Interchanging vaccines for COVID-19 second doses

Special to WC Online

OTTAWA – Ottawa Public Health (OPH) encourages Ottawa residents to take the first COVID-19 vaccine available for your second dose to provide earlier two-dose protection which is recommended where variants of concern are circulating.

On June 1, the National Advisory Committee on Immunization (NACI) updated its recommendations on the interchangeability of COVID-19 vaccines used in Canada.

“This means you could receive one vaccine for your first dose and a different vaccine for your second dose to complete your COVID-19 vaccine series,” city staff released in a statement today (June 17). “Interchanging vaccines is safe and effective and is not a new practice. Similar vaccines from different manufacturers are used when vaccine supply or public health programs change. Different vaccine products have been used to complete a vaccine series for influenza, hepatitis A, and others.”

The priority is to receive two doses of a vaccine to complete the series and be fully protected. Both mRNA vaccines, Moderna and Pfizer, are made the same way. Getting the same vaccine for your first and second doses or getting one vaccine for your first dose and a different vaccine for your second dose (also called a “mixed schedule”), are both considered valid options. 

“Moderna and Pfizer have very similar effectiveness and side effects,” city staff said. “The best vaccine you can get is the first one that is available to you and a second dose of a COVID-19 vaccine is needed for the best protection against COVID-19 and its more transmissible variants. All COVID-19 vaccines approved for use in Canada are safe and effective and they all reduce the risk of serious illness, hospitalization, and death, and will help with the control of COVID-19 in the community.”

If you received AstraZeneca/COVISHIELD as your first dose, NACI recommends that you receive either AstraZeneca/COVISHIELD vaccine or an mRNA vaccine, such as Moderna or Pfizer, for your second dose. For more information on mixed vaccine schedules, please review NACI’s Interchangeability of Authorized COVID-19 Vaccines.  Note that Ontario no longer offers AstraZeneca vaccine for those who have not received a first dose of AstraZeneca. For further information please contact your primary care provider.

Residents can visit  to access the provincial booking system or call the provincial vaccine booking line at 1-833-943-3900 between 8 a.m. and 8 p.m., seven days a week. Only book or call if you are eligible. Everyone is eligible to book a second dose vaccination at the standard 16-week interval in Ontario, but only those living in certain congregate settings or with certain medical conditions, highest-risk healthcare workers and those vaccinated prior to April 18 are eligible to book at shortened dose intervals at this time in Ottawa.

You may also be able to book your vaccine appointment at a local pharmacy. Most pharmacies book appointments ahead of time and some allow walk-ins. Eligible residents should check with the pharmacy directly. Select primary care teams are also offering vaccines. Residents may also be eligible to book their second dose vaccination at a pop-up clinic or at Bruyère vaccine clinic. Please visit to verify eligibility and book your appointment.

Follow the city’s social media channels for updates on the provincial booking system. Sign up for the COVID-19 vaccination update e-subscription for regular news on the vaccine roll-out. 

Visit or  for more information on Ottawa’s vaccination distribution plan.

For more information on City programs and services, visit or call 311 (TTY: 613-580-2401). 

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