DR. FAUCI: Well, I don't think we should be that concerned right now about how long they're effective. I think they will be effective long enough that we will get to the point where we are not going to be necessarily worrying about a surge.
[...]
DR. FAUCI: Well, Yasmeen, there are several questions there. I think it's first important to point out that we don't really know when we may need a booster. I mean, we're making extrapolations saying that if the level of protection at the correlative immunity starts to wane and come down to below or at a critical level and you may start to see more breakthrough infections, at that point, that would be the trigger.
[...]
Of course, you have to put it into the context as follows. When you have an infectious disease and you want to, in essence, address it appropriately, there are three possibilities.

One, you could eradicate it. That's a very high bar because we've only eradicated one human infectious disease in our entire history, and that is smallpox, with a highly successful vaccination campaign [over 2,500 years].

The next thing is you can eliminate, and you generally do that by having certain countries, usually with good vaccination programs, essentially eliminate the presence of a particular pathogen in society.[
[...]
control. That's going to depend entirely on the success, which I believe we're going in the right direction, of the vaccine program, and the more and more people that get vaccinated--and that's the reason why we continue to push to get those people who are reluctant to get vaccinated--to, in fact, get vaccinated, because the closer we get to more and more people getting vaccinated < wipes tears > the more likely you'll LEAN TOWARDS elimination rather than just control.