COVID-19 vaccine update: Pfizer-BioNTech Comirnaty® recommended for individuals aged 18 to 24 years

Advisory Alert

October 1, 2021

*Cette information est seulement disponible en anglais.

To: Local Health System Partners


Guidance on the use of mRNA vaccines for those under 25 years of age

This Advisory Alert provides direction on the use of mRNA COVID-19 vaccines in adolescents aged 12 to 17 years and discusses the use of Moderna Spikevax® COVID-19 vaccine in individuals 18 to 24 years of age. This guidance comes subsequent to Health Canada’s expansion of authorization of the Moderna Spikevax® and new recommendations from the National Advisory Committee on Immunization (NACI).

Health Canada expands authorization of Moderna Spikevax® COVID-19 vaccine and NACI recommendations

On August 27, 2021, Health Canada expanded the interim authorization of Moderna  Spikevax® to include individuals 12 years of age and older. On the same day, the National Advisory Committee on Immunization (NACI) issued recommendations on the use of mRNA COVID-19 vaccines in adolescents 12 to 17 years of age. The NACI strongly recommend that a complete series with an mRNA COVID-19 vaccine be offered to adolescents 12 to 17 years of age who do not have contraindications to the vaccine, with informed consent as a requirement for all mRNA COVID-19 vaccines.

New Chief Medical Officer of Health direction: Pfizer-BioNTech Comirnaty® COVID-19 vaccine recommended for individuals under the age of 25

On September 29, 2021, the Chief Medical Officer of Health issued a statement on COVID-19 vaccines for individuals aged 18 to 24 years. Ontario is preferentially recommending the use of Pfizer-BioNTech Comirnaty® for individuals aged 18 to 24 years old effective immediately based on the current available analysis from Ontario’s adverse events following immunization (AEFI) surveillance system.

This recommendation was based on the advice of Ontario’s Children COVID-19 Vaccine Table, the Ontario Vaccine Clinical Advisory Group, and Public Health Ontario and is due to an observed increase in Ontario of pericarditis/myocarditis (Public Health Ontario, PDF) following vaccination with Moderna Spikevax® compared to Pfizer-BioNTech Comirnaty® in the 18 to 24 year old age group, particularly among males. The majority of reported cases have been mild with individuals recovering quickly, normally with anti-inflammatory medication. Symptoms have typically been reported to start within one week after vaccination, more commonly after the second dose. Canadian data indicates a higher number of myocarditis and/or pericarditis cases in younger age groups than would normally be expected, with preliminary analyses suggesting a higher unadjusted rate of myocarditis/pericarditis reported after vaccination with Moderna Spikevax® compared to Pfizer-BioNTech Comirnaty®. A detailed analysis can be found in Public Health Ontario’s enhanced epidemiological summary (PDF). For more information, please read the Ministry of Health’s statement.

Use of Moderna Spikevax® COVID-19 vaccine among individuals aged 18 to 24 years

While Health Canada has approved the Moderna Spikevax® for individuals under 25, starting immediately, the province of Ontario will use Pfizer-BioNTech Comirnaty® for youth aged 12 to 24 years. Anyone 18 to 24 who wishes to receive Moderna Spikevax® may continue to do so with informed consent. Vaccination is highly recommended; the benefits of vaccination outweigh the potential risks. The risk of contracting vaccine myocarditis and other serious adverse events including pericarditis, arrhythmia, deep-vein thrombosis, pulmonary embolism, myocardial infarction, intracranial hemorrhage, and thrombocytopenia is 18 times higher among patients with COVID-19.

To assist you in your discussions with patients, a summary of myocarditis/pericarditis after COVID-19 vaccination is provided in this factsheet (English, French).

For context, several COVID-19 vaccine program changes were made in Ontario beginning June 2021. These include an acceleration of second dose administration that was facilitated by increased Moderna Spikevax® supply, the increased use of mixed product schedules, an increase in the number of young adults and adolescents immunized, and a transition from a longer interval between first and second doses to shorter intervals such as those outlined in the vaccine product monographs (21 days for Pfizer-BioNTech Comirnaty® and 28 days for Moderna Spikevax®).

Reporting adverse events following immunization

All cases of myocarditis or pericarditis following vaccination should be reported to Public Health Sudbury & Districts:

For additional guidance on AEFI reporting, please visit Public Health Ontario for a reporting overview, or read a summary of all COVID-19 AEFIs in Ontario.

Additional information

COVID-19 vaccines continue to be recommended and are highly effective at preventing symptomatic infection and severe outcomes from COVID-19 disease, which is also associated with a risk of myocarditis.

For more information on the COVID-19 vaccines, visit our FAQ web page or call Public Health Sudbury & Districts at 705.522.9200 (toll-free 1.866.522.9200). Visit our Vaccination Clinics for COVID-19 page for information on clinic dates and locations. This page is updated frequently as new information becomes available.


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 October 1, 2021