COVID-19 vaccine update: Certain immunocompromised individuals eligible for second booster and amendments to Ministry of Health’s vaccine administration guide

Advisory Alert

May 5, 2022

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To: Local Health System Partners


This advisory alert highlights updates to the Ministry of Health’s COVID-19 Vaccine Booster Recommendations as well as the COVID-19 Vaccine Administration guide. Included below is information pertaining to new criteria which allows specific moderately to severely immunocompromised individuals to receive their second booster dose, the suggested interval between a SARS-CoV-2 infection and the first or second booster dose of COVID-19 vaccine, recommendations on the use of the Moderna Spikevax vaccine in pediatric

populations, and a summary of the recently approved Medicago COVIFENZ COVID-19 vaccine.

Eligibility to receive second booster dose (i.e., fifth dose) for specific moderately to severely immunocompromised individuals

Provincial guidance has been updated to note that individuals who are eligible for a second booster dose may receive this booster regardless of whether their primary series was a two-dose or three-dose primary series. This means that the second booster dose for immunocompromised individuals will be their fifth dose.

Specifically, moderately to severely immunocompromised are now eligible to receive a second booster (a fifth dose) of the COVID-19 vaccine if they are a member of one or more of the following groups:

The term “second booster dose” refers to the dose given after the complete primary series and first booster dose and it is recommended that the second booster (in this case the 5th dose) be offered five months (140 days) after receipt of the first booster. The minimum interval for the second booster is 3 months (84 days) after the first booster. For more information, review the Ministry of Health’s updated COVID-19 Vaccine Booster Recommendations (PDF).

Please note that eligible individuals can book their second booster (fifth dose) with a Public Health led clinic by calling (NEW) 705.522.9200 (toll-free: 1.866.522.9200). The call centre is open Monday to Friday between 8:30 a.m. and 4:30 p.m. and is closed on statutory holidays. Booking online through the provincial portal is not yet available.

Alternatively, clients can present to a Public Health led clinic as a walk-in. Clients can also seek opportunities for vaccination through participating primary care providers or local pharmacies.

Interval between SARS-CoV-2 infection and booster doses

Individuals infected with SARS-CoV-2 after their primary series, but before their first and/or second booster dose, are recommended to receive their first or second booster 3 months (84 days) after symptom onset or a positive test (if asymptomatic). Of note, for individuals aged 12 to 17 years old, the interval of at least 6 months (168 days) should have also passed after completing the primary series before they receive their booster dose. This is in alignment with the National Advisory Committee on Immunization (NACI)’s recommended interval between the primary series and booster dose for this age group.

For a detailed summary of all suggested intervals between previous SARS-CoV-2 infection and COVD-19 vaccinations, please review the table on page 10 of the Ministry’s Guide for COVID-19 Vaccine Administration

Update: Moderna Spikevax for use in individuals aged 6 to 11

In accordance with the COVID-19 Vaccine Third Dose and Booster Recommendations, chapter two of the COVID-19 Vaccine Administration guide was updated with information pertaining to the use of the Moderna Spikevax vaccine in children aged 6 to 11 year. Please note, in alignment with NACI’s direction, the Ministry of Health has made a preferential recommendation for the use of Pfizer-BioNTech COVID-19 vaccine for individuals 5 to 29 years of age. The risk of myocarditis or pericarditis with Moderna Spikevax in children 6 to 11 years of age is unknown, though the risk observed in young adults was higher with Moderna Spikevax than Pfizer-BioNTech Comirnaty.

Medicago COVID-19 vaccine

The Medicago COVID-19 vaccine is the first adjuvanted vaccine approved for use by Health Canada as a primary series. It is a plant-based vaccine that can be administered to those aged 18 to 64. To date, clinical trail data shows that Medicago is effective in preventing confirmed symptomatic COVID-19 disease in the short term. The duration of protection is not yet known, and there is no data pertaining to its effectiveness against the Omicron variant. A primary series of the Medicago vaccine is currently considered to be two doses. Individuals can receive two doses of Medicago or as part of a mixed COVID-19 vaccine series with informed consent. At this time, Medicago is not authorized for use as a booster dose. Please note, that the Medicago vaccine is not yet available in Ontario. Stay tuned to future Advisory Alerts for information about local supply.

The safety and efficacy of Medicago has not yet been established in the following populations:

individuals who have an autoimmune condition

NACI continues to preferentially recommend the use of mRNA COVID-19 vaccines for most people due to the excellent protection they provide against severe illness and hospitalization, and their well-known safety profiles. The Medicago vaccine is a new option for individuals that are not able to or are unwilling to receive an mRNA vaccine. For more information on this vaccine, review the Medicago product monograph(Medicago Inc., PDF).

Local vaccination opportunities

Visit our Vaccination clinics for COVID-19 webpage for information on clinic dates, times, and locations. Eligible clients can attend a walk-in vaccination clinic or book an appointment online at or by calling 705.522.9200 (toll‑free 1.866.522.9200), between 8 a.m. and 6 p.m., Monday to Friday. Clients can also contact a local participating pharmacy, primary care provider, or health centre. Please refer to the section above for a special booking notice pertaining to those moderately to severely immunocompromised who are eligible for their second booster (5th dose).


Original Signed By

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

NOTE: All Advisory Alerts are found on our website.

This item was last modified on May 5, 2022