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Ontario's Vaccine Clinical Advisory Group recommends some cohorts receive third mRNA vaccine


Ontario's Vaccine Clinical Advisory Group has updated its recommendations for specific populations regarding who should receive a third or booster mRNA Pfizer-BioNTech or Moderna COVID-19 vaccine. 

"Achieving high first and second dose coverage remain the focus of the Ontario’s COVID-19 vaccination program," read a release from the group. "However, for some populations, a third dose may be required as two doses may not provide sufficient protection."

The following severely immunocompromised patients should receive a third dose at least two months after their second, with the exact timing decided with the treatment provider:

  • Transplants recipients (including solid organ transplant and hematopoietic stem cell transplants);
  • Those being treated with an anti-CD20 agent (e.g. rituximab, ocrelizumab, ofatumumab), commonly used for conditions such as multiple sclerosis, rheumatoid arthritis, leukemias/lymphoma etc.
  • Those getting active treatment (chemotherapy, targeted therapies, immunotherapy) for malignant hematologic disorders (e.g. Acute myeloid leukemia, chronic myeloid leukemia, acute lymphoblastic leukemia, chronic lymphocytic leukemia).

The vulnerable elderly in high-risk congregate settings should also receive a third dose, due to the risks of the Delta variant of concern "particularly in the context of emerging literature on the reduced immune response and the more rapid waning of antibody responses in this population."

The recommendation specifies residents of Long-Term Care Homes, High-Risk Retirement Homes and Elder Care Lodges should get a third shot at least five months after their second dose. 


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