People at high risk of severe disease from COVID-19 infection should be offered a booster shot this fall, regardless of how many boosters they've previously received, the National Advisory Committee on Immunization (NACI) said on Wednesday.
That group includes everyone age 65 and older, NACI's updated guidance said.
Everyone else — age 12 to 64 — "may be offered" the additional doses in the fall, NACI said.
NACI said it will provide recommendations on the type of booster to be given when evidence about multivalent vaccines — which prime the body's defences against multiple variants, including Omicron and its subvariants — becomes available.
"Manufacturers are working on new COVID-19 vaccines, including multivalent vaccines and vaccines specifically targeting VOCs [variants of concern], although their exact characteristics and timing of availability in Canada are not yet known," NACI said.
World Health Organization Director General Tedros Adhanom Ghebreyesus said in a statement on Wednesday that Omicron subvariants BA.4 and BA.5 have caused COVID-19 case numbers to rise in 110 countries, "causing overall global cases to increase by 20 per cent."
Dr. Theresa Tam, Canada's chief public health officer, has also said those Omicron subvariants appear to be on the rise in this country.
On Tuesday, advisers to the U.S. Food and Drug Administration recommended that the next wave in COVID-19 booster shots should include a component that targets Omicron to combat the more recently circulating subvariants.
NACI recommended that booster shots happen in the fall because, as with other respiratory viruses, "incidence of COVID-19 may increase in the later fall and winter seasons," and new variants of concern could emerge.
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In addition to those 65 years and older, NACI strongly recommends a fall booster for:
Long-term care residents.
People with underlying medical conditions, including cardiac disease, diabetes, cancer and kidney disease.
People who are immunocompromised.
People who are pregnant.
Adults who are disproportionately affected by COVID-19 (including racialized communities).
Adults who are marginalized (including people with disabilities).
Adults from First Nations, Inuit and Métis communities.
Residents of congregate living settings, including group homes, shelters, correctional facilities and quarters for migrant workers.
Health officials emphasize that three doses of the current approved vaccines continue to provide good protection against severe COVID-19 illness, hospitalization and death.