Canadians at risk of severe illness due to COVID-19 are being advised to get an additional booster dose this spring.

The National Advisory Committee on Immunization, or NACI, says that includes adults 80 and up, those living in long-term care homes and other congregate settings for seniors or those with complex medical needs.

It's also calling on adults 18 and older who are moderately to severely immunocompromised, either due to medical treatment or an underlying health condition, to get a booster shot.

NACI says adults between 65 and 79 should also get vaccinated, especially if they do not have a known history of being infected with the virus that causes COVID-19.

The committee says the Omicron-containing bivalent mRNA-based vaccines are the preferred option for booster shots and the recommended interval is six or more months from the last COVID-19 dose or infection with the virus, whichever is longer.

NACI says it will continue to monitor emerging evidence on the virus, including how long protection from bivalent boosters lasts, to provide further recommendations on the timing of subsequent boosters, if they are warranted.

This report by The Canadian Press was first published March 3, 2023.