On June 6^th, the Ontario government updated its guidance and gave the go-ahead on mixing mRNA vaccines for second shots, meaning an initial Pfizer vaccine could then be followed by a Moderna one, or vice versa. The COVaxON Vaccination Management System now allows for the mixing of brands to increase efforts to vaccinate Ontarians. However, mixing vaccines should only occur in events where the same mRNA vaccine is not available at the time of second dose administration. This update comes a week after the National Advisory Committee on Immunization (NACI) advised that Canadians who received AstraZeneca vaccine as their first dose could receive an mRNA vaccine (Pfizer/Moderna) as their second dose.