I haven't been updated on this in a while, but the prevailing idea early on seemed to be that the reduction is achieved through shortening the infectious time,

I haven't been updated on this in a while, but the prevailing idea early on seemed to be that the reduction is achieved through shortening the infectious time, not so much by doing anything about the level of transmission before it's suppressed. Essentially the current vaccines wouldn't give any mucosal protection worth mentioning in itself, but since there are (hopefully) relevant lymphocytes in circulation, the host has more in the way of specific countermeasures ready to infiltrate from the bloodstream and shut down the worst of the shedding, sooner than if the specific immunity had to be developed first. So we'd have more or less unfettered susceptibility for getting infected (superficially) and pretty much just as high levels of infectious excretions, but for maybe half as long a time at the highest levels. Would you happen to know if that picture still holds?