Ontario to pause giving AstraZeneca as 1st dose COVID-19 vaccine over blood clot concerns

Ontario health officials have announced they will be no longer administering the AstraZeneca COVID-19 vaccine as a first dose option, due to increased concerns of the vaccine’s link to blood clots.

Over the last few days, there have been increased rates of vaccine-induced thrombotic thrombocytopenia (VITT) from 0.9 per 100,000 doses to 1.7 per 100,000 doses. That means about 1 in 60,000 people could be affected by the rare, but at times deadly, side effect.

As of May 8, Ontario has seen eight cases of VITT. There have been approximately 850,000 AstraZeneca doses administered in the province.

Health officials are currently reviewing the use of the vaccine for second doses and will provide guidance to those waiting for second doses of AstraZeneca in the next few weeks.

The vaccine is currently only available at pharmacies for adults aged 40 and over.

Health officials say their decision was also influenced by the high and reliable supply of Pfizer and Moderna vaccines.

Medical Officer of Health Dr. David Williams says they have been reviewing data out of the U.K. that shows the risk of blood clots is much lower when AstraZeneca is used as second dose.

Mixing doses of the COVID-19 vaccine is also being studied.

“We maintain that those who received their first dose with the AstraZeneca vaccine did absolutely the right thing to prevent illness and to protect their families, loved ones and communities,” he said.

Health policy expert for McMaster University Dr. Firas Khalid said he was not surprised by the province’s announcement and believes they are just trying to “err on the side of caution.”

“Right now with an abundance of the other types of vaccines, I think it makes sense why [Ontario] has decided right now to pause the vaccine,” said Dr. Khalid.

He said it’s important for those who have taken the first does of AstraZeneca to contact their health care provider to receive guidance on the best way forward for them.

Dr. Khalid said he believes this could be the end of the distribution of AstraZeneca.

“I don’t suspect that they will resume the rollout of them. I think if we continue getting the supply of Pfizer and Moderna, as expected. I think that it will be the end of AstraZeneca for the time being,” said Dr. Khalid.

He added his concerns is there will be a spillover effect of vaccine hesitancy towards the Pfizer and Moderna vaccines. Dr. Khalid said one of the factors that contributes to vaccine hesitancy is misinformation or lack of answers to their questions so the government should be focused on communicating to the public that the vaccines currently available in Canada are all safe.

“So our job, whether it’s a health policy experts, or whether it’s the government is to really supply the best available evidence to people, and let individuals make their best informed decision. At the end of the day, the choice of what vaccine you want to take is upon the person themselves.”

Of the more than two million people vaccinated with AstraZeneca in Canada, 12 have been were diagnosed with vaccine-induced thrombotic thrombocytopenia (VITT), and three of them died.

Alberta became the first province to pause administering AstraZeneca as a first dose vaccine because there weren’t any confirmed new shipments of the vaccine.

Fewer than 200,000 doses remain of the 2.3 million already shipped, and only 1.65 million more are expected before the end of June.

With files from The Canadian Press