COVID-19 vaccine update: Booster dose eligibility, new groups for a three-dose primary series, and booster dose timing following COVID-19 infection

Advisory Alert

February 9, 2021

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To: Local Health System Partners

FOR IMMEDIATE ATTENTION

New booster dose eligibility, updates to three-dose primary series, and recommendations for vaccination post COVID-19 infection

This Advisory Alert outlines guidance from the Ontario Ministry of Health regarding booster dose eligibility for select individuals 12 to 17 years of age, a three-dose primary vaccination series for immunocompromised children 5 to 11 years of age, and recommendations for booster dose vaccination intervals following COVID-19 infection. All updates are as outlined in the Ministry of Health COVID-19 Vaccine Third Dose Recommendations (PDF) guidance document (see attachment, link active following posting to Ministry website).

The newly expanded booster dose eligibility is issued in follow-up to the December 17, 2021, Advisory Alert on booster dose eligibility and the January 14, 2022, Advisory Alert on fourth doses for select populations. Updates to the extended (3 dose) primary series eligibility for those 5-11 years old follow the Advisory Alerts issued on September 16 and October 20, 2021. The recommendations for vaccination intervals post COVID-19 infection are in accordance with new guidance from the National Advisory Committee on Immunization (PDF, NACI).

Select individuals 12 to 17 years of age now eligible for booster doses

Effective immediately, select individuals 12 to 17 years of age are now eligible for a booster dose of the COVID-19 vaccine ≥ 3 months (84 days) after completion of their primary series.

Individuals 12 to 17 years of age are eligible for a booster dose of the COVID-19 vaccine if they have an underlying medical condition that may put them at high risk of severe illness due to COVID-19. These underlying health conditions include:

• Immunocompromised individuals and those who have already received a three‑dose primary series (in this case, a booster dose would be their fourth dose and the previous referral letter from a third dose for the primary series can be noted OR they may present proof of eligible prescriptions)
• Cancer— and undergoing active treatment
• Chronic kidney disease
• Chronic lung diseases, including uncontrolled asthma
• Cystic fibrosis
• Neurodevelopmental and other chronic neurological conditions including epilepsy and cerebrovascular disease
• Diabetes (type 1 & 2)
• Down syndrome
• Congenital heart disease or other chronic heart diseases, including pulmonary hypertension
• Chronic liver disease
• Obesity (BMI ≥30)
• Pregnancy
• Sickle cell disease or thalassemia
• Substance use disorders
• Medically fragile/having medically complex needs

First Nations, Inuit, and Métis individuals 12 to 17 years of age are also eligible for their booster dose of the COVID-19 vaccine.

The intent of the booster dose is to restore protection that may have decreased over time with the goal of enhancing immune response. Data on the effectiveness and safety of a booster dose in adolescents 12 to 17 years of age are currently limited. Preliminary safety data from the real-world use of boosters in adolescents showed no additional safety concerns beyond those noted from a primary series. Eligible individuals should consult their health care provider for guidance on specific timing of booster dose vaccination if they have questions. Individuals 12 to 29 years of age are preferentially recommended to receive Pfizer-BioNTech Comirnaty (30mcg) but may receive Moderna Spikevax (50mcg) with informed consent.

More information is available in the Ministry of Health COVID-19 Vaccine Third Dose Recommendations (PDF) (see attachment, link active following posting to Ministry website).

Three-dose primary vaccine series for immunocompromised children 5 to 11 years of age

In addition to first and second dose eligibility, a third dose of the mRNA COVID-19 vaccine is recommended for select individuals 5 to 11 years of age. The following groups are eligible for a third dose in their primary vaccination series:

