When post exposure is hepatitis c rna test conclusive? i have read ~99% 2-3 weeks. what about at 5 weeks?

Precise data not available, but probably also 99% at 5 weeks (i.e. conclusive for all practical purposes). Testing for hepatitis C virus (HCV) is not generally advised after any single exposure unless risk is especially high, such as unprotected anal sex in men having sex with other men, recent injection drug use, etc. HCV is not transmitted heterosexually, no testing needed.