The biotechnology company Moderna, Inc., which was a pioneer in the development of messenger RNA (mRNA) therapeutics and vaccines, has announced that Health Canada has authorised the use of its BA.4/BA.5 Omicron-targeting bivalent COVID-19 booster vaccine, mRNA-1273.222, as a booster dose for active immunisation against COVID-19 caused by the SARS-CoV-2 virus in individuals who are 18 years of age or older. The booster dose of mRNA-1273.222 is 50 micrograms, and it contains 25 micrograms of mRNA that codes for the spike protein of BA.4/BA.5, as well as 25 micrograms that code for the original strain of the SARS-CoV-2 virus.
The licencing of mRNA-1273.222 by Health Canada was based not only on pre-clinical data for mRNA-1273.222, but also on clinical data from a Phase 2/3 trial that investigated mRNA-1273.214. A Phase 2/3 clinical trial for the mRNA-1273.222 is now underway with complete enrollment, and initial data are anticipated to be available by the end of this year.
After the approval of mRNA-1273.214 (SPIKEVAXBivalent) in September, mRNA-1273.222 is the second bivalent COVID-19 vaccine developed by Moderna that has been given the green light by Health Canada. According to the findings of a clinical investigation, administering a booster dosage of mRNA-1273.214 resulted in an increase in neutralising geometric mean titers against Omicron BA.1 that was about eight times greater than the levels observed at baseline. Additional findings demonstrated that the elevated antibody titers were maintained ninety days following the administration of the drug.
In addition, mRNA-1273.214 induced considerably greater levels of neutralising antibody responses against Omicron BA.4/BA.5 28 days following injection in comparison to mRNA-1273. 28 days following injection, potent responses were also found against Omicron BA.2.75, demonstrating that the bivalent booster triggers broad cross-neutralization against Omicron variants.