TORONTO – The Council of Ontario Medical Officers of Health (COMOH) is urging Ontarians to get fully vaccinated against COVID-19 as soon as they are eligible, and to take the first vaccine that is offered to them for their first or second dose. Both Pfizer and Moderna vaccines are interchangeable and can be received as second dose vaccination regardless of the first dose provided. Either can also be received following first dose vaccination with AstraZeneca vaccine.

With the large shipments of Moderna vaccine arriving and the reduction in Pfizer vaccine at this time, Moderna vaccine will be provided as a second dose following Pfizer as a first dose frequently throughout the province. Based on recent recommendations by the National Advisory Committee on Immunization (NACI), either of these mRNA vaccines as a second dose is both safe and effective, and offers strong protection against COVID-19, including the more contagious and severe Delta (B.1.617) variant. With the increase in the Delta variant in Ontario it is important for people to have two doses in order to be more fully protected.

“Two doses of COVID-19 vaccine provides a high degree of protection against infection from COVID-19 including serious illness, hospitalization and death.” Dr. Charles Gardner, Chair of the Council of Ontario Medical Officers of Health (COMOH). “I urge all people 12 years of age and over who have not had their first dose to do so as soon as possible, and everyone to receive their second dose as soon as you are eligible.”

Both Moderna and Pfizer vaccines are authorized for use in Canada and use a similar mRNA technology, so the vaccines are interchangeable. In addition, those who have had AstraZeneca vaccine for their first dose can take as a second dose AstraZeneca, with either Moderna or Pfizer as being more advisable. Mixing vaccine products to complete a series is commonly done with immunizations against a number of other diseases such as Hepatitis A and B, Tetanus and Meningitis.

For more information about COVID-19 vaccination and eligibility to receive a vaccine, please visit the Ontario government COVID-19 vaccination website.

As the provincial organization representing public heath, alPHa provides leadership and expertise on public health management issues. Its members include medical officers of health, board of health members and senior managers in public health disciplines including inspection, epidemiology, nursing, dentistry, nutrition, health promotion and business administration.

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