Pfizer bivalent COVID-19 vaccine now approved for primary immunization

Health Canada has approved Pfizer/BioNTech’s Comirnaty Original and Omicron BA.4/BA.5 COVID-19 vaccine for use in a primary vaccination series for individuals five years of age or older. Previously, the vaccine was only indicated for use as a bivalent booster. Health Canada issued the new marketing authorization with Terms and Conditions that need to be met by the manufacturer to establish the continued quality, safety and effectiveness of the vaccine.1 The manufacturer recommends a two-dose primary vaccination course: 0.3 mL (grey vial cap; do not dilute) given intramuscularly three weeks apart for individuals 12 years of age or older, and 0.2 mL (orange vial cap; dilute before use) three weeks apart for individuals aged five years to < 12 years.1 Note that the three-week dosing interval recommended by the manufacturer differs from the eight-week interval recommended by the National Advisory Committee on Immunization (see below). Pfizer/BioNTech’s Comirnaty Original and Omicron BA.4/BA.5 COVID-19 vaccine is the first bivalent mRNA vaccine to receive Health Canada authorization for use in a primary immunization series. Moderna’s Spikevax Bivalent Original/Omicron BA.4/5 (elasomeran/davesomeran mRNA COVID-19 vaccine) is under consideration by Health Canada for use in a primary immunization series in individuals six months to 11 years of age.2 On June 9, 2023, the National Advisory Committee on Immunization (NACI) released interim guidance on the (off-label) use of bivalent Omicron-containing mRNA COVID-19 vaccines for the primary vaccination series in children six months of age or older. In that document, NACI recommends the following primary immunization regimens: Children six months to four years of age: Moderna Spikevax bivalent BA.1 or BA.4/5 25 µg—two (0.25 mL) doses given at least eight weeks apart. It is not feasible to administer Pfizer-BioNTech Comirnaty bivalent BA.4/5 (3 µg) with the products that are currently available in Canada. Children five to 11 years of age: Pfizer-BioNTech Comirnaty bivalent BA.4/5 10 µg (0.2 mL) OR Moderna Spikevax bivalent BA.1 or BA.4/5 25 µg (0.25 mL)—two doses given at least eight weeks apart. Individuals 12 years of age or older: Pfizer-BioNTech Comirnaty bivalent BA.4/5 30 µg (0.3 mL) OR Moderna Spikevax bivalent BA.1 or BA.4/5 50 µg (0.5 mL)—two doses given eight weeks apart. The Pfizer vaccine is preferred for those 12–29 years of age, due to a lower risk of myocarditis and/or pericarditis. Individuals who are moderately to severely immunocompromised should receive a three-dose primary immunization series, with the doses described above for the various age groups given four to eight weeks apart.3 NACI notes that if a primary series is started with an original mRNA vaccine, a bivalent Omicron-containing vaccine can be used to complete the series. If a primary series is started with a bivalent Omicron containing mRNA vaccine and the same product is not readily available to complete the series, another bivalent Omicron-containing mRNA vaccine may be used to complete the series.3 References 1. Pfizer Canada ULC. Comirnaty Original and Omicron BA.4/BA.5 vaccine (COVID-19 mRNA vaccine, bivalent [Original and Omicron BA.4/BA.5]) product monograph. Kirkland, QC; July 6, 2023. (accessed July 18, 2023). 2. Health Canada. Drug and vaccine authorizations for COVID-19: list of applications received.(accessed July 18, 2023). 3. Health Canada. Interim guidance on the use of bivalent Omicron-containing COVID-19 vaccines for primary series. June 9, 2023. (accessed July 18, 2023).

Pfizer bivalent COVID-19 vaccine now approved for primary immunization

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