MEDICAL ADVISORY: Updated NACI Recommendations on COVID-19 Vaccine Schedules
Issued by: M. Mustafa Hirji, MD, MPH, FRCPC, Medical Officer of Health & Commissioner (Acting)
The following is an update to the Medical Advisory issued on June 4 on Interchangeability of Authorized COVID-19 Vaccines, which highlighted that effective June 4, 2021, in Ontario, individuals may receive the same vaccine for their first and second dose or a combination of a viral vector vaccine (AstraZeneca) as their first dose and an mRNA vaccine (e.g. Moderna) as their second dose. Both will count as a completed series.
Revised NACI Recommendations
On June 17, NACI released the following recommendations:
For first doses:
- An mRNA vaccine is preferred as a first dose to start a vaccine series, unless there is a contraindication, such as an allergy to an mRNA vaccine or its components
- A viral vector vaccine may be offered to start a vaccine series when an mRNA vaccine is inaccessible or contraindicated
For second doses:
- An mRNA vaccine is now preferred as the second dose for
individuals who received a first dose of AstraZeneca, based on emerging evidence of a potentially better immune response from this mixed vaccine schedule and to mitigate the potential risk of VITT associated with viral vector vaccines
- People who received two doses of AstraZeneca vaccine can rest assured that the vaccine provides good protection against infection and very good protection against severe disease and hospitalization
- Evidence continues to suggest a first dose of the AstraZeneca vaccine followed by a second dose of the Pfizer mRNA vaccine has a good safety profile
- Individuals who received a
first dose of an mRNA vaccine can receive either mRNA vaccine for their second dose, though they should receive the same mRNA product as their first dose if it is on hand
Provincial Recommendations
The Ministry has indicated the following, which can be found on their COVID-19 Vaccines: Getting Your Second Dose webpage.
For patients who received
- AstraZeneca: can get AstraZeneca, Moderna, or Pfizer for their second dose when eligible and it is at least 8 weeks after their first dose with informed consent.
- Moderna or Pfizer: can get either Moderna or Pfizer when eligible and it’s at least
28 days after their first dose. They can switch between Moderna and Pfizer safely.
All of these options are safe, provide strong protection against COVID-19, including the Delta variant and will count as a completed series.
Simultaneous Administration of Vaccines
- As a precaution, NACI continues to recommend that COVID-19 vaccines and non-COVID-19 vaccines should not be routinely given at the same time
- If possible, COVID-19 vaccines should be given at least 14 days after
and 28 days before other vaccines, with some exceptions. This will help to avoid possible overlapping side effects and potential (but unknown) interference with the immune response between vaccines.
- There may be circumstances when a non-COVID-19 vaccine needs to be administered within 28 days after a COVID-19 vaccine. Examples include when a non-COVID-19 vaccine is needed after an exposure to another infectious disease or when an individual is about to start a treatment that will weaken their immune system. A shorter interval between vaccinations should be used in these circumstances.
Out of Province/Country vaccination recommendations
- Patients who have either started or completed their COVID-19 vaccine series outside of Ontario or Canada with a vaccine NOT currently authorized by Health Canada are recommended to restart their COVID-19 vaccine series with a Health Canada authorized COVID-19 vaccine. Patients would be eligible to restart their COVID-19 vaccine series 28 days after their last vaccine.
- A completed vaccine series from outside of Canada is currently considered valid by the Ontario government,
but there is no guarantee that this will remain the case, nor that other jurisdictions and organizations will recognize it. Not all vaccine series elsewhere in the world are as effective as the vaccines approved by Health Canada.
- As a practical matter to ensure patients are recognized as vaccinated in the future, and as an ethical matter to ensure all persons have opportunity to receive equivalent protection against COVID-19, a Health Canada approved vaccine series is recommended to anyone who has not already been vaccinated with one.
For More Information
- Summary of NACI Statement – June 17, 2021
- Call the COVID-19 Primary Care Info-Line at 905-688-8248 (press 7, then 1 for physicians). The info-line is open Monday to Friday, 9:15 a.m. to 4:15 p.m.
- Remind your patients to visit Public Health’s COVID-19 vaccination webpage for up-to-date information