What Is a Sustained Virologic Response?

Understanding the Definition and Meaning of a Hepatitis C "Cure"

Man taking a pill for hepatitis C
What is the meaning of a sustained virologic response with treatment for hepatitis C?. Photo Credit: Paul Bradbury/Getty Images

Definition: Sustained Virologic Response

A sustained virologic response (SVR) for people with hepatitis C infection simply means that there is no evidence of hepatitis C virus (HVC) in your blood after you have received hepatitis C treatment?

What Does Sustained Virologic Response (SVR) Mean?

SVR is the ultimate goal of HCV therapy and, in most cases, can be clinically defined as a "cure" if your HCV viral load remains undetectable 24 weeks after completion of treatment.

In almost all but a few cases, people with an SVR of 24 weeks are unlikely to experience viral rebound (i.e., a return of virus). Most research suggests that rebound rates are as a low as 1 to 2 percent in such cases.

Defining SVR and Other Virologic Responses

Following initiation of hepatitis C therapy, your blood is tested to measure viral activity, with the ultimate goal of achieving an undetectable viral load. An undetectable result doesn't necessary mean zero or the complete absence of viral activity in the body; rather it is defined as having no detectable virus in your blood using current testing technologies.

Each stage of response is given a classification, with some stages correlating to greater or lesser likelihood of treatment success.

TermMeaningDefinitionPrognosis
RVRRapid viral responseAn undetectable viral load after four weeks of treatmentGenerally more likely to achieve SVR
eRVRExtended rapid viral responseAn undetectable viral load at week 12, following the initial RVRGenerally more likely to achieve SVR
EVREarly viral responseAn undetectable viral load or a 99% reduction in viral load by week 12More important as a predictor of treatment outcome as failure to achieve EVR correlates to less than 4% chance of achieving SVR
ETREnd of treatment responseAn undetectable viral load achieved by the end of week 12Not helpful in predicting treatment outcomes
Partial responder Able to achieve EVR but unable to sustain an undetectable viral load 24 weeks after therapy completionConsidered treatment failure
Null responder Unable to achieve EVR by week 12Treatment is typically terminated if EVR is not achieved by week 12
SVRSustained viral responseAble to sustain undetectable viral load for 12 weeks (SVR-12) and 24 weeks (SVR-24) following completion of therapySVR-24 is considered a “cure,” while patients with SVR-12 are usually able to achieve SVR-24

What Can Increase Your Chance of SVR?

One of the main determinants of SVR success is timing, with earlier therapy benefiting patients more than delayed therapy. By treating your infection before there is marked liver damage (or, ideally, any damage), you generally have a better chance of achieving a clinical cure for HCV.

Additionally, newer class direct acting antivirals (DAAs) have had a profound effect on cure rates in people with chronic HCV infection. Even in people with compensated cirrhosis, who previously had a 50/50 chance of treatment success, SVR rates are gradually climbed to 95 percent and above in many cases.

Phase III human trials have estimated the following cure rates for newly treated (naïve) and previously treated (experienced) patients with HCV:

  • Zepatier (grazoprevir + elbasvir) used with or without ribavirin: 95 percent naïve and experienced

Failing to Achieve SVR Does Not Mean Treatment Has Failed

While the goal of HCV therapy is to effectively eradicate the virus and to live a healthy, hepatitis-free life, you shouldn't despair if you are unable to achieve these goals. Even if you only have partial response, studies have shown that the benefits to the liver can be profound, not only slowing the course of the disease but in some cases reversing fibrosis even in those with marked liver damage.

If you fail your first- or second-line of therapy, take time to monitor your blood results with your doctor.  If you feel you are ready to try again, your doctor can perform a number of tests to determine which drugs may provide you the best chance of achieving SVR success.

Coping with Hepatitis C

Coping with a heptatitis C infection, as with other chronic condition, takes a village. In addition to allowing your family to help you in your journey, many people find comfort in being part of the active hepatitis C community online or a chronic hepatitis support group. And just as we are learning about the importance of nutrition for people with cancer, and how a good diet can be just as important as chemotherapy, becoming knowledgable about chronic hepatitis nutrition can have value not only in how you feel, but in how you respond to treatment. The following information on hepatits C can help direct you to other answers you may be seeking as you cope with this disease.

Sources:

Chopra, S., and D. Muir. Treatment Regimens for Chronic Hepatitis C Virus Genotype 1. UpToDate. Updated 09/14/16.

Kattakuzhy, S., Wilson, E., Sidharthan, S. et al. Moderate Sustained Virologic Response Rates With 6-Week Combination Directly Acting Anti-Hepatitis C Virus Therapy in Patients With Advanced Liver Disease. Clinical Infectious Disease. 2016. 62(4):440-7.

Kattakuzhy, S., Wilson, E., Sidarthan, S. et al. Evolution of Resistance Associated Variants During Initial Treatment, Viral Failure, and Re-Treatment with Directly Acting Antiviral Therapy (NIH SYNERGY Trial). AASLD Liver Meeting; 2015; abstract 220.

Smith-Palmer, J., Cerri, K., and W. Valentine. Achieving Sustained Virologic Response in Hepatitis C: A Systematic Review of the Clinical, Economic and Quality of Life Benefits. BMC Infectious Disease. 2015. 15:19.

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