https://www.gov.mb.ca/covid19/vaccine/eligibility-criteria.html#fourthdose
Second booster recommendations
Based on recommendations from the National Advisory Committee on Immunization, the following individuals are eligible to receive a second booster dose of COVID-19 vaccine:
residents of personal care homes and elderly persons housing congregate living sites (such as supportive housing and assisted living) with no age limit;
individuals aged 70 or older who live in the community; and
First Nations, Inuit and Metis people aged 50 or older, regardless of where they live.
The second booster should be Pfizer or Moderna and given at least six months after the last booster dose.