COVID-19: Vaccine Eligibility & Doses

A primary series is typically the first two or three doses, with the original (monovalent) mRNA vaccines, needed for a strong initial immune response.

Everyone aged 6 months and older is currently eligible to receive a COVID-19 vaccine. Children must be at least 6 months old at the time of vaccination. The original (monovalent) COVID-19 mRNA vaccines, Pfizer BioNTech (including the Pediatric vaccine) and Moderna, are the best vaccine choice because of the strong immune protection they provide against severe illness and hospitalization, and their well-known safety profiles.

The Pfizer-BioNTech, Moderna Spikevax, Novavax Nuvaxovid and AstraZeneca/COVISHIELD vaccines require two doses. For children 6 months to under 5 years of age, the Pediatric Pfizer (3 mcg) vaccine requires three doses.

For children ages 6 months to 4 years old, there is no preferred vaccine as both of the original mRNA products will provide strong protection against COVID-19 and its variants. The Pfizer vaccine is strongly recommended for people 5 to 29 years of age. See messenger RNA (mRNA) vaccines for more information.

Children/youth, 17 years of age or younger, should talk about the benefits and risks of getting the vaccine with a parent or trusted adult. This includes understanding information about the vaccine, why it is being recommended and what will happen if they accept or refuse vaccination. Parents or legal guardians of younger children will usually have to provide consent on behalf of the child before or at the time of the appointment.

The Novavax COVID-19 vaccine is an option for people 12 years of age and older, who have not been able, due to contraindications, or are not willing to receive a mRNA COVID-19 vaccine. It can also be used to complete a primary series that was started using a viral vector vaccine.

Interval between doses

To further improve protection and effectiveness of the vaccine, the National Advisory on Immunization (NACI) and the Ministry of Ontario has recommended 8 weeks as the optimal interval between doses in the primary series. Evidence will continue to be monitored and information will be updated as needed.

• A primary series completed with two to three doses at eight weeks apart, including any booster(s) when eligible, continues to protect adults and children from severe illness ensuring a strong immune response against variants, such as Omicron, and any future variants.
• An 8 week interval is associated with a lower rate of side effects.
• Data suggests that protection can be improved when the interval between the first and second doses are extended beyond the original manufacturer’s recommended interval (e.g., 21 days between first and second dose of a Pfizer-BioNTech COVID-19 vaccine).
• Individuals may choose to speak with their primary care provider about what interval is best for them. The authorized interval may still be used.
• Interruption of a vaccine series resulting in a greater interval between doses than recommended does not require re-starting the series.

Learn more about the administration of the COVID-19 vaccine, information about the vaccines, vaccine use by age, and where to get vaccinated.

Some people who have weakened immune systems may have a lower antibody response to the two or three-dose series due to their underlying condition(s). Getting three or four doses of the COVID-19 vaccine, as part of your first COVID-19 vaccine series, is recommended for people who are moderately to severely immunocompromised to help build antibodies and for better long-term protection.

It is important to speak with your doctor or specialist about the timing for you to have the best possible immune response from the vaccine and minimize delays in your treatment and advise the health care provider giving you the vaccination that you are immunocompromised.

A third or fourth dose of the original (monovalent) vaccine can be given at a minimum of two months (56 days) after the previous dose.

• For children ages 6 months to 4 years old, the monovalent Moderna (25mcg) is preferred and recommended by NACI. This will allow children to complete their primary series after three doses instead the four doses needed with the monovalent Pfizer-BioNTech (3mcg).
• For children ages 5 to 11 years old, the pediatric Pfizer-BioNTech (10mcg) vaccine should be given.
• For ages 12 to 29 years old, Pfizer BioNTech (30mcg) is recommended and preferred. With informed consent, adults 18 to 29 years old may receive a full dose of Moderna (100mcg).
• For ages 30 and older, a full dose of Moderna (100mcg) or PfizerBioNTech (30mcg) should be given.

