OTTAWA - Canadians should get another COVID-19 vaccine booster in the fall if it's been at least six months since their last dose or COVID-19 infection, the National Advisory Committee on Immunization (NACI) said on Tuesday.

“Booster doses in the fall will be formulations updated to target more recent, immune-evasive SARS-CoV-2 variants,” the NACI statement said.

“Individuals vaccinated with the updated formulation are expected to benefit from a better immune response against these variants compared to current vaccines,” it said.

Both Pfizer-BioNTech and Moderna have started the process to get the new formulations of their mRNA COVID-19 vaccines approved by Health Canada, the department said in an email to The Canadian Press.

“This regulatory review has not yet been completed,” Health Canada said. “More information on this vaccine, including the authorized age groups, will be available in the coming months.”

NACI continued to strongly recommend that anyone five years of age and older who hasn't yet been vaccinated should be immunized with a primary two-dose series of an mRNA vaccine.

It also issued a “discretionary recommendation” that children six months to five years of age who haven't yet been vaccinated get the two-dose primary series of an mRNA vaccine.

The existing bivalent Omicron-containing mRNA vaccines can be used for people receiving their first two-dose vaccination series, NACI said.

Immunization this fall is “particularly important for those at increased risk of COVID-19 infection or severe disease,” NACI's statement said.

Those vulnerable groups include people aged 65 and older, residents of long-term care homes or other group living settings, people with underlying medical conditions, people who are pregnant, people from First Nations, Metis and Inuit communities, people who are racialized and people who provide essential community services, it said.

The mRNA vaccines available in Canada are manufactured by Pfizer-BioNTech and Moderna.

Although mRNA COVID-19 vaccines are “preferred,” NACI said Novavax's Nuvaxovid should be offered as a booster to adults 18 years of age and older who are “unwilling or unable to receive an mRNA vaccine.”

This report by The Canadian Press was first published July 11, 2023.