Questions about Booster Doses

Why are booster doses of the COVID-19 vaccine needed?

Canada’s National Advisory Committee on Immunization (NACI) has released guidance on booster COVID-19 vaccine doses in Canada with the following objectives: minimize serious illness and death, to preserve health care capacity, and reduce transmission to protect high risk populations.

Booster doses of COVID-19 vaccines can increase the immune response and offer more and longer-lasting protection against infection.

Who should get an initial (first) booster dose of the COVID-19 vaccine?

Individuals 12 years of age and older who have received a primary COVID-19 vaccine series are eligible to get an initial booster dose of an mRNA COVID-19 vaccine (Pfizer Comirnaty® or Moderna Spikevax®) at least 6 months after receiving the last dose in the primary series of the COVID-19 vaccine. Individuals 18+ years of age can now receive Moderna Spikevax Bivalent vaccine for their booster dose.

It is recommended that individuals wait 6 months after their last dose before receiving a booster dose of COVID-19 vaccine. A booster dose may be given as early as 3 months after the last dose of vaccine in situations where a person needs to receive the vaccine earlier (for example, starting medical treatment or traveling to a region where there a high number of COVID cases).

A booster dose (2nd dose) of the Janssen (Johnson & Johnson) COVID-19 vaccine may be given to individuals 18 years of age and older at least 2 months after receiving the first dose.

Janssen (J&J) may be administered as a booster vaccine to those who may have a contraindication (for example, an allergy) to an mRNA vaccine or the Novavax NuvaxovidTM vaccine, or any of their components.  For these cases only, NACI recommends that they may be offered viral vector COVID-19 vaccines, including the Janssen (J&J) vaccine, as a booster dose.

Who should get a second booster dose of the COVID-19 vaccine?

Recently, NACI recommended a second booster dose of COVID-19 vaccine for everyone age 12 and older at 6 months after their last booster dose. This recommendation was made in anticipation of an increased number of COVID-19 cases in autumn of 2022. Specifically, NACI strongly recommends the following groups receive a booster dose (regardless of the number of previous doses received):

  • Older adults (≥65 years of age) 
  • Residents of long-term care facilities or congregate living settings for seniors
  • Individuals 12 years of age and older with an underlying medical condition that places them at high risk for severe COVID-19
  • Adults in or from First Nations, Métis, or Inuit communities, where infection can have disproportionate consequences 
  • Adults in racialized communities and marginalized communities (e.g., people living with disabilities) disproportionately affected by COVID-19
  • Residents of other congregate living settings (e.g., quarters for migrant workers, shelters, correctional facilities, group homes) who are 12 years of age and older.

NACI provides a discretionary recommendation for all other individuals 12 to 64 years of age be offered a COVID-19 booster dose (regardless of the number of booster doses previously received) at 6 months after their last dose of vaccine.

Eligible individuals previously infected with COVID-19 should wait for 3 months after symptom onset or positive test (if asymptomatic) provided it is at least 6 months from the last dose of vaccine.

Is a booster dose recommended for children under the age of 5?

Currently, a booster dose of the COVID-19 vaccine is not recommended for children under 5 years of age. 

How many doses are recommended for individuals who are moderately to severely immunocompromised?

The National Advisory Committee on Immunization (NACI) has recommended an additional dose of the COVID-19 vaccine for those who are moderately or severely immunocompromisedin order to provide additional protection against the virus.

Those who are moderately to severely immunocompromised will need three doses of vaccine to complete their primary series:

  • active treatment for solid tumour or hematologic malignancies
  • receipt of solid-organ transplant and taking immunosuppressive therapy
  • receipt of chimeric antigen receptor (CAR)-T-cell therapy or hematopoietic stem cell transplant (within 2 years of transplantation or taking immunosuppression therapy)
  • moderate to severe primary immunodeficiency (e.g., DiGeorge syndrome, Wiskott-Aldrich syndrome)
  • Stage 3 or advanced untreated HIV infection and those with acquired immunodeficiency syndrome
  • active treatment with the following categories of immunosuppressive therapies: anti-B cell therapies (monoclonal antibodies targeting CD19, CD20 and CD22), high-dose systemic corticosteroids (e.g. 20 mg/day for ≥ 14 days), alkylating agents, antimetabolites, or tumor-necrosis factor (TNF) inhibitors and other biologic agents that are significantly immunosuppressive.
  • Dialysis patients

At 6 months after the completion of the primary series (3 doses), a booster dose of an mRNA COVID-19 vaccine (Pfizer Comirnaty® or Moderna Spikevax®) is strongly recommended.

