SVR12

SVR12, or sustained virological response at 12 weeks, is a key endpoint in the treatment of hepatitis C virus (HCV) infection. It is defined as undetectable HCV RNA in a patient’s blood at least 12 weeks after completing antiviral therapy. HCV RNA is measured with a sensitive assay, with a typical lower limit of detection around 15 international units per milliliter.

SVR12 is used as a surrogate marker for virologic cure and is associated with favorable long-term outcomes, including reduced risk of cirrhosis progression, liver failure, hepatocellular carcinoma, and liver-related death. Historically, SVR24 was the standard endpoint, but SVR12 has become the preferred measure because it strongly correlates with SVR24 and allows earlier assessment of treatment success.

Measurement is performed via blood testing after the end of treatment. A result showing undetectable HCV RNA at the 12-week post-treatment visit indicates SVR12. If HCV RNA is detectable at or before the 12-week mark, the patient has not achieved SVR12, and further evaluation for relapse or possible reinfection may be considered. While relapse after SVR12 is rare, reinfection after achieving SVR12 is a separate clinical scenario and does not reflect failure of the initial treatment.

In modern regimens, particularly those based on direct-acting antivirals, SVR12 rates are high across most genotypes, though factors such as cirrhosis, prior treatment history, and adherence can influence the likelihood of achieving SVR12. SVR12 remains a central measure in clinical trials and routine practice for assessing hepatitis C therapy outcomes.