Updated guidance on the use of the protein subunit XBB.1.5 COVID-19 vaccine

The National Advisory Committee on Immunization (NACI) has issued updated guidance on the use of Nuvaxovid XBB.1.5 COVID-19 vaccine manufactured by Novavax. NACI notes that based on the number of doses administered, there is much greater experience with mRNA COVID-19 vaccines (Comirnaty–Pfizer/BioNTech and Spikevax–Moderna). However, clinical evidence with the original Nuvaxovid COVID-19 vaccine has demonstrated that it has a good safety profile and was immunogenic and effective against original SARS-CoV-2.1 With the Novavax Nuvaxovid COVID-19 vaccine being updated to target XBB.1.5, the marketed mRNA and protein subunit COVID-19 vaccines now target the same strain. As a result, NACI states that either type of vaccine can be used. Previously, Nuvaxovid was recommended only for those who were unwilling or unable to receive an mRNA vaccine.1Current NACI recommendations:1. Individuals being vaccinated against COVID-19 should receive the most recently updated COVID-19 vaccine according to the authorized age group. (Strong NACI Recommendation)An mRNA or protein subunit COVID-19 vaccine can be used in unvaccinated or previously vaccinated individuals who do not have contraindications to the vaccine.mRNA COVID-19 XBB.1.5 vaccines are authorized for age six months of age or olderNuvaxovid XBB.1.5 is authorized for age 12 years of age or older.1 2. For unvaccinated individuals 12 years of age or older receiving Nuvaxovid XBB.1.5 as a primary series, the authorized schedule is two doses.1,2 However, unvaccinated individuals who are not immunocompromised may receive a one-dose schedule. (Discretionary NACI Recommendation)1If receiving two doses in a primary series, NACI recommends an interval of eight weeks between doses for those who are not immunocompromised, and four to eight weeks for those who are moderately to severely immunocompromised.1Background to recommendation: The European Medicines Agency has approved a one-dose schedule for unvaccinated individuals receiving Nuvaxovid XBB.1.5, while a two-dose primary series schedule is approved by Health Canada and the US Food and Drug Administration. This may lead Canadian healthcare providers to recommend a one-dose schedule for Nuvaxovid XBB.1.5 (off-label) for previously unvaccinated individuals who are not immunocompromised in Canada. A one-dose schedule for Nuvaxovid XBB.1.5 in non-immunocompromised unvaccinated individuals would align with the dosage schedules for mRNA XBB.1.5 COVID-19 vaccine schedules for unvaccinated individuals (i.e., 1 dose for non-immunocompromised individuals 5 years of age or older), which would contribute to more streamlined COVID-19 vaccination recommendations in Canada. The risk of myocarditis and/or pericarditis from COVID-19 vaccines is also expected to be lower with a one-dose schedule, compared to a two-dose schedule.1 3. Unvaccinated individuals 12 years of age or older who are moderately to severely immunocompromised and wish to receive Nuvaxovid XBB.1.5 should be given aminimum of two doses. New recipients of hematopoietic stem cell transplantation (HSCT) and chimeric antigen receptor (CAR) T cell therapy should receive three doses.(Strong NACI recommendation)1Refer to the “Immunization of immunocompromised persons” chapter of the CanadianImmunization Guide for additional details regarding vaccine schedules for moderatelyto severely immunocompromised individuals. Moderately to severely immunocompromising conditions and relevant considerations for COVID-19 immunization are available in the COVID-19 chapter of the Canadian Immunization Guide.3 The NACI update includes a summary table that compares the various aspects of protein subunit and mRNA COVID-19 vaccines.1References:1. National Advisory Committee on Immunization (NACI). An Advisory Committee Statement (ACS). Updated guidance on the use of protein subunit COVID-19 vaccine (Novavax Nuvaxovid). March 8, 2024. (accessed March 12, 2024).2. Novavax, Inc. Nuvaxovid XBB.1.5 COVID-19 vaccine (recombinant protein, adjuvanted) product monograph. Gaithersburg, MD; December 5, 2023. (accessed March 12, 2024).3. Government of Canada. COVID-19 vaccines: Canadian Immunization Guide. (accessed March 12, 2024).

Updated guidance on the use of the protein subunit XBB.1.5 COVID-19 vaccine

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