Summary of NACI statement of October 27, 2023: Updated guidance on the use of COVID-19 vaccines in individuals who have not previously been vaccinated against COVID-19

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• Overview
• What you need to know
• Quotes

Overview

• On October 27, 2023, the Public Health Agency of Canada (PHAC) released the National Advisory Committee on Immunization's (NACI) Updated guidance on the use of COVID-19 vaccines in individuals who have not previously been vaccinated against COVID-19. This guidance is based on current evidence and NACI expert opinion.
• On September 12 and 28, 2023, Health Canada authorized XBB.1.5-containing mRNA COVID-19 vaccine products (Moderna Spikevax 1.5 and Pfizer-BioNTech Comirnaty Omicron XBB.1.5 respectively) for use in individuals 6 months of age and older.
• The updated COVID-19 vaccines have been authorized for those who have never previously received a COVID-19 vaccine (also referred to as a "primary series") and those previously vaccinated with COVID-19 vaccines.
• As a result of the evolving landscape in Canada, with a significant portion of the population having either received COVID-19 vaccinations or developed immunity through prior exposure to SARS-CoV-2, there is a need to adapt vaccination strategies and schedules to align with the changing circumstances.

Updated guidance

Going forward, XBB.1.5 vaccines are the recommended products for those previously unvaccinated and previously vaccinated.

For primary series COVID-19 vaccine in those who were not previously vaccinated, NACI recommends that:

• Children 6 months to under 5 years of age who are at high risk for severe illness due to COVID-19 should be vaccinated against COVID-19, and other children in this age group may be vaccinated;
• Those 5 years of age and over should be vaccinated against COVID-19.
• For those previously not vaccinated, NACI's recommended schedule is outlined in the latest NACI Statement and summarized as follows:
  • For those who are 6 months to under 5 years of age, 2 doses of Moderna Spikevax XBB.1.5 or 3 doses of Pfizer-BioNTech Comirnaty Omicron XBB.1.5, with an 8-week interval between doses are recommended. For those who are moderately to severely immunocompromised, an additional dose is recommended with an interval of 4 to 8 weeks between each dose (with a preference for Moderna Spikevax XBB.1.5, as it is more feasible to offer 3 doses of this product compared to 4 doses of Pfizer-BioNTech Comirnaty Omicron XBB.1.5).
  • For those who are 5 years of age over, 1 dose of Moderna Spikevax XBB.1.5 or Pfizer-BioNTech Comirnaty Omicron XBB.1.5 is recommended. For those who are moderately to severely immunocompromised, an additional dose is recommended with an interval of 4 to 8 weeks between the 2 doses.
  • There is no longer a product preference between Moderna Spikevax and Pfizer-BioNTech Comirnaty when XBB.1.5 vaccines are offered to unvaccinated individuals 12 to 29 years of age.

For those previously vaccinated but who did not receive an XBB.1.5 vaccine, a dose of XBB.1.5 is recommended 6 months following previous vaccination or SARS-CoV-2 infection (whichever is later). Shorter intervals (i.e., 3 months to less than 6 months) following previous vaccination or infection have also not been shown to pose a safety risk.

The NACI Statement also provides guidance for those who started a primary series with earlier (non-XBB.1.5) COVID-19 vaccines but did not complete the series.

NACI will continue to monitor the evolving evidence and will update guidance as needed.

For the full Statement, including supporting evidence and rationale, as well as comprehensive dosing schedules, please see NACI's Updated guidance on the use of COVID-19 vaccines in individuals who have not previously been vaccinated against COVID-19.

What you need to know

• COVID-19 vaccine formulations that target the XBB.1.5 sub-lineage of the virus are now available in Canada. Good immune responses against related XBB strains have been observed in studies.
• The COVID-19 situation in Canada and around the world continues to evolve, and we now see very high rates of previous infection in older children, adolescents, and adults. Because most older children, adolescents and adults have been previously infected, only 1 dose of vaccine is recommended for people 5 years and older when starting the COVID-19 vaccine series for the first time, if they are not immunocompromised. Previously unvaccinated younger children and people who are moderately to severely immunocompromised will continue to receive more than one dose in the primary series.
• The previous product preference for Pfizer-BioNTech Comirnaty for those not previously vaccinated between the ages of 12 and 29 years has been removed. This is because the risk of myocarditis and/or pericarditis is expected to be lower for most individuals with the XBB.1.5 vaccine due to the use of a 1-dose schedule in most individuals; and potentially due to a lower dosage of the available Moderna XBB.1.5 vaccine compared to the original Moderna Spikevax vaccine (see the NACI statement for additional details).
• For those previously unvaccinated, vaccination with the XBB1.5-containing vaccine is recommended for all those 5 years of age and over, and also for those 6 months to less than 5 years of age who are at high risk of severe illness due to COVID-19. It may be offered for other children 6 months to less than 5 years of age. For those previously vaccinated, COVID-19 vaccine is recommended for the above groups and is particularly important for those at increased risk of SARS-CoV-2 infection or severe COVID-19 disease, for example:
  • Adults 65 years of age or older;
  • Residents of long-term care homes and other congregate living settings;
  • Individuals with underlying medical conditions that place them at higher risk of severe COVID-19;
  • Individuals who are pregnant;
  • Individuals in or from First Nations, Métis and Inuit communities;
  • Members of racialized and other equity-deserving communities;
  • People who provide essential community services.
• Getting an XBB.1.5-containing vaccine this fall is expected to enhance individual protection against severe outcomes from COVID-19 during the respiratory virus season.
• A submission for an updated Novavax Nuvaxovid vaccine which contains XBB.1.5 is currently being reviewed by Health Canada. NACI will review the use of the Novavax Nuvaxovid vaccine in light of the updated recommendations for individuals who have never received a COVID-19 vaccine when more information becomes available.

For more information on NACI's recommendations on the use of COVID-19 vaccines, please refer to the COVID-19 vaccine chapter in the Canadian Immunization Guide (CIG), as well as additional statements on the NACI web page.

Quotes

"The COVID-19 vaccine schedule has become more complex for Canadians over time, as more vaccines and boosters have been approved. Following the authorization of the XBB.1.5 COVID-19 vaccines, NACI has worked to simplify the guidance for those who have not been previously vaccinated, including all age groups and for those with and without immunocompromising conditions. Most people 5 years of age and over need only one dose of XBB.1.5 COVID-19 vaccine this fall, regardless of whether or not they have been previously vaccinated. NACI continues to encourage Canadians to receive a dose of XBB.1.5 this fall to help protect themselves against the most prevalent strains. This is especially important for those most at risk of severe illness. NACI's recommendations are grounded in the best available scientific evidence. We will keep monitoring the situation and update our guidance accordingly."

"I want to express my gratitude to NACI for their updated guidance on COVID-19 vaccination. NACI has simplified its recommendations on providing COVID-19 vaccines to anyone 6 months or older who has not previously been vaccinated against COVID-19. One dose of the updated XBB.1.5 vaccine is recommended for most people 5 years of age and older who are previously unvaccinated. As we enter the fall and winter seasons, protection against SARS-CoV-2 and other respiratory viruses can be increased by getting vaccinated along with the use of personal protective measures."