A first shot of AstraZeneca vaccine can be followed by Moderna or Pfizer: NACI

THE National Advisory Committee on Immunization (NACI) has recommended that a first shot of the AstraZeneca vaccine can be followed by Moderna or Pfizer.

Dr. Theresa Tam, Chief Public Health Officer of Canada, said on Tuesday that NACI’s latest guidance considered a range of factors from safety concerns through vaccine supply to provide recommendations on the safety and effectiveness of the interchangeability of authorized COVID-19 vaccines or ‘mixed vaccine schedules’ for first and second doses of COVID-19 vaccines.

This advice provides provinces and territories with safe and effective options to manage their vaccine programs, specifically advising that:

* People who received a first dose of the AstraZeneca/COVISHIELD vaccine may receive either AstraZeneca/COVISHIELD vaccine or an mRNA, Pfizer-BioNTech or Moderna, vaccine for their second dose, unless contraindicated.
* People who received a first dose of an mRNA, Pfizer-BioNTech or Moderna, vaccine should be offered the same mRNA vaccine for their second dose, but if the same mRNA vaccine is not readily available or unknown, another mRNA vaccine can be considered interchangeable and should be offered to complete the vaccine series.
Tam said: “In short, the interchangeability of vaccines means you can receive one vaccine product for your first dose and safely receive a different vaccine for your second dose to complete your two-dose vaccine series for optimal protection from COVID-19.”

She added: “While NACI continues to recommend that jurisdictions maximize the number of individuals benefiting from the first dose of a COVID-19 vaccine by extending the interval between doses up to four months, in the context of increasing COVID-19 vaccine supply in Canada, the Committee recommended last week that second doses be offered as soon as possible. NACI recommends that priority for second doses should be given to those at highest risk of severe illness and death from COVID-19 disease after – or at the same time as – first doses are offered to all remaining eligible populations. NACI continues to closely monitor the effectiveness of extending dose intervals and will update recommendations as needed.”