by the end of Republic Taris this is a first-world measles epidemic, not a third-world AIDS epidemic.
The Rakghoul plague is extremely virulent and people who are infected can turn within hours
. Even if we assume 100% success rate in the vaccine (which is impossible) there are thousands of people on Taris (including pirates and scavengers who don't exactly have Republic support) and what's worse, because of how virulent the Rakghoul plague is, two rakghouls from the same social group can have sufficiently different strains that the vaccine will only work against one of them - if that!
It's certainly not a third-world AIDS epidemic, it's a third-world bubonic plague
epidemic. AIDS has the decency of being easy to contain in theory and only spreading through ignorance and carelessness, whereas the Rakghoul plague spreads aggressively
through its hosts actively attacking anything in sight.
The Rakghouls can even breed amongst themselves in the modern era (which is how they've thrived despite having no victims to infect for centuries) so exterminating them conventionally is as feeble a gesture as exterminating rat or rabbit populations... except if you screw up here
, you'll become
part of the problem.