nasty backlash after installing two busty beer towers. (Facebook)
Enderby bar’s busty beer taps to stay put despite backlash

‘Many folks have mansplained to us that we are sexist, misogynistic…’

Steven Shearer, <em>Untitled. </em>(Dennis Ha/Courtesy of Steven Shearer)
Vancouver photographer’s billboards taken down after complaints about being ‘disturbing’

‘Context is everything’ when it comes to understanding these images, says visual art professor Catherine Heard

Trina Hunt's remains were found in the Hope area on March 29. Her family is asking the public to think back to the weekend prior to when she went missing. (Photo courtesy of IHIT.)
Cousin of missing woman found in Hope says she won’t have closure until death is solved

Trina Hunt’s family urges Hope residents to check dashcam, photos to help find her killer

Chief Public Health Officer Theresa Tam listens to a question during a news conference, in Ottawa. THE CANADIAN PRESS/Adrian Wyld
Restrictions will lift once 75% of Canadians get 1 shot and 20% are fully immunized, feds say

Federal health officials are laying out their vision of what life could look like after most Canadians are vaccinated against COVID-19

Police are at Ecole Mount Prevost Elementary but the students have been evacuated. (Kevin Rothbauer/Citizen)
Gardener finds buried explosives, sparking evacuation of Cowichan school

Students removed from school in an ‘abundance of caution’

Most Read