Updated COVID-19 vaccine recommendations for unvaccinated individuals

The National Advisory Committee on Immunization (NACI) has updated its guidance on the use of COVID-19 vaccines for individuals who have not previously been vaccinated against COVID-19. The updated guidance follows Health Canada’s authorization of XBB.1.5-containing mRNA COVID19 vaccine products (Moderna Spikevax XBB.1.5 and Pfizer-BioNTech Comirnaty Omicron XBB.1.5) in September, 2023. These vaccines are authorized for use in individuals six months of age or older who have never previously received a COVID-19 vaccine and for those who have previously been vaccinated with any COVID-19 vaccine(s). Recommendations: Previously unvaccinated individuals five years of age or older: These individuals should be vaccinated with a monovalent COVID-19 XBB.1.5 vaccine product from Moderna or Pfizer-BioNTech. (Strong NACI Recommendation) One dose is recommended (as per the authorized dosage schedule in the product monograph). An additional dose (given 4–8 weeks apart) is recommended for individuals who are moderately to severely immunocompromised. NACI no longer has a product preference between Moderna Spikevax and PfizerBioNTech Comirnaty when using XBB.1.5-containing COVID-19 vaccines for unvaccinated individuals 12–29 years of age. Compared to the original monovalent primary series, the risk of myocarditis and/or pericarditis is expected to be lower due to the single-dose schedule in most individuals and potentially because of the lower dosage of the available Moderna Spikevax vaccine (50 µg in the XBB.1.5 formulation compared to 100 µg in the original monovalent formulation). However, all vaccine recipients should still be informed and counselled on the rare risk of myocarditis and/or pericarditis following COVID-19 vaccination, regardless of the product received. Note that individuals five years of age or older who started a primary series with earlier formulations (i.e., original monovalent, original+BA.1 bivalent or original+BA.4/5 bivalent) but did not complete the series are recommended to complete the series with an XBB.1.5-containing vaccine. They should receive a total of two COVID-19 vaccine doses in the primary series if not immunocompromised, and three doses in the primary series if they are moderately to severely immunocompromised. Previously unvaccinated children six months to under five years of age: Children in this group who are at high risk of severe illness due to COVID-19 should be vaccinated with a monovalent COVID-19 XBB.1.5 vaccine product from Moderna or Pfizer-BioNTech. (Strong NACI Recommendation) Children in this group who are not known to be at high risk of severe illness due to COVID-19 may be vaccinated with a monovalent COVID-19 XBB.1.5 vaccine product from Moderna or Pfizer-BioNTech. (Discretionary NACI Recommendation) Risk factors for severe illness due to COVID-19 may include children who are medically fragile/have medical complexities, children with more than one comorbidity, children with neurological disorders, children with chronic lung disease, and children with Down syndrome (Trisomy 21), and other immunocompromising conditions. Two doses of Moderna Spikevax or three doses of Pfizer-BioNTech Comirnaty are recommended, with an 8-week interval between doses. An additional dose is recommended for individuals who are moderately to severely immunocompromised. A mixed product schedule using vaccines from different manufacturers can be offered for the primary series; however, if both Pfizer-BioNTech Comirnaty and Moderna Spikevax vaccine products are used in the same primary series for an individual six months to under five years of age, the total number of doses in the series should follow the Pfizer-BioNTech Comirnaty schedule. Note that children six months to under five years of age who started the primary series with a nonXBB.1.5 vaccine but did not complete the series should complete the primary series with an XBB.1.5-containing vaccine. Children who started the primary series at less than five years of age and turn five years of age before completing the series, should receive the number of XBB.1.5 vaccine doses recommended for those five years of age or older and use the age-appropriate dosage for their current age. Previously unvaccinated individuals five years of age or older who are moderately to severely immunocompromised: These individuals are recommended to receive two doses of COVID-19 vaccine, with a four- to eight-week interval between doses. Note that if the primary series was started with non-XBB1.5 COVID-19 vaccine(s) but the series was not completed, those five years of age or older who are moderately to severely immunocompromised should to receive a total of three doses of COVID-19 vaccines for the primary series. Previously unvaccinated individuals six months of age or older who are moderately to severely immunocompromised: These individuals should receive an additional dose of COVID-19 vaccine above the number of doses recommended for those who are not immunocompromised. (Strong NACI Recommendation) Individuals six months to under five years of age who are moderately to severely immunocompromised should receive three doses of Moderna Spikevax (preferred) or four doses of Pfizer-BioNTech Comirnaty, with a four- to eight-week interval between doses. The Moderna vaccine is preferred over the Pfizer-BioNTech vaccine because there are fewer doses in the Moderna Spikevax schedule, which will likely increase acceptability and make implementation easier. The updated NACI document includes three handy tables that can be bookmarked or printed and posted: Summary of available XBB.1.5-containing mRNA COVID-19 products by age (with dosage/volume, description–cap/label colour, dilution, doses/vial) Immunization schedule for previously unvaccinated individuals by age starting their vaccinations with XBB.1.5-containing mRNA COVID-19 vaccines Summary of number of recommended XBB.1.5-containing mRNA COVID-19 vaccine doses based on previous non-XBB.1.5 vaccination history (i.e., previously received original monovalent or original+BA.1 bivalent or original+BA.4/5 bivalent vaccines [non-XBB.1.5]). For individuals who have previously been vaccinated with a complete primary series that did not include an XBB.1.5-containing COVID-19 vaccine, one dose of XBB.1.5-containing COVID-19 vaccine is recommended six months following previous COVID-19 vaccination or SARS-CoV-2 infection (whichever is later). Shorter intervals (i.e., 3 months to < 6 months) following previous vaccination or infection have not been shown to pose a safety risk. Reference 1. National Advisory Committee on Immunization (NACI). Updated guidance on the use of COVID-19 vaccines in individuals who have not previously been vaccinated against COVID-19. October 27, 2023. (accessed October 31, 2023).

Updated COVID-19 vaccine recommendations for unvaccinated individuals

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