The two key groups in western countries are baby-boomers (likely acquired the infection from dentists/doctors reusing needles), and intravenous drug users. The best bang for your buck is in testing and treating this last population, but you have to be careful and try to do followups to prevent reinfection. It's worthwhile to test the baby boomer population as many of them could require liver transplants soon if not detected
My aunt is such a boomer. She got hvc in the military from a pneumatic vaccine injector. The DoD apparently discontinued this practice in the late 90s.
