Statement from the Council of Chief Medical Officers of Health (CCMOH): COVID-19 Vaccination and the Use of COVID-19 Vaccine Boosters


We continue making great progress with COVID-19 vaccination across Canada with vaccinated individuals protecting themselves, their families and communities against severe COVID-19 outcomes and reducing the risk of virus transmission. Over 84% of the eligible population aged 12 years and older have now been vaccinated with two doses and we are seeing the positive impacts of vaccination in many parts of our country. The road ahead looks brighter than it did before, but we need to be mindful of the persistent risks posed by the highly transmissible Delta variant of concern. The majority of COVID-19 hospitalizations are amongst the unvaccinated, which is why as Chief Medical Officers of Health, we encourage everyone to get fully vaccinated as it remains our best defense against severe outcomes. We remain committed to implementing vaccine strategies that reflect the latest evidence and bring the greatest benefit to our populations.

Building on the progress we have made to date, at this stage of the pandemic, our efforts are focused on doing all we can to minimize serious illness and overall deaths while preserving health system capacity. We are also aiming to reduce COVID-19 transmission to protect key populations, including those at greatest risk. Every step of the way, our responses are balanced with the need to minimize the broader negative impacts of the pandemic on society. This includes impacts that have the potential to further strain our health systems and overall wellness now and into the future.

The benefits of vaccination to help us achieve these goals are clear. Evidence continues to show that being fully vaccinated provides strong protection, especially against severe illness, hospitalization and death from COVID-19, including against Delta and other variants of concern. Those with a strong immune response to their primary series will continue to be protected for some time. For some groups, their protection can decrease gradually over time, leaving them at higher risk for serious outcomes.

We continue to base our decision-making on scientific evidence and expert advice to guide the use of authorized COVID-19 vaccines. On October 29, 2021, the National Advisory Committee on Immunization (NACI) provided interim guidance on the use of a booster dose at least six months after receipt of a COVID-19 vaccine primary series. This provides longer protection against COVID-19. NACI recommends booster doses for some key populations, 6 months or more after a primary series of COVID-19 vaccines approved by Health Canada. The key populations recommended to receive boosters at this time are those at greatest risk of decreased protection over time, and greatest risk of severe illness and outcomes. This also includes some health care providers who received their initial vaccine series with less than 28 days between doses. These health professionals could pose an increased risk of transmission to vulnerable populations, and would leave a critical gap in our health systems should they become ill even with a mild infection.

Given there is currently no evidence of widespread waning of protection against severe disease in the general population who have been vaccinated against COVID-19 in Canada, boosters for this group are not required at this time but we will continue to monitor vaccine effectiveness and other data to inform the need in the future. NACI's current recommendations for key populations were informed by the current epidemiology in Canada and the latest evidence of vaccine effectiveness and potential decreased protection.

As Canada's Chief Medical Officers of Health, we thank NACI for their analysis and for providing recommendations based on current evidence to inform provincial/territorial and regional public health decisions on how COVID-19 booster vaccines are best used in vaccination programs at this time. Provinces and territories will use NACI's advice with some adjustments based on local epidemiology and unique circumstances, as appropriate.

It is important to remember that, while COVID-19 vaccines approved in Canada have been an important tool in our toolbox against this pandemic, vaccines are not 100% effective and cannot control COVID-19 on their own. Going into the winter months, we all need to continue with key public health strategies that have been effective in keeping this pandemic under control. In addition, we urge everyone living in Canada to protect themselves and others by following measures and the advice of the public health authority in their area. This includes staying home when sick, getting tested if you have symptoms, hand washing, masking, and getting influenza vaccination when and as soon as offered in your jurisdiction.

All of our collective efforts in the coming weeks and months will help us learn, adapt and keep Canada on the path to a brighter future where our populations are protected against severe outcomes; COVID-19 is manageable like many other viruses; and we can safely and fully enjoy the things we love most.

The Council of Chief Medical Officers of Health includes the Chief Medical Officer of Health from each provincial and territorial jurisdiction, Canada's Chief Public Health Officer, the Chief Medical Advisor of Health Canada, the Chief Medical Officer of Public Health of Indigenous Services Canada, the Chief Medical Officer from the First Nations Health Authority, and ex-officio members from other federal government departments.

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