The National Advisory Committee on Immunization has expanded eligibility guidelines for booster shots of COVID-19 vaccines. The committee now recommends mRNA boosters to people who received two doses of the Oxford-AstraZeneca vaccine, one dose of a Janssen vaccine, adults over the age of 70, front-line health-care workers with a short interval between their first two doses, and people from First Nations, Inuit and Métis communities.