I outlined to a coworker recently how this works as a rolling control mechanism. The boosters will never stop and they act as a periodic compliancy check. You get to participate in society as long as you keep doing as you're told, but as soon as you start to hesitate and skip an injection you get hit with a bunch of stuff to make life hell because how dare you not be completely obedient. It's designed to punish the peasantry before it even starts to contemplate rebellion against the aristocracy.