On Friday Oct. 29, NACI issued new guidance "strongly" recommending booster shots for seniors 80 and older. It also said boosters "may" be offered to other groups that "may be at increased risk of lower protection over time since vaccination, increased risk of severe illness or who are essential for maintaining health system capacity."

Those groups include:

Adults between the ages of 70 and 79.
Anyone who received two doses of the AstraZeneca/COVISHIELD vaccine or one dose of the Johnson & Johnson/Janssen (J&J) vaccine.
Adults in or from First Nations, Inuit and Métis communities.
Adults who are front-line health-care workers who have direct in-person contact with patients and who were vaccinated with a very short interval between their first and second doses (three or four weeks).
Booster shots should be given at least six months after the second dose of vaccine, NACI said. The boosters should also be one of the mRNA vaccines — Pfizer-BioNTech or Moderna, it said.

Although NACI makes recommendations, most aspects of health care, including vaccination, are under provincial or territorial jurisdiction. So it's ultimately up to the provinces and territories to decide who gets a booster shot and when.