The province has been encouraging Albertans to get the AstraZeneca vaccine but, at this point, there is no timeline for when the next shipment will arrive and that is raising questions of what the plan is for second doses.
Doses of AstraZeneca are being spaced out 12 weeks apart; the first doses of AstraZeneca in Alberta were administered in mid-March so second doses are expected to start mid-June.
The next batch of AstraZeneca is not expected until the end of June, and Alberta Health said Alberta has not been informed of any additional shipments.
When asked what the contingency plan is for ensuring Albertans receive their second doses on time, Alberta Health said it is monitoring emerging evidence on second doses and multiple vaccines.
“Currently, AstraZeneca second doses are being administered no later than four months and no sooner than three months after the first dose, so the second doses will not start until mid- to late-June,” said spokesperson Tom McMillan.
Global News asked whether the province should have held back doses as it did not know when the next shipment was going to arrive.
“We are prioritizing giving protection to as many Albertans as possible right now. With cases rising sharply, holding back second doses would have left tens of thousands of doses sitting in fridges for months during the third wave,” McMillan said.
Dr. Ilan Schwartz, an infectious disease professor at the University of Alberta, said one option is to delay the second dose even further, pointing to how the province moved from following manufacturer guidelines to spacing doses out up to 16 weeks.
“I don’t think, from an immunologic perspective, it’s necessarily a bad thing,” he said.
“The main thing is being able to get people fully vaccinated as early as possible in order to limit the risk of them becoming sick while partially immunized in the meantime.”
Dr. Chris Mody, the head of the Department of Microbiology, Immunology and Infectious Diseases at the University of Calgary, said an alternative strategy is potentially mixing and matching vaccines.
A clinical trial looking at mixing and matching is currently underway in the U.K. There is no clinical data to support this method and it has not been approved by Alberta Health.
Mody said the AstraZeneca, Pfizer and Moderna vaccines all target the same antigen and there is a prediction there would be a booster response from one manufacturer to the other.
“It wouldn’t be what we prefer it to do but it might well – if we’re force to do that – it…likely would be effective from an immunological perspective,” he said.
“Hopefully if we ever do get into that situation in Alberta, that information will be available at that time. We’ll be able to make a much better informed decision based on real patient data rather than on theoretical immunology.”
Schwartz stresses that there is a lot that is unknown about mixing and matching of vaccines.
“As for whether individuals will be able to complete their planned two-dose schedule with a different, totally different platform of vaccine delivery, we don’t know. We don’t have any data to support that whatsoever,” he said.