All testing technologies for HCV must be included on the Australian Register of Therapeutic Goods (ARTG) before their use in Australia. Inclusion on the ARTG requires pre-market assessment of the HCV diagnostic test commensurate with the purpose for which the test will be used.
HCV screening tests
Screening tests are serological assays used by laboratories performing diagnostic testing or screening of blood donations to determine the presence or absence of HCV antibody (anti-HCV), and typically use serum or plasma from venous blood. Those samples yielding non-reactive results (HCV antibody not detected) do not need to be further tested unless clinical considerations demand it, such as suspicion of a very recent infection. Note that the seroconversion window period for HCV infection can be lengthy, on average 8 weeks but can be up to 12 weeks.19,20,21 Reactive samples (HCV antibody detected) are subjected to a second alternative immunoassay to confirm true reactivity from false. The recombinant antigens used in the immunoassays are not an exact mimic of the virus proteins, so when screening a low prevalence population, some false reactivity can occur. Confirming reactivity in the alternative immunoassay minimises this risk.
HCV RNA tests
The presence of HCV antibody (anti-HCV detected) shows that the patient has HCV infection but does not indicate whether the infection is acute, chronic or resolved. This diagnosis is most commonly determined by testing for the presence of HCV RNA. Testing for HCV RNA is recommended for all patients shown to have an HCV antibody (anti-HCV) reactive sample. There is also an immunoassay available for HCV core antigen (HCVcAg), which can also identify acute or chronic infection although few laboratories in Australia offer this test.
Further tests may be used once HCV RNA has been detected. These tests include assays to quantify viral load and characterise the virus genotype.