FILE – A vial of the Moderna COVID-19 vaccine is displayed on Jan. 5, in Salt Lake City, Utah. (Rick Bowmer/AP)

FILE – A vial of the Moderna COVID-19 vaccine is displayed on Jan. 5, in Salt Lake City, Utah. (Rick Bowmer/AP)

Can you mix and match COVID vaccines? New Canadian study seeks to find out

Results could have implications for people who got AstraZeneca as first dose

With four approved COVID-19 vaccines in Canada, a new study launching Thursday (May 20) is looking at whether or not mixing and matching COVID vaccines is safe and effective.

The federal government is funding the study, thought the COVID-19 Immunity Task Force and the Vaccine Surveillance Reference Group, to the tune of $4.8 million. Researchers want to enrol 1,300 people to see whether or not vaccines such as Pfizer, Moderna and AstraZeneca can be mixed and matched and still be both safe and effective. Johnson & Johnson, the fourth approved vaccine, won’t be used because it’s a one-shot schedule.

The project could be especially important for people who received their first dose of AstraZeneca, which has since been pulled from use in multiple provinces, including in B.C. where the provincial health officer alluded to people having a choice of which vaccine to get for their second dose.

But the study’s co-principal investigator said that this will also let researchers to test different length intervals up to 16 weeks.

“So the four-week interval that was used in most of the clinical trials for these vaccines, and then the 16 week interval that’s being used, or that’s the upper limit of what’s being used in Canada, and then not only the initial immune response and the initial safety, but then how long that immunity lasts long term,” said Dr. Manish Sadarangani, an associate professor in the department of pediatrics at the University of British Columbia and director at the Vaccine Evaluation Center at BC Children’s Hospital.

Sadarangani said that this will be the first Canadians study of its kind and will build on studies done internationally, including in the U.K. and in Spain, about mixing and matching vaccines. However, the Canadian study will be unique because it can use the 16-week interval, which is not approved in many other countries.

“Because people can’t choose which group they’re in you, you don’t get the biases that you might get from other studies where people have chosen or have been selected to have different intervals,” he said.

“We’re looking at 13 different combinations.”

The 13 combinations will include getting Moderna first and Pfizer second, or vice versa, both with short and long intervals between doses. Others in the clinical trial will get the AstraZeneca vaccine first and then either get that again for the second dose or one of the two mRNA vaccines.

Sadarangani said there is no placebo group planned for this clinical trial sot that no matter what, everyone who participates will get a second vaccine within 16 weeks. While participants will not initially know which vaccines they are getting, Sadarangani said they can find out once the trial ends.

For more information or to participate in the trial, visit: cirnetwork.ca/mosaic. British Columbians who participate will have to be able to travel to Vancouver.

READ MORE: B.C. officials urge everyone, even those with 1st dose, to register for COVID vaccine

READ MORE: Pregnant or breastfeeding and got the COVID vaccine? B.C. researchers launch registry


@katslepian

katya.slepian@bpdigital.ca

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