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Delay in Pfizer Delivery Means More People Will Be Getting Moderna As Their Second Dose

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London, ON – In order to meet the challenges associated with a delayed delivery of Pfizer mRNA vaccine to the region next week, three mass vaccination clinics in the Middlesex-London region will only be providing the Moderna mRNA vaccine to adults this coming week. Starting Monday, June 21, Western Fair Agriplex, North London Optimist Community Centre and the Caradoc Community Centre in Mount Brydges will be offering only the Moderna mRNA vaccine to those over the age of 18 who attend for a first or second dose appointment. A limited supply of Pfizer will be available at each clinic exclusively and only for youth aged 12 to 17 years old.

In order to get as many people vaccinated as quickly as possible, it is important that individuals take the first available mRNA vaccine for their second doses. The interchangeability of mRNA vaccines has been supported by experts at both the Public Health Agency of Canada and the National Advisory Committee on Immunization. Interchangeability means that you can receive either the Pfizer or Moderna mRNA vaccine as your second dose, regardless of the type of vaccine you received for your first dose. This concept is an important component of the Health Unit’s effort to deliver more vaccine to as many people as quickly as possible.

“Regardless of which vaccine you received for your first dose, Moderna is an excellent vaccine for your second dose,” says Dr. Chris Mackie, Medical Officer of Health at the Middlesex-London Health Unit, “Pfizer and Moderna are essentially different brands of the same vaccine, and you will have the same protection against COVID-19 regardless of what you get for your first or second dose.”

How to book an earlier second-dose appointment:

  • Book online at (new appointments open daily at 8:00 a.m.)

    - For those vaccinated on or before May 9th who want to re-schedule an earlier second dose appointment, enter Gate #4 I need to re-book my scheduled second dose.
    For those who received their first dose in another setting or region and need to book a second dose, enter Gate #5, I received my first dose elsewhere and now need to book a second dose.

  • Phone lines are often busy, and online is the recommended route for rebooking. However, calling remains an option at 226-289-3560 (8:00 a.m. to 7:30 p.m., Monday to Sunday)

The Health Unit is also reminding the public that online booking is now available for MLHU’s upcoming Pop-up Community Clinics. Many appointments are still available at Sir Arthur Carty Catholic Elementary School on Monday, June 21 from 1:30 to 6:30 p.m. To make an appointment, book online, enter Gate #7: To view the full schedule of Pop-up Community Clinics visit:

For more information about how to book or cancel a COVID-19 vaccine appointment, visit:

Media Contact:
Beth Milne, Communications Supervisor, Middlesex-London Health Unit,
519-617-0564 (cell.)

Dr. Chris Mackie, Medical Officer of Health, Middlesex-London Health Unit


Tags: COVID-19 Vaccine