The sound byte is false, but the effects of the sound byte were worth the lie, and the people who were in the medical field knew this.
The assumption that "a vaccine gives 100% immunity or it is useless" is a false premise. The PR person may have given a false sound byte because saying words with enough context was being attacked by political zombies.
A vaccine based on mRNA (blueprints of part of a virus) were never intended for 100% immunity. It was mainly to make it so you weren't hospitalized while the hospitals were full of normal hospitalizations (strokes, concussions, etc.), And guaranteed death to yourself or the person you displaced (that is why they said flatten the curve of intense vaccine free infections). Promotion of mass vaccination (even with the small risks associated with vaccination) was 100% the best choice for everyone that could. You could still infect people while infected with the real/live coronavirus.
I think that flu vaccines used to be a shot in the dark with 20% chance to be the dominant flu strain that grew/spread in an individual year. The only reason you didn't hear about it was that flu infection doesnt result in hospitalization.