Alberta stops offering first doses of AstraZeneca COVID-19 vaccine due to supply issues

Alberta Health says the province has stopped administering first doses of the AstraZeneca-Oxford COVID-19 vaccine in favour of other brandsbecause supply of the vaccine is expected to become scarce.

Alberta's existing supply of AstraZeneca will be used as second doses, the provincial health department confirmed on Tuesday.

Dr. Deena Hinshaw, Alberta's chief medical officer of health, said it's unclear when Alberta will get additional shipments of AstraZeneca, and that lack of supply prompted provincial health officials to alter theimmunization strategy.

The remaining supply ofAstraZeneca will also be reserved for people who have a medical condition thatmakes them ineligible for messenger RNA vaccines, also known asmRNA vaccines, which are produced by Pfizer-BioNTech and Moderna.

"Based on global supply challenges, we do not know when we will get additional supply,"Hinshawsaid in a statement on Twitter.

"That's why we are making the prudent move saving the remaining 8,000 doses for those who have a contraindication to an mRNA vaccine, or for second doses."

Mix and match?

It's unclear whether those who receivedAstraZeneca can be offered a different vaccine for their second dose, but Hinshaw says health officials are reviewingthe research.

• Canadian officials watching the data on alternating COVID-19 vaccines

A study of a "mismatched" vaccine regimen is underway in the U.K.

"Some people have asked if they will receive an mRNA vaccine for their second dose instead of AstraZeneca," Hinshawwrote Tuesday.

"We are reviewing emerging evidence in the U.K. and other places as we speak to decide the best path forward.

"I want to reassure Albertans that AstraZeneca is a good vaccine that will protect you against severe outcomes. This decision reflects us adapting to the supply and the emerging evidence, which we will keep on doing."

More than 250K doses administered

Alberta has administered roughly255,000 first doses of AstraZeneca and 2,200 second doses, Alberta Health said in a statement to CBC News on Tuesday.

The remaining supply accounts for about 8,400 doses, the statement said.

Alberta Health said itcontinues to receive shipments of thePfizer-BioNTechand Moderna vaccines in large and consistent shipments. More than 236,000 doses are arriving this week alone.

Alberta Health said therewere no remainingbookings through Alberta Health Services for first doses but a "very small number" of bookingswith pharmacieswill go ahead as scheduled, Alberta Health said.

More than 318,841 Albertans have been fully immunized with two doses of COVID-19 vaccine. As of Sunday, about 35.7 per cent of Alberta's population had received at least one dose.

• By the numbers: Alberta expected to receive about 2.4 million more vaccine doses by July 4

Use of the AstraZeneca vaccine has been under added scrutiny in recent weeks, particularly after Canada's panel of vaccine experts recommended that people who aren't at high risk of contracting COVID-19 may want to wait to get a dose of the Pfizer or Moderna.

The AstraZeneca vaccine has been linked to vaccine-induced immune thrombotic thrombocytopenia (VITT), an extremely rare blood clot disorder.To date, Alberta has reported twocases of VITT and one death.

The currently reported frequency of blood clots from the AstraZeneca vaccine ranges from onein 25,000 doses in Norway to one in onemillion doses in the U.K., Alberta Health said.

The federal government confirmed last week that it will continue to procure AstraZeneca, and that well over a million doses are expected to arrive between now and the end of June.