A COVID-19 booster is a vaccine dose given after you have completed the primary vaccine series. It helps improve protection against COVID-19 that may have decreased over time and boosts the immune response even if you had a COVID-19 infection in the past. Health Canada authorized mRNA vaccines (Pfizer-BioNTech and Moderna Spikevax) and Novavax Nuvaxovid as booster doses regardless of which vaccine was used for your primary series.

The interval between the doses depends on the vaccine you receive, your age, your health status and if you recently had a COVID-19 infection.

It is recommended that everyone ages 5 and older get one mRNA COVID-19 booster (original or bivalent) on or after September 1, 2022:

• six months after a COVID-19 vaccine dose or a COVID-19 infection. Three months (84 days) may be considered based on age, risk and health status.
• A bivalent mRNA vaccine is preferred.

The mRNA COVID-19 vaccines provide good protection against hospitalization and severe illness within the 3 to 6 months following vaccination. According to the National Advisory Committee on Immunization (NACI), it is not expected that a booster dose be routinely given every three months.

As of March 3, 2023, NACI recommends an additional COVID-19 bivalent booster in the spring of 2023 for people who are at high risk of getting very sick from COVID-19. The Ministry of Health will provide further eligibility details soon.

Booster dose eligibility

The bivalent mRNA boosters are recommended over monovalent boosters and is not currently authorized for use in a primary series.

Once eligible, the following groups may receive a booster dose six months after a COVID-19 vaccine dose or a COVID-19 infection:

• Infants and children 6 months to 4 years of age are not eligible at this time.
• Children 5 to 11 years of age – the bivalent Pfizer-BioNTech (10mcg) vaccine is preferred.
  • Children 6 to 11 years of age may be given the bivalent Moderna (25 mcg) with informed consent, while supply is available.
• Youth 12 to 17 years of age – the bivalent Pfizer-BioNTech (30mcg) vaccine is preferred.
  • With informed consent, the bivalent Moderna (50 mcg) may be offered to those with weakened immune systems.
• Adults 18 years of age and over may receive either mRNA bivalent booster dose (Pfizer-BioNTech or Moderna)

The original (monovalent) vaccines are to be used for all primary series vaccinations because they provide a strong initial immune response. For people who are not able or willing to get a bivalent mRNA booster dose, the original vaccine may be given.

With informed consent, all COVID-19 booster vaccines for people aged 5 years and older, can be given with, or at any time before or after, non-COVID-19 vaccines.

Novavax Nuvaxovid (0.5mL) is an option for people 12 years of age and older, who have not been able, due to contraindications, or are not willing to receive a mRNA COVID-19 booster vaccine.

People who received Janssen COVID-19 vaccine for their primary series are recommended to receive a mRNA COVID-19 vaccine for their booster dose.

Book an appointment for a booster dose at our City-run clinics or pharmacies. Find out where to get vaccinated.

Note: People who are moderately to severely immunocompromised may use this referral form or letter from your physician, to identify optimal timing for vaccination.

More Information:

• City of Toronto: COVID-19: Where to Get Vaccinated
• Ministry of Health: COVID-19 Vaccine Guidance

* Moderate to severely immunocompromised populations (if 5 years of age and over) and residents (65+) of long-term care homes, retirement homes, elder care lodges and other senior congregate settings are eligible for a three dose primary series plus a booster (if 5 years of age and over) ** Referral is required from an allergist/immunologist or another specialist where a confirmed allergy exists to components of the mRNA vaccines or there are concerns in accessing a mRNA vaccine.

Re-vaccination is recommended with a new COVID-19 vaccine primary series (3 doses) and booster given the loss of immunity following:

• hematopoietic stem cell transplant (HSCT)
• hematopoietic cell transplants (HCT) (autologous or allogeneic)
• CAR-T-cell therapy

Optimal timing should be determined on a case-by-case basis in consultation with your clinical team.

Please bring your referral form/letter to EACH of your vaccination appointments, highlighting this is to restart your primary series.

