100% protection might be important to you personally, but it does not matter on a societal scale. What does matter is to decrease as much as possible the mean n

100% protection might be important to you personally, but it does not matter on a societal scale. What does matter is to decrease as much as possible the mean number of new people infected per sick person. If that number is above 1, the growth is logistic (exponential in early stages), if it is lower but still above 1, it is exponential but with a longer doubling time ("flattening the curve"), and if it is below 1, cases will decrease.