COVID-19 Information on Vaccine Third Doses

Third Doses for Eligible Medical Conditions and Residents of High-Risk Congregate Settings

As of September 14, 2021, based on the recommendation of the Chief Medical Officer of Health and health experts, Ontario expanded the list of individuals who are eligible for a third dose of a COVID-19 vaccine to include:

  • Those undergoing active treatment for solid tumors;
  • Those who are in receipt of chimeric antigen receptor (CAR)-T-cell;
  • Those with moderate or severe primary immunodeficiency (e.g., DiGeorge syndrome, Wiskott-Aldrich syndrome);
  • Stage 3 or advanced untreated HIV infection and those with acquired immunodeficiency syndrome; and
  • Those undergoing active treatment with the following categories of immunosuppressive therapies: anti-B cell therapies (monoclonal antibodies targeting CD19, CD20 and CD22), high-dose systemic corticosteroids, alkylating agents, antimetabolites, or tumor-necrosis factor (TNF) inhibitors and other biologic agents that are significantly immunosuppressive.

This expanded eligibility adds to the list released previously on August 17, 2021:

  • Transplant recipients (including solid organ transplant and hematopoietic stem cell transplants)
  • Patients with hematological cancers (examples include lymphoma, myeloma, leukemia) on active treatment (chemotherapy, targeted therapies, immunotherapy) for malignant hematologic disorders
  • Recipients of an anti-CD20 agent (e.g., rituximab, ocrelizumab, ofatumumab)
  • Residents of high-risk congregate settings including long-term care homes, higher-risk licensed retirement homes and First Nations elder care lodges. Vaccinations for this group will be coordinated through their housing organization.


Health care providers will contact their eligible patients. If you think you may be eligible, contact your health care provider. If you live in a high-risk congregate setting, contact your housing organization for details on their vaccination plan.


  • Health care providers who are currently providing the COVID-19 vaccine will administer third doses to their patients.
  • Health care providers that are not able to provide vaccination must identify eligible patients and complete a referral form for the patient to bring to their vaccination appointment or walk-in at either the TBDHU CLE Coliseum clinic or, for those living in a District community, their local Family Health Team.

Patients must present a completed referral form, signed by their health care provider, at the time of vaccination. Without this form, a third dose will not be given. Please contact your health care provider to obtain a signed referral form. If you have any questions, please contact the TBDHU at 807-625-5900 or with any questions.

Last Updated: 16/09/2021