Remarks from the Chief Public Health Officer on December 3, 2021


December 3, 2021 | Ottawa, ON | Public Health Agency of Canada

The COVID-19 pandemic continues to create stress and anxiety for many Canadians, particularly those who do not have ready access to their regular support networks. Through the Wellness Together Canada online portal, people of all ages across the country can access immediate, free and confidential mental health and substance use supports, 24 hours a day, seven days a week.

Nationally, daily case counts continue to increase, but there is still considerable regional variation in disease activity. Over the most recent 7-day period, an average of over 2,800 new cases were reported daily across Canada. Currently, severe illness trends have levelled off, but are still elevated and could begin to rise again unless we can keep infection rates down. Over the past week, on average 1,540 people with COVID-19 were being treated in our hospitals each day, including 465 in intensive care --and 19 deaths were reported daily.

The emergence and spread of the Omicron variant of concern, including 11 recent detections in travellers coming into Canada and/or their close contacts, is yet another reminder of how quickly things can shift in this pandemic, unless we continue to reduce the spread and impact of the virus with vaccination and other layers of protection. In addition to strengthening diagnostics, therapeutics, infection prevention and control, vaccine uptake and other response aspects --experts on Canada's National Advisory Committee on Immunization or NACI have continued to update guidance to help strengthen our COVID-19 vaccination programs. Today, NACI updated advice on COVID-19 mRNA vaccine booster doses, as well as recommendations on the use of mRNA COVID-19 vaccines in adolescents and young adults.

NACI recommends -- and health authorities in Canada agree -- that immunization in those who are eligible, but have yet to receive their primary series, should continue to remain the top priority in Canada and around the world. NACI has reaffirmed that the benefits of receiving an mRNA COVID-19 vaccine continue to outweigh any potential risks of experiencing rare side effects following vaccination with an mRNA vaccine, including the rare risk of vaccine-associated myocarditis and/or pericarditis most often seen in males aged 12 to 29 years.

Regarding boosters, NACI considered emerging evidence on waning protection of vaccines over time and the safety and potential benefits of mRNA vaccine booster doses. In the context of the Delta variant, evidence suggests that vaccine effectiveness against infection and symptomatic disease decreases with time, and possibly against severe illness as well, especially in older individuals. No additional safety concerns were noted following mRNA vaccine booster doses. The rare risk of myocarditis and/or pericarditis appears to be lower after the booster dose than after the second dose of the primary series --though is higher than after the first dose. Based on this, NACI has increased the strength of their recommendations to now say --a booster dose of an authorized mRNA COVID-19 vaccine should be offered 6 months or more after completion of a primary COVID-19 vaccine series to:

  • People aged 50 years or older
  • Adults living in seniors' long-term care or other congregate living settings that provide care for seniors
  • People who received an exclusively viral vector COVID-19 vaccine series, consisting of only AstraZeneca/COVISHIELD and/or the Janssen COVID-19 vaccine
  • Adults in or from First Nations, Inuit and M├ętis communities
  • Frontline healthcare workers having direct close physical contact with patients

NACI further recommends that a booster dose of an authorized mRNA COVID-19 vaccine may be offered 6 months or more after completion of a primary COVID-19 vaccine series to adults aged 18-49 years, with consideration of jurisdictional and individual risks.

Finally, with respect to vaccination of adolescents and young adults, NACI considered new Canadian and international data that suggests the rare risk of myocarditis after receiving an mRNA COVID-19 vaccine may be lower with the Pfizer-BioNTech Comirnaty 30 microgram vaccine as compared to the Moderna Spikevax 100 microgram vaccine. These data also show that a longer interval between the first and second dose in the primary vaccination series results in stronger immune response and higher vaccine effectiveness -and-- that longer intervals may also be associated with a lower risk of myocarditis and/or pericarditis.

Accordingly, for adolescents and young adults aged 12 to 29 years, NACI now recommends that the use of Pfizer-BioNTech Comirnaty vaccine is preferred over the use of the Moderna Spikevax vaccine to start or complete a primary vaccine series. NACI further recommends that the second dose of a primary mRNA COVID-19 vaccine series should be provided 8 weeks after the first dose.

Now and during the winter months, while the virus continues to circulate worldwide and the significance and impact of the Omicron variant of concern is being assessed, the need for heightened vigilance remains. Regardless of which variant is circulating, we are better protected individually and collectively when we all do our best to maintain layers of protection by completing the COVID-19 primary vaccine series and getting a booster dose as recommended, wearing a quality snug-fitting mask, avoiding crowding and taking other measures as possible.

Read my backgrounder to access COVID-19 Information and Resources, including information on vaccination and ways to reduce your risk of infection and spreading the virus to others.


Media Relations
Public Health Agency of Canada

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