COVID-19 vaccine strongly recommended for high-risk populations

Advisory Alert

April 8, 2022

*Cette information est seulement disponible en anglais.

To: Local Health System Partners


This Advisory Alert serves to reinforce the importance of COVID-19 vaccination across all populations, especially those who are high-risk, including those who are pregnant and those who are moderately to severely immunocompromised. Also outlined within this Alert is the Quick Reference Tool: COVID-19 Vaccine Minimal Contact Intervention (PDF), which supports health care providers as they navigate the COVID-19 decision making process with their patients.

COVID-19 vaccination during pregnancy

Despite  the National Advisory Committee on Immunization (NACI), the Government of Ontario (PDF), and the Society of Obstetricians and Gynaecologists of Canada, ( PDF), recommending first, second, third (if applicable) and booster doses of the COVID-19 during pregnancy, provincially we continue to observe lower rates of vaccination in this population. It has been shown that individuals who contract COVID-19 during pregnancy are more likely to experience severe outcomes, be admitted to hospital and require critical care than their age-matched peers. The risk of morbidity due to COVID-19 is higher amongst those who are pregnant.

Vaccination against the COVID-19 virus, is safe and effective during pregnancy. It is imperative that pregnant persons are prioritized to receive a COVID-19 vaccine and additional support should be provided to pregnant individuals to ensure an informed choice about their vaccination status.  To support evidence-informed choices about the COVID-19 vaccine, SickKids Vaccine Consult Service is now serving pregnant and breastfeeding individuals in partnership with the VaxFacts Clinic at Scarborough Health Network (SHN). The SickKids COVID-19 Vaccine Consult Service is a by-appointment phone service that provides a safe, judgement free space to have an open conversation about the COVID-19 vaccine for children, youth, pregnancy and breastfeeding. Clients interested in booking a consultation can visit COVID-19 Vaccine Consult Service (

COVID-19 vaccine for moderately to severely immunocompromised individuals

As outlined in the Ministry of Health COVID-19 Vaccine Third Dose and Booster Recommendations (PDF), those who are moderately to severely immunocompromised are at increased risk of severe outcomes from COVID-19. Individuals in this population have also been shown to produce either a sub-optimal immune response or no response to a complete two-dose primary vaccine series. Therefore, it is of the utmost importance that those who are eligible do receive a third dose (completing a three-dose primary series), and subsequently a fourth dose (booster) to ensure the best protection against the virus.

The three-dose primary series should be offered to those aged 5 and older who meet any of the following criteria:

The third dose to complete the primary series is recommended to be administered 2 months (56 days) after receipt of the second dose.

Moderately to severely immunocompromised individuals aged 5 to 11 years are also recommended to receive a three-dose primary series. Eligible individuals aged 5 to 11 years should be given the pediatric Pfizer-BioNTech Comirnaty (10 mcg). However, consideration for use of the Moderna Spikevax (50 mcg) vaccine may be provided for moderately to severely immunocompromised individuals ages 6 to 11 years. More information on fourth dose eligibility in this population can be reviewed in the Ministry of Health’s COVID-19 Vaccine Third Dose and Booster Recommendations (PDF) and the Advisory Alert published January 7, 2022.

Individuals aged 12 years and older who are moderately to severely immunocompromised should be encouraged to receive a fourth dose (booster) 3 months (84 days) after the three-dose primary series has been completed. If presenting to a Public Health clinic or pharmacy, eligible individuals should provide proof of prescription or a completed referral form (English (PDF)). Third and fourth doses may also be received at participating primary care provider offices or specialty programs.

Quick Reference Tool: COVID-19 Vaccine Minimal Contact Intervention

As a trusted source of information in our communities, we are asking local health system partners to continue the discussion about COVID-19 vaccination with patients, particularly those in the groups outlined above. The Quick Reference Tool: COVID-19 Vaccine Minimal Contact Intervention (PDF) provides a user‑friendly format for engaging your patients in discussions around topics such as the safety, effectiveness and importance of the COVID-19 vaccine, vaccination opportunities, along with information dispelling common misconceptions. Specifics to address inquiries about COVID-19 vaccines and pregnancy as well as the immunocompromised are also included within.

Local Vaccination Opportunities

Using a multi-layered approach, including continuing to wear a well-fitted mask in indoor public settings, practising physical distancing, daily symptom screening, staying home when ill and staying up to date with all recommended COVID-19 vaccinations, remains most important to protect our community against COVID-19 and the impacts of future waves.

Please remind your patients that it is not too late to get their first, second, third (if applicable) and booster doses as soon as they become eligible.  It remains important for everyone to complete their primary series if they have not already and get boosted as soon as possible. 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 or by calling 705.522.9200 (toll‑free: 1.866.522.9200), between 8:30 a.m. and 4:30 p.m., Monday to Friday. Clients can also contact a local participating pharmacy, primary care provider or health centre.


Original Signed By

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

Please note that email addresses of some recipients were provided to Public Health Sudbury & Districts by the College of Physicians and Surgeons of Ontario (CPSO) for the purpose of communications related to COVID-19. If you prefer to no longer receive Advisory Alerts from Public Health, please reply to this email requesting to be removed from our distribution list.

NOTE: All Advisory Alerts are found on our website.

This item was last modified on April 11, 2022