> I don't see how eradication programs would work with such a differential
Its all about R0. If the efficacy (and compliance) is above the 1 / R0 rate, then eradication is possible.
As its "efficacy times compliance", the number we wish to maximize is the smaller number. Efficacy may have dropped to 60% (double shot vs Delta), but a 3rd booster brings the efficacy back up to 90%.
Compliance however, is stuck around 60% in the USA in general, and a large number of people are refusing to get the booster. As such, compliance is the number we need to work on right now.
--------
Going from 90% to 99% vaccine efficacy barely does anything, because our vaccine compliance numbers are so damn low.