Everyone aged 6 months and older, without OHIP cards, may get vaccinated at any clinic or pharmacy clinic offering COVID-19 vaccines. Appointments for City immunization clinics must be made through the Provincial Vaccine Contact Centre at 1-833-943-3900.

Required Identification

For all clinics, bring an acceptable form of identification which may include non-Canadian and expired documents such as a driver’s licence or passport, a piece of mail with your name on it, a pay stub or a student card. Those 18 or older must provide photo ID.

Vaccines Authorized by Health Canada

• If you received one dose of a two dose series outside Ontario, you should document this dose and you should get the second dose as soon as you are eligible. Do not wait for your previous dose to be documented before getting your final dose.
• If you have received all recommended doses or a combination of Health Canada authorized vaccines within the minimum recommended interval, after documenting the out of province dose(s) you will be considered to have a complete vaccine series and no additional doses are needed.

Vaccines approved for use in Canada are currently Comirnaty (Pfizer-BioNTech), SpikeVax (Moderna), Vaxzevria (AstraZeneca), and the single-dose Janssen (Johnson & Johnson).

Vaccines Not Authorized by Health Canada

• If you have received and documented one or two doses of a COVID-19 vaccine not authorized for use by Health Canada, you will be considered to have received a full vaccine primary series by getting one additional dose of a mRNA vaccine. Do not wait for your previous dose(s) to be documented before getting your final dose.
  • The interval between your previous dose and the additional dose should be at least 28 days
  • If you already received three doses of a non-Health Canada authorized COVID-19 vaccine at the minimum intervals, you should not receive any additional primary series doses at this time

Unsure About Which Vaccine You Received

• If you received a previous dose and you do not have proof of vaccination, please contact the health care provider who gave you the COVID-19 vaccine(s) to receive a copy of your vaccination record.
• If the COVID-19 vaccine product used for your previous dose(s) remains unknown, or if written proof of vaccination is provided for a vaccine whose generic or trade name is not recognized, a new vaccine series should be started with a Health Canada authorized COVID-19 vaccine.
  • If you know the date of your previous COVID-19 immunization, wait at least 28 days before getting a new Health Canada authorized COVID-19 vaccine series.

If you are eligible for an additional dose(s), including a mRNA dose needed to complete your series or a booster dose, you can book an appointment at any City-run immunization clinic using your green photo Ontario Health Card (OHIP) number through the  provincial portal or by calling 1-833-943-3900 (TTY 1-866-797-0007). With an older red and white OHIP card number or with no OHIP number at all you can book an appointment by calling 1-833-943-3900 (TTY 1-866-797-0007). Walk-in appointments are also accepted. You do not need to wait until your out-of-province dose(s) is documented by Toronto Public Health.

Even with a previous COVID-19 infection, people who have not started/completed their primary series or those who are eligible for a booster dose, are still strongly recommended to complete their COVID-19 series. Immunity from an infection may not last and people can be infected with COVID-19 again.

Hybrid immunity means having protection from being vaccinated for COVID-19 and a recent past COVID-19 infection. A past COVID-19 infection can provide natural immunity, but it does not last long – especially with Omicron variants. You have a higher risk of getting COVID-19 again if you are not up-to-date with your vaccinations.

If you have had COVID-19 in the past you should still stay up to date with your vaccinations to get the benefit of hybrid immunity.

Every COVID-19 infection increases the risk for long COVID. To maximize the immune response after you have had COVID‑19, you should wait the following intervals after symptoms started or a positive test (if you had no symptoms) before receiving your next dose:

If completing your primary series:

• two months (56 days) if you are not immunocompromised and have no history of multisystem inflammatory syndrome in children (MIS-C)
• one to two months (28 to 56 days) if you are immunocompromised but have no history of MIS-C
• if you have a history of MIS-C, until clinical recovery has been achieved or up to 90 days since the onset, whichever is longer, regardless of immunocompromised status

If getting a booster dose:

• at least three months (84 days); however, six months (168 days) may provide better immune response