From the Guidelines
A positive Hepatitis C (HCV) antibody test result indicates that the person has been exposed to the hepatitis C virus at some point in their life, but it does not necessarily confirm a current active infection. To determine if there is an active hepatitis C infection, a follow-up HCV RNA test is required, as recommended by the American Journal of Obstetrics and Gynecology 1. This test detects the presence of the virus itself in the blood.
Key Points to Consider
- A positive anti-HCV antibody test result can indicate the patient is currently positive, was positive, or is negative, as the antibody persists throughout life 1.
- The standard screening test for HCV is an anti-HCV antibody test, and a positive test result should be followed by a quantitative nucleic acid test for HCV RNA 1.
- If the HCV RNA test is positive, it confirms an active hepatitis C infection, and treatment with direct-acting antiviral medications is typically recommended 1.
- If the HCV RNA test is negative, it means the person either cleared the virus naturally or was successfully treated in the past, and no further action is needed, but the antibody will remain positive for life 1.
Clinical Implications
- The hepatitis C antibody remains in the blood even after the virus is cleared, which is why the initial antibody test alone cannot distinguish between past and current infections 1.
- The persistence of antibodies is the body's way of maintaining long-term immunity against the virus 1.
- For persons who might have been exposed to HCV within the past 6 months, testing for HCV RNA or follow-up testing for HCV antibody is recommended, as suggested by the Morbidity and Mortality Weekly Report 1.
Testing Sequence
- The testing sequence for identifying current hepatitis C virus (HCV) infection begins with either a rapid or a laboratory-conducted assay for HCV antibody in blood, followed by NAT for HCV RNA if the result is reactive 1.
From the Research
Hepatitis C Antibody Test Result Interpretation
A positive Hepatitis C (HCV) antibody test result indicates that an individual has been exposed to the HCV virus at some point in their lives 2, 3, 4. This does not necessarily mean that the individual is currently infected with the virus, as the test detects the presence of antibodies to HCV, which can remain in the blood even after the infection has been cleared.
False-Positive Results
False-positive results can occur, especially in low-risk populations, and further diagnostic testing is necessary to confirm the diagnosis 2, 3, 4. The use of a signal-to-cutoff (S/CO) ratio can help to identify false-positive results, with very low levels of Anti-HCV indicating false-positive results and low antibody levels frequently related to false-positive results 2.
Confirmatory Testing
Confirmatory testing, such as recombinant immunoblot assay (RIBA) and HCV RNA testing, is necessary to confirm the diagnosis of HCV infection 3, 4, 5. The choice of confirmatory test depends on the clinical setting and the likelihood of a true-positive result.
Key Points
- A positive HCV antibody test result indicates exposure to the HCV virus, but not necessarily current infection 2, 3, 4.
- False-positive results can occur, especially in low-risk populations, and further diagnostic testing is necessary to confirm the diagnosis 2, 3, 4.
- Confirmatory testing, such as RIBA and HCV RNA testing, is necessary to confirm the diagnosis of HCV infection 3, 4, 5.
- The use of a S/CO ratio can help to identify false-positive results and guide further diagnostic testing 2.
- HCV RNA testing is necessary to confirm current infection and guide treatment decisions 3, 4, 5, 6.