Second dose

You will receive an mRNA vaccine at HPPH community clinics (either Moderna or Pfizer-BioNTech, depending on supplies and age eligibility). 

  • The National Advisory Committee on Immunization strongly recommends an optimal interval of eight weeks between first and second doses of a two-dose COVID-19 vaccine series. This will provide you with increased and longer-lasting protection from the vaccine. Individuals who wish to get their second dose at a shorter interval (e.g. 21-28 days), as applicable, can continue to do so but with informed consent. 
  • If you received AstraZeneca for your first dose, the earliest date you can receive your second dose of vaccine is 8 weeks after your first dose (with informed consent).
  • Use the HPPH vaccine dose calculator below to find out the earliest date you are eligible for a second dose.

Individuals who received a first dose of a COVID-19 vaccine outside of Ontario need to complete the COVID-19 Out-of-Province Dose Documentation form prior to booking an appointment for a second dose.

Vaccine dose calculator

Use the HPPH COVID-19 vaccine dose calculator to find out the earliest date you are eligible for your next dose of vaccine.

 Vaccine dose calculator

Booking your second dose

The Pfizer-BioNTech, Moderna and AstraZeneca/COVISHIELD vaccines require two doses. Anyone born in 2016 or earlier can book an appointment for their first or second dose of the COVID-19 vaccine in Ontario. Youth ages 12 to 17 and children ages 5 to 11 may only receive the Pfizer-BioNTech vaccine, with the paediatric Pfizer COVID-19 vaccine available to children ages 5 to 11.

You can subscribe to our Get a vaccination webpage to receive alerts when new clinics are added using the "Subscribe to page updates" button on the bottom right-hand side of the page.

HPPH does not book second dose appointments when you get your first dose. You are responsible for booking your second dose.

Mixing vaccines

Canada's National Advisory Committee on Immunization (NACI) has updated its recommendations on vaccine interchangeability or "vaccine mixing." Mixing vaccines is not a new concept. For example, similar vaccines from different manufacturers are sometimes used to complete a vaccine series for influenza, hepatitis A and other illnesses.

Pfizer and Moderna are interchangeable mRNA COVID-19 vaccines. This means that you can receive one vaccine for your first dose and the other vaccine for your second dose.

  • Make your second dose a priority.
  • Whether it's the same vaccine or a mix of two vaccines, being fully vaccinated is valuable. Two doses of vaccine provides good protection against COVID-19 and variants, including the highly transmissible Delta variant.
 I received Pfizer or Moderna as my first dose.
  • Children ages 5 to 11 years of age may only receive the Paediatric Pfizer COVID-19 vaccine. 
  • Individuals 12 to 17 years of age may only receive the Pfizer-BioNTech vaccine as their second dose.
  • Individuals 18 and older may receive either the Pfizer-BioNTech or Moderna vaccine as their second dose.
    • Note: Based on the advice of Ontario’s Children COVID-19 Vaccine Table, Ontario Vaccine Clinical Advisory Group, and Public Health Ontario, the Pfizer vaccine is recommended for ages 18 to 24 to minimize myocarditis risk.
  • Pfizer-BioNTech and Moderna are interchangeable mRNA COVID-19 vaccines; this means you can receive one for your first dose and the other for your second dose.
  • The National Advisory Committee on Immunization strongly recommends an optimal interval of eight weeks between first and second doses of a two-dose COVID-19 vaccine series. This will provide you with increased and longer-lasting protection from the vaccine. Individuals who wish to get their second dose at a shorter interval (e.g. 21-28 days), as applicable, can continue to do so but with informed consent. 
  • Use our vaccine dose calculator to find out when you can receive your second dose.
 I received AstraZeneca as my first dose.
  • If you received AstraZeneca for your first dose, the earliest date you can receive your second dose of vaccine is 8 weeks after your first dose, whether you receive AstraZeneca or an mRNA vaccine for your second dose.
  • If you received AstraZeneca as your first dose, you can choose to receive a second dose of AstraZeneca or an mRNA vaccine (Pfizer or Moderna) at an 8 to 12-week interval.
    • There is evidence that a longer interval between two doses (12-week interval) provides higher protection. However, some people may choose to receive their second dose earlier to have the increased protection of a second dose sooner.
    • Some, in consultation with their health care provider, may need to book earlier than 8 weeks due to their medical treatment schedule.
  • If you would like to have AstraZeneca as your second dose you can:
  • Choose to have an mRNA vaccine (Pfizer or Moderna) as your second dose at least 8 weeks after your first dose.