A 2nd booster dose is recommended 6 months after the 1st booster dose has been administered.

    Where and when can I get a booster dose of the COVID-19 vaccine?

    Residents of long-term care facilities will receive their booster doses at those facilities.

    Individuals who meet the eligibility criteria for a first and/or second booster dose can make an appointment to get a booster dose at either a COVID-19 Vaccine Clinic or a participating pharmacy.

    Moderately to severely compromised individuals should wait at least 28 days after receiving their second dose of the COVID-19 vaccine before receiving a third dose in the primary series.

    I’ve already had COVID-19 and am fully vaccinated, do I still need to get a booster dose? 

    Even if you've already had COVID-19 and recovered, you should still get your booster dose. While you may experience some increase in immunity after being infected with COVID-19, that is not enough to increase your overall immunity over a longer period of time. Getting a booster dose, even after having COVID-19, will provide increased and longer-lasting protection to reduce future infection, community transmission and severe illness.

    If you were recently infected, you can get your first booster dose 3 months after you first experienced symptoms of COVID-19 or since the date of your positive test (provided it has been 6 months since your last dose of vaccine). 

    If you were recently infected and have already received a first booster dose and are now eligible to receive a second booster dose, you should also wait 3 months after you first experienced symptoms of COVID-19 or since the date of your positive test to receive your second booster dose.

    Am I still considered “fully vaccinated” if I don’t get a booster dose? 

    Yes, you are still considered fully vaccinated two weeks after getting your second dose in a two-dose series (e.g. Pfizer-BioNTech ComirnatyTM, and Moderna SpikevaxTM, AstraZeneca VaxzevriaTM , Novavax NuvaxovidTM vaccines vaccines), or two weeks after a single-dose vaccine, such as the J&J/Janssen vaccine.

    If we need a booster dose, are the vaccines working? 

    Yes. COVID-19 vaccines are working well to prevent severe illness, hospitalization, and death. However, public health experts are starting to see reduced protection from the primary vaccine series over time against mild and moderate disease, especially among certain high-risk populations. Getting a booster dose after receiving your primary series of the vaccine will increase and extend protection against the virus. 

    How does the booster dose better protect me from COVID-19 variants? 

    Clinical trials show that a booster dose increases the immune response in people who have finished a COVID-19 vaccine primary series 6 months earlier or who received a J&J/Janssen single-dose vaccine 2 months earlier. With an increased immune response, people should have improved protection against getting infected with COVID-19.

    I received the Pfizer-BioNTech ComirnatyTM vaccine for my first two doses, is it safe/effective to get the Moderna SpikevaxTM or Moderna SpikevaxTM Bivalent vaccine for my booster dose(s)? 

    Yes. Either Moderna Spikevax, Pfizer-BioNTech Corminaty or Moderna Spikevax Bivalent, vaccines may be used as a booster dose (regardless of which COVID-19 vaccine was used in the primary series). Moderna Spikevax Bivalent is indicated only for those 18+ years of age as a booster dose. 

    Can I receive Novavax Nuvaxovid as a booster dose after receiving a mRNA or viral vector vaccine?

    Yes. Novavax Nuvaxovid can be administered as booster dose to individuals who are unable or unwilling to receive a booster dose of mRNA or viral vector vaccine.

    Are vaccines effective at preventing the spread of the Omicron variant?

    As per a recent statement by the Canadian Council of Chief Medical Officers of Health, “while data remains limited at this time, there is emerging evidence that two doses of a mRNA vaccine are less effective at preventing Omicron infection compared to previous variants but does indicate good protection against more severe disease requiring hospitalization. We also know that a booster dose is a valuable tool to offer protection from infection and do expect that a booster dose will offer very good protection against severe disease. While we do not know how long protection from boosters will last, this is an important tool at this time to help protect our collective progress against COVID-19 and preserve health care system capacity.” The full statement can be found here.

    Published date: 
    September 20, 2022
    Health and Wellness

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