'This is the best plan': Manitoba to delay 2nd dose of vaccines to reach more people faster

Manitoba's vaccine task force has decided to begin lengthening the time between first and second doses of the COVID-19 vaccine.

Data suggests 1 dose offers high degree of protection, lessens risk of severe outcomes

AstraZeneca's vaccine doesn't have to be stored at the exceptionally low temperatures required for the Pfizer-BioNTech and Moderna vaccines, which means it can be offered in a wider range of settings, such as doctors' offices and pharmacies. (Michael Bell/The Canadian Press)

Manitoba's vaccine task force has decided to begin lengthening the time between first and second doses of the COVID-19 vaccine to offer protection to more people faster.

Dr. Joss Reimer, head of Manitoba's vaccine task force, said the latest real world evidence suggests spacing out the doses by up to four months still offers high levels of protection.

"All Manitobans will be reached much quicker," she said. "Based on the information available to us, this is the best plan."

Pfizer-BioNTech and Moderna vaccine recommendations advise administering two doses of the mRNA-based vaccines spread apart by three and four weeks, respectively.

B.C.'s top doctor announced plans on Monday to spread out doses by up to four months in that province. Canada's chief science advisor panned the move, calling it a "population-level experiment" not supported by clinical data, but B.C.'s top doctor said the latest real-world data suggests a single dose is 90 per cent effective.

Reimer said the plan in Manitoba is to follow guidance from the National Advisory Committee on Immunizations (NACI). 

Hours after Reimer's Wednesday press conference, NACI released a statement saying that in the context of a limited vaccine supply, it now recommends that jurisdictions extend the interval between doses to four months.

"While studies have not yet collected four months of data on vaccine effectiveness after the first dose, the first two months of real world effectiveness are showing sustained high levels of protection," the advisory committee said in a statement.

"Extending the interval between doses was shown to be a good strategy through modelling, even in scenarios considering a six-month interval and in theoretical scenarios where waning protection was considered," NACI said.

"This will not only achieve protection of the adult population, but will also contribute to health equity."

Data out of the U.K. and Israel suggests a single dose of the mRNA-based vaccines could be 70 to 80 per cent effective in preventing infection, she said. Hospitalizations and deaths also significantly declined in those places after one dose.

WATCH | Manitoba to space out COVID-19 dosing:

Dr. Joss Reimer says Manitoba will extend the time period between first and second doses of COVID-19 vaccines

CBC News Manitoba

2 months ago
Dr. Joss Reimer, head of Manitoba's vaccine task force, said Wednesday the province will change the spacing between COVID-19 vaccinations in response to the latest real world evidence. 1:53

"That's excellent real world vaccine effectiveness," Reimer said.

"Really, across the board, we are seeing very similar results showing that the first dose is protective.… We feel very comfortable with the data we have in front of us."

AstraZeneca coming mid-March

Reimer also released more information about the AstraZeneca-Oxford vaccine. 

Health Canada approved the vaccine late last week for all age groups, and doses will soon be distributed across the country. Manitoba expects to receive a batch by the middle of the month, said Reimer.

The vaccine doesn't have the same extreme-cold storage requirements as the Pfizer-BioNTech and Moderna vaccines, making it suitable for distribution to doctor's offices and pharmacies. 

Having a third vaccine will accelerate Manitoba's vaccination campaign timelines. Reimer said last week that could mean vaccinating all eligible populations by the end of August.

Importance of 2nd dose

More than 80,000 doses of the two previously approved vaccines have been administered in Manitoba so far, including 30,000 second doses. About 2.7 per cent of Manitobans 18 and older have been fully immunized.

Clinical trials for the Moderna and Pfizer-BioNTech vaccines suggested after two doses, both were about 95 per cent effective.

It isn't clear how effective the current vaccines are against coronavirus variants that are considered more contagious and potentially more deadly.

Variants of concern first detected in the U.K. and South Africa have both been found recently in Manitoba.

Reimer said the most up-to-date data on delayed dosing, which is limited, suggests a single shot offers protection for at least two months. If subsequent studies come out and show a drop in immunity after that, Manitoba could revise its plans.

She urged Manitobans who receive one dose not to get complacent. The second dose remains important for lasting immunity.

"We don't want to have to do this next year," Reimer said.

WATCH | Reimer talks about biggest risk to Manitoba's vaccine rollout:

Dr. Joss Reimer on what she sees as the 'biggest risk' to Manitoba's vaccine rollout

CBC News Manitoba

2 months ago
Dr. Joss Reimer, head of Manitoba's vaccine task force, was asked Wednesday what she saw as the greatest risk to Manitoba's COVID-19 vaccine campaign. She said the risk is in communication, and the need to get vaccine messaging out to the public. 1:09


Bryce Hoye


Bryce Hoye is an award-winning journalist and science writer with a background in wildlife biology and interests in courts, climate, health and more. He recently finished up a stint as a producer for CBC's Quirks & Quarks. He is the Prairie rep for OutCBC. Story idea? Email

With files from Cameron MacLean and John Paul Tasker


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