On Sept. 28, 2023, Pfizer and BioNTech that Health Canada had authorized the companies’ Omicron XBB.1.5-adapted monovalent COVID-19 vaccine (COMIRNATYﾮ Omicron XBB.1.5) for ages 6 months and older.

For children 6 months through 4 years of age the updated vaccine was authorized for administration as a three-dose series in those without a history of completion of a COVID-19 primary vaccination course, or as a single dose for those with a history of completion of a COVID-19 primary vaccination course.