Health Canada has authorized an updated version of Moderna's COVID-19 booster vaccine.

The new bivalent shot targets the Omicron BA.4/BA.5 subvariants and is meant to be used as a booster dose for those aged 18 years and older.

It comes two months after Health Canada authorized a bivalent booster from Moderna that targeted the Omicron BA.1 subvariant and the original strain.

Health Canada says a bivalent booster triggers "a strong immune response" against both of the more recent Omicron subvariants, as well as the original SARS-CoV-2 virus strains.

The National Advisory Committee on Immunization (NACI) says Omicron BA.4 and BA.5 are the dominant strains in circulation.

They feature several key mutations from the original SARS-CoV-2 virus, leading NACI to strongly recommend bivalent boosters that target Omicron.