It is used to describe how effective a vaccine is against things like infection, and serious outcomes like hospitalizations and deaths.
When it comes to efficacy percentages, Sharma said that if a vaccine is 66% effective, that doesn't mean you'll have a 34% chance of getting COVID-19 after getting your doses.
She explained that all of the approved vaccines have different efficacy numbers but if you get any of them, your chance of getting infected is "greatly reduced."
She noted that "not one person" who was vaccinated in trials for the authorized vaccines died as a result of COVID-19.
Also, the vaccines have so far proved to be effective against "severe cases."
"Our advice to Canadians is to get whichever vaccine is available to you. It's that simple," Sharma said.
She mentioned as well that a vaccine can be the best in the world, but it will only work if someone agrees to get it.
It has been recommended by the National Advisory Committee on Immunization that provinces and territories give first doses to more people because evidence shows it gives sustained short-term protection.
Health Canada has a robust website with all the latest information on the vaccines and can answer any questions you may have. Click here for more information.