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 18 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.