The number of people you need vaccinated is N where N * (vaccine efficiency) = (herd immunity threshold = ~ 70%), so in the case of the higher efficiency vaccin

The number of people you need vaccinated is N where N * (vaccine efficiency) = (herd immunity threshold = ~ 70%), so in the case of the higher efficiency vaccines N should be between 75% and 85% Though anything above (efficiency * vaccinated) above 50% should make a significant dent on the pandemic