Archive 22: Summary of National Advisory Committee on Immunization (NACI) statement: Recommendations on the use of COVID-19 vaccines

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This is an archived version. Please refer to current COVID-19 vaccine pages:

Publication date: October 22, 2021

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NACI recommends that:

NACI has updated information on vaccine schedules:

To see the full update, please visit NACI Recommendations on the use of COVID-19 vaccines.

What you need to know

Severe immediate allergic reactions (e.g., anaphylaxis) following vaccination with authorized COVID-19 vaccines

NACI recommends that:

Optimal interval between the first and second doses of a two-dose primary COVID-19 vaccine series

To see the full update, please visit NACI Recommendations on the use of COVID-19 vaccines.


"Canada took an approach early in the pandemic to get the most benefit from the COVID-19 vaccines available by extending the intervals between doses to maximize the number of Canadians benefiting from the first vaccine dose. This was supported by principles of vaccine science and early evidence on the performance of the vaccines. Over time, we have seen new evidence from Canada and the United Kingdom that suggest the strongest immune responses and protection may be achieved when the vaccine doses are provided at least 8 weeks apart. It is important to remember that these vaccines work very well in most people, and ensuring high vaccine coverage for the primary series is one of our most important tools in the pandemic response right now."

"NACI has been carefully monitoring the evolving evidence on anaphylaxis following COVID-19 vaccines. We are very encouraged to see that second doses can be safely provided even to those who have had a severe, immediate allergic reaction after a first dose of an mRNA COVID-19. This should be done with appropriate clinical oversight, and will help many more people have the very good protection against COVID-19 that can be achieved through a complete primary vaccine series."

Dr. Shelley Deeks, NACI Chair

"It is great news that NACI’s review of the latest evidence supports that people who experienced very rare immediate severe allergic reactions after receiving a first dose of a COVID-19 vaccine can safely receive subsequent doses of COVID-19 vaccines with appropriate clinical oversight. This means these individuals can receive the additional doses they need to complete their primary COVID-19 vaccines series and be better protected against COVID-19. "

"As well, updated information from NACI on optimal intervals between first and second doses of a COVID-19 primary vaccine series shows that extending intervals beyond initially authorized intervals leads to stronger immune responses, providing better protection against COVID-19 infection and severe outcomes. These updates are further examples of Canada’s ongoing commitment to carefully monitor vaccine safety, and to update vaccine advice as evidence evolves in order to provide Canadians with the best possible protection against COVID-19."

Dr. Theresa Tam, Chief Public Health Officer

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