(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there have been 484,000 doses of the AstraZeneca vaccine administered in Canada – although that figure is about 10 days out of date – but that Canada is looking at international data, including from the U.K. to determine the risks of the vaccine.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 Nexii roof panel is lifted during construction of a Starbucks in Abbotsford. Alexzi Building Solutions will be building a manufacturing plant in Langford or North Cowichan to produce the sustainable construction panels. (Photo courtesy of Alexzi Building Solutions)
Langford eyed for facility to make green building alternative to concrete

Langford, North Cowichan possible sites for plant to create sustainable construction panels

Local MP Elizabeth May says the public has a right to know the identity of the company that plans to operate the massive warehouse proposed for Sidney on airport lands but residents who want to stop the project would probably have to go through the courts. (Black Press Media File)
MP Elizabeth May says public has right to know identity of Sidney warehouse operator

Residents wanting to stop the project would probably have to go through the courts, said May

Bukwila by Art Thompson, set at the steps of Lansdowne campus’ Wilna Thomas Cultural Centre, has been welcoming students to campus since 1997. (Photo courtesy of Camosun College)
World-renowned artist’s legacy lives on at Camosun College

Art Thompson made untold contributions toward Indigenous education, art and advocacy

Did you know, according to the CRD, every person produces an average of 185–200 litres of wastewater per day? Here’s where most of it gets treated, at the new wastewater treatment facility at McLoughlin Point in Esquimalt. (CRD image)
View Royal signs on to wastewater funding plan

Capital Regional District requesting to borrow up to $34.3 million to upgrade infrastructure

(The Canadian Press)
Trudeau won’t say whether Canada supports patent waiver for COVID-19 vaccines

‘Canada is at the table to help find a solution’

A map showing where the most number of cases were recorded from April 23 to 29. This map, revealing a breakdown of infections by neighborhood, was pulled from a data package leaked to the Vancouver Sun last week (and independently verified).
36 Abbotsford schools flagged for COVID-19 exposures in the last 2 weeks, shattering record

Clearbrook Elementary recorded an ‘exposure’ on all 11 school days

Island Health has confirmed COVID-19 exposures at Ecole des Deux Mondes in Campbell River on May 4 and 5, and at Mill Bay Nature School in Mill Bay on April 28, 29, 30 and May 3. (Metro Creative photo)
Two new COVID-19 school exposures confirmed by Island Health

Health authority contacting anyone exposed at Ecole des Deux Mondes, Mill Bay Nature School

Canada’s chief public health officer is reminding Canadians even those who are fully vaccinated are not immune from transmitting the COVID-19. THE CANADIAN PRESS/Adrian Wyld
Canada’s top doctor warns full vaccination does not equal full protection from COVID-19

Post-inoculation, Theresa Tam says the risk of asymptomatic infection and transmission is far lower but not obsolete

The dash cam footage, taken May 7 at 8:18 a.m. belonged to the driver of a southbound vehicle that recently travelled out of the tunnel. (Reddit/Screen grab)
VIDEO: Dash cam captures dramatic rollover crash on Highway 99

Only one person sustained injuries from the collision, says B.C. Ambulance Services

Chevy stranded on a ledge above a rocky canyon at Mimi Falls near Logan Lake, April 28, 2021. (Photo credit: Margot Wikjord)
Police officer and fire chief team up in risky rescue of stranded dog near Logan Lake

Chevy, a rescue dog, needed rescuing again after getting stuck on a ledge above rocky canyon

Police were on the scene of a fatal shooting in Abbotsford. (Black Press Media files)
B.C. government to give more than $8 million for programs to curb gang violence

221 not-for-profit projects led by local governments and school districts among others will receive a one-time grant

Gord Judson steers his log truck down a forest service road, using two-way radio and call signals to mark his position for oncoming traffic. (B.C. Forest Safety Council)
Planning some B.C. wilderness fishing? Don’t catch a log truck

Remote recreation areas bracing for heavy pandemic pressure

Most Read