The 2nd dose of COVID-19 vaccine is necessary: 

  • it reduces the risk of acquiring and transmitting COVID-19;
  • it increases protection rate of the vaccine;
  • it provides optimal protection in the longer term.

One week after receiving the second dose you will be adequately protected.

The recommended interval is 8 weeks or more between doses of COVID-19 vaccines.

Making an appointment for the 2nd dose

The appointment for the 2nd dose is made when you get the 1st dose.

Changing the appointment for the 2nd dose

People 40 years of age and older can change the 2nd dose appointment online. For other age groups, the modification can be made from the date indicated in the following calendar. Make sure that the minimum interval of 8 weeks between doses is respected.

  • June 18: 35 years old and over
  • June 21: 30 years old and over
  • June 22: 25 years old and over
  • June 23: 18 years old and over

Changing the second dose appointment

If you have difficulties ask your loved ones for help. If you do not have access to the online platform, call 1‑877‑644‑4545 (toll free).

If you get an error message when changing your appointment, please go to a walk-in vaccination clinic or the pharmacy where you received your first dose to correct your information and be vaccinated depending on vaccine availability.


  • The sequence only takes place by age group, even if you were in another target group when you received your first dose (e.g. essential workers, chronic diseases, etc.)
  • Changing your appointment for the 2nd dose is not mandatory. The 2nd dose appointment that was given to you when you received your 1st dose is still booked.
  • Vaccination appointments become available depending on the availability of doses.
  • It is the age that is considered when making the appointment, and not the year of birth.
  • When you make a new appointment to advance the 2nd dose, the one taken at the 1st dose will be automatically canceled. Your new appointment will be made at the same vaccination centre of your 1st dose.

People who are highly immunosuppressed or who are on dialysis

People who are highly immunosuppressed or who are on dialysis are considered to have a very high risk of complications from COVID-19. These people will be able to get the 2nd dose of vaccine 28 days after the 1st dose. The people concerned will be contacted to schedule their appointment.

Second dose for people who received the Covishield or AstraZeneca vaccines

People 18 years of age and older who received the Covishield or AstraZeneca vaccine for the 1st dose could receive a Pfizer or Moderna vaccine for their 2nd dose. According to the Comité sur l'immunisation du Québec, it appears preferable that people who have received a 1st dose of AstraZeneca vaccine to receive an mRNA vaccine (Pfizer or Moderna) as a 2nd dose.

Administration of Pfizer or Moderna vaccine at least 8 weeks after a dose of AstraZeneca or Covishield vaccine does not appear to cause more reactions than 2 doses of RNA vaccine.

However, the Covishield or AstraZeneca vaccine can be given to people 18 years of age and older for whom messenger mRNA vaccines are contraindicated or who prefer to complete their vaccination with the same product.

At the vaccination centre, Pfizer or Moderna vaccine (depending on the availability of doses) will be offered, as recommended by the Comité sur l'immunisation du Québec. However, you can receive a 2nd dose of AstraZeneca.

Visit the COVID-19 messenger RNA vaccine and COVID-19 viral vector-based vaccine pages to learn more about these vaccines.

People who have received a Covishield or AstraZeneca vaccine in the 1st dose and who wish to advance their appointment for their 2nd dose are invited to go to Changing the appointment for the 2nd dose.

Walk-in clinics

Walk-in clinics are set up for the second dose. Before you come in for your second dose, make sure it has been at least 8 weeks since your first dose. Do not go to the vaccination clinic if you are in quarantine (self-isolate).

See the details for the vaccination clinic nearest to you:

Other measures

The majority of the population will need to have received 2 doses of the vaccine in order to sufficiently reduce the transmission of COVID-19. In the meantime, health instructions measures such as physical distancing of 2 metres, wearing a mask or face cover and hand washing should continue to be strictly observed by vaccinated persons until further notice.