Canadian Snowbirds heading home-Antigen Rapid Tests required

....one of the points she makes is does it make sense to give previously infected populations a vaccine dose, when billions of population have not yet been infected (we are talking passed tense here, of course) had a single dose (ie. more efficient dose distribution)? How many in the world still have not as yet received a single vaccine dose to this day, and have not yet been infected (likely a small uninfected cohort; but the point still....) in 2022?