Your first dose was AstraZeneca. Could your second one be Pfizer?


VANCOUVER — With tens of thousands of British Columbians ages 40 and older now getting their AstraZeneca shots and no additional shipments of that vaccine scheduled, many are wondering if they’ll get their second dose within the four-month window.

“A big chunk of AstraZeneca comes from the Serum Institute in India, and the cases in India are spiralling out of control. There is huge pressure on the Indian government to manufacture AstraZeneca for Indian use,” said Mahesh Nagarajan, professor of operations and logistics at UBC’s Sauder School of Business.

“So, are we going to get adequate supplies to give everyone a second shot of AstraZeneca in a timely fashion, is a question that I don’t think I know the answer to,” he said.

B.C is expecting millions of doses of the Pfizer vaccine in the coming months. Vancouver immunologist Dr. Kelly McNagny says research out of the U.K. suggests the second vaccine could be different than the first.

“There are a lot of studies going on currently where they are doing mixing and matching, either AstraZeneca first and then Pfizer or Moderna second, and vice versa,” McNagny said. “The data is not in yet. It should be in the summer. But, all indications – and this is me speaking as an immunologist – would suggest they should work just fine mixing and matching.”

Nagarajan says that would relieve a lot of pressure on B.C. health authorities.

“If you can pool all the vaccines together, it’s going to be a lot simpler,” he said.

Having two different doses could actually be beneficial, according to McNagny.

“If you get a second one just because it’s a little different, it will activate your immune system in a more broad way,” he said. “All the immunology tells you it should work, but the government is showing an abundance of caution to see the data come in before saying it’s OK.”

Regardless of whether vaccine mixing and matching is approved, his advice is the same.

“It’s better to get any vaccine at this stage, just so you get some protection,” said McNagny.

And if you get side effects like a sore arm, headaches of fever and chills? “That’s all telling you the immune system is kicking in.”