• Individuals receiving dialysis (hemodialysis or peritoneal dialysis)
• Individuals receiving active treatment (for example, chemotherapy, targeted therapies, immunotherapy) for solid tumour or hematologic malignancies
• Recipients of solid-organ transplant and taking immunosuppressive therapy
• Recipients of chimeric antigen receptor (CAR)-T-cell therapy or hematopoietic stem cell transplant (within 2 years of transplantation or taking immunosuppression therapy)
• Individuals with moderate to severe primary immunodeficiency (for example, DiGeorge syndrome, Wiskott-Aldrich syndrome)
• Individuals with HIV with prior AIDS defining illness or prior CD4 count ≤ 200/mm3 or prior CD4 fraction ≤ 15% or (in children 5 to 11 years) perinatally acquired HIV infection
• Individuals receiving active treatment with the following categories of immunosuppressive therapies: anti-B cell therapies2 (monoclonal antibodies targeting CD19, CD20 and CD22), high-dose systemic corticosteroids (refer to the Canadian Immunization Guide for suggested definition of high dose steroids), alkylating agents, antimetabolites, or tumor-necrosis factor (TNF) inhibitors and other biologic agents that are significantly immunosuppressive

Note: Active treatment includes patients who have completed treatment within 3 months. Active treatment is defined as chemotherapy, targeted therapies, immunotherapy, and excludes individuals receiving therapy that does not suppress the immune system (for example, solely hormonal therapy or radiation therapy). Active treatment for patients receiving B-cell depleting therapy includes patients who have completed treatment within 12 months.

The recommended interval between the second dose and the third dose in the initial primary series is at least 2 months (56 days). As per NACI, the minimum interval is 28 days; however, an interval longer than the minimum of 28 days between doses is likely to result in a better immune response. Exact timing should be decided with the treating provider to optimize the immune response. In alignment with first and second doses, the pediatric Pfizer-BioNTech Comirnaty (10mcg) vaccine will be used for third doses in the primary vaccine series.

Additional guidance, including an alphabetized medication list, is outlined in the Ministry of Health COVID-19 Vaccine Third Dose Recommendations (PDF) (see attachment, link active following posting to Ministry website).

New recommended intervals for booster dose vaccination following COVID-19 infection

Per emerging evidence and recommendations from NACI, a longer interval between SARS‑CoV-2 infection and vaccination is associated with improved antibody responses to COVID-19 vaccines. As a result, eligible individuals 12 years of age and older, infected with COVID-19 after their primary series but before their booster dose, are now recommended to receive their booster dose 3 months after symptom onset or positive test result (if asymptomatic). Individuals may choose to receive a booster dose sooner than the 3‑month interval from infection if they provide informed consent and if they are asymptomatic and have completed their isolation. Additionally, NACI notes that should SARS-CoV-2 infection occur prior to completion or initiation of the primary vaccination series, it is recommended that individuals who are not considered moderately to severely immunocompromised, receive the vaccine 8 weeks after symptom onset or positive test (if asymptomatic). Individuals who are moderately to severely immunocompromised are recommended to receive the vaccine 4 to 8 weeks after symptom onset or positive test (if asymptomatic). Those who have a history of multisystem inflammatory syndrome in children (MIS-C) are recommended to receive the vaccine dose when clinical recovery has been achieved or ≥ 90 days since the onset of MIS-C, whichever is longer.

Previous infection can be defined in different ways based on jurisdictional policies and access to testing. The following is being used by PHSD:

• Confirmed by a molecular (e.g., PCR) or Health Canada-approved antigen detection‑based test; or
• Symptomatic disease compatible with COVID-19 AND household exposure to a confirmed COVID-19 case.

Recommendations are regularly re-examined and issued as new evidence becomes available. For more information on booster dose intervals, review the Ministry of Health COVID-19 Vaccine Third Dose Recommendations (PDF) (see attachment, link active following posting to Ministry website).

Local vaccination opportunities

Please visit our Vaccination clinics for COVID-19 webpage for information on clinic dates, times, and locations. Clients can attend a walk-in vaccination clinic or book an appointment online at covid-19.ontario.ca/book-vaccine or by calling 705.674.2299 (toll‑free: 1.800.708.2505), between 8 a.m. and 6 p.m., Monday to Friday. Clients can also contact a local participating pharmacy or primary care provider.

Sincerely,

Original signed by

Dr. Penny Sutcliffe
Medical Officer of Health and Chief Executive Officer

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This item was last modified on February 10, 2022