Viral Load or Quantitative HCV tests measure the number of viral RNA particles in your blood. Viral load tests are often used before and during treatment to help determine response to treatment by comparing the amount of virus before and after treatment (usually after 3 months); successful treatment causes a decrease of 99% or more (2 logs) in viral load soon after starting treatment (as early as 4-12 weeks), and usually leads to viral load being not detected. Some newer viral load tests can detect very low amounts of viral RNA, and some laboratories no longer do qualitative HCV RNA tests if they
use one of these versions of viral load testing.