TYPES OF HCV TESTING AND DIAGNOSTIC STRATEGIES


All testing technologies for HCV must be approved by the TGA and included in the ARTG24 before their use in Australia. Inclusion in the ARTG requires pre-market evaluation of the HCV diagnostic test commensurate with the purpose for which the test will be used.

HCV antibody tests

The primary tests used to determine exposure to HCV infection rely on serological detection of HCV antibodies (anti-HCV) and typically use a serum or plasma sample from venous blood. The terms HCV antibody and anti-HCV are equivalent, but in this policy HCV antibody is used throughout. Point-of-care tests are also available to determine the presence or absence of HCV antibody using whole blood from a capillary fingerstick sample. Samples yielding non-reactive results (HCV antibody negative) do not need to be further tested unless clinical considerations demand it, such as suspicion of a very recent infection due to specific risk behaviours.

The antibody seroconversion window period for HCV infection is prolonged and can vary from an average of 8 weeks up to 12 weeks.25,26 In the laboratory, confirmation of HCV antibody reactive (HCV antibody positive) samples is reliant on an alternative supplemental HCV antibody immunoassay. In place of a second confirmatory immunoassay, an HCV RNA test (also known as a nucleic acid amplification test [NAAT]), or an HCV core antigen test, not routinely available in Australia,27 can be used to ascertain whether the patient is currently infected with hepatitis C.

HCV RNA tests

A major goal of HCV testing is to detect current infection to facilitate linkage to care and treatment. Since HCV antibody assays only test for exposure to the virus, it is critical to ensure that people with a positive antibody test undergo additional testing to confirm current infection. Specifically, HCV RNA testing should be performed on all samples with positive HCV antibody results, where feasible. In the laboratory, this is typically conducted using a serum or plasma sample obtained from whole blood. Additionally, point-of-care tests are available to detect HCV RNA using whole blood from a capillary fingerstick sample.