Elecsys® HCV Duo

Immunoassay for the qualitative dual detection of hepatitis C virus (HCV) core antigen and antibodies to HCV

Elecsys® HCV Duo
Immunoassay for the qualitative dual detection of HCV core antigen and antibodies to HCV

Hepatitis C is an inflammatory liver disease caused by infection with the hepatitis C virus (HCV), which can cause both acute and chronic hepatitis.1 HCV is a member of the Flaviviridae family and has a single-stranded, positive-sense RNA genome, which encodes 3 structural and 7 non-structural proteins.2,3 HCV is classified into 8 genotypes with a total of currently 90 subtypes.4

Hepatitis C represents a major global health burden: the total global prevalence of antibodies against HCV, indicating past exposure to HCV, was estimated to be 1.6 %, corresponding to approx. 115 million people with a past infection.5 The prevalence of HCV RNA positivity indicating active HCV infection or viremia was determined to be 0.75 %, corresponding to 58 million people. In 2019, 1.5 million new infections occurred and 290,000 people died of HCV.1,6

Most acute HCV infections (70 – 85 %) are asymptomatic and approximately 15 – 45 % of patients will clear acute infection. In case of symptomatic acute hepatitis C, symptoms usually appear within 7 – 8 weeks after exposure and consist of jaundice, malaise, and nausea (similar to hepatitis A and B).2,7-9 Chronic HCV infection is characterized by persistence of HCV RNA in the blood for longer than 6 months. Most chronic infections will lead to hepatitis and to some degree of fibrosis, which may be accompanied by relatively nonspecific symptoms such as fatigue. 20 % of people with chronic hepatitis C will eventually develop cirrhosis.2,7-9 Once cirrhosis is established, the risk of developing hepatocellular carcinoma (HCC) is 1 – 4 % per year.10 Highly efficacious direct-acting antiviral (DAA) combination therapies are now available which can cure more than 95 % of treated patients.11

Infection with HCV and the state of infection (acute or chronic) can be diagnosed by measuring HCV‑specific antibodies (anti‑HCV), and HCV RNA or viral antigens in patient serum or plasma samples. Measurement of the alanine aminotransferase (ALT) level is an associated indicator of liver inflammation or damage due to infection.2,7,12 International guidelines recommend initial screening by anti‑HCV testing. A positive anti-HCV result is recommended to be followed up by measuring HCV RNA or HCV antigen (HCV Ag) as markers of active infection.8,13-15

Anti-HCV antibodies are detected on average 6 – 12 weeks after infection, while HCV RNA and core antigen appear much earlier already in the incubation and acute phases of infection (2-14 days and 10-30 days after infection, respectively). Detection of HCV core antigen, as a surrogate marker of HCV RNA, is thus a means to shorten the diagnostic window period and confirm active infection.2,9,13,15-18

The Elecsys® HCV Duo assay comprises two test modules, one for the detection of HCV Ag (HCVAG) and one for the detection of anti-HCV (AHCV). HCVAG uses monoclonal antibodies for the detection of the HCV core antigen. AHCV uses synthetic peptides and a recombinant protein representing the core, NS3 and NS4 antigens for the detection of anti‑HCV antibodies. With the Elecsys® HCV Duo assay, HCV core antigen as well as antibodies to HCV can be detected simultaneously from a single specimen in two separate, but parallel reactions. The Elecsys® HCV Duo main test result is automatically calculated by the analyzer, while the individual HCV Ag and anti‑HCV results are also accessible.19

Elecsys HBsAg II

Elecsys® HCV Duo

  • Systems

    cobas e 402 / cobas e 801 analytical modules


  • Testing Time

    27 minutes

  • Calibration

    Individual 2-point calibration for HCV antigen and anti-HCV antibodies


  • cobas e flow

    Duplicate repeat testing of initially reactive samples (HCVDUOR)

  • Traceability

    HCVAG: Standardized against the WHO International Standard for Hepatitis C virus (HCV) core antigen, PEI code 129096/12
    AHCV: No internationally accepted standard for anti‑HCV exists

  • Interpretation

    HCVAG sub-result: COI <1.0 = non-reactive for HCV antigen / COI ≥1.0 = reactive for HCV antigen
    AHCV sub-result: COI <1.0 = non-reactive for anti-HCV / COI ≥1.0 = reactive for anti-HCV
    HCV Duo main result: calculated automatically based on the HCVAG and AHCV sub-results: HCVDUO COI <1.0 = non-reactive / HCVDUO COI ≥1.0 = reactive

  • Specimen types

    Serum collected using standard sampling tubes or tubes containing separating gel.
    Li-heparin, Na-heparin, K2-EDTA, K3-EDTA, ACD, CPD, CP2D, CPDA and Na-citrate plasma. Plasma tubes containing separating gel can be used.
    Specimen collected from living patients, blood donors, or individual organ, tissue or cell donors may be used, including donor samples obtained while the donor’s heart is still beating, and cadaveric blood specimens (specimens collected post-mortem, non-heart-beating).




  • Sample volume

    42 μL (HCVAG: 30 μL; AHCV: 12 μL)






  • Onboard stability

    31 days

  • Intermediate precision in positive samples

    HCVAG: CV* 3.0 – 4.8 % ; AHCV: CV 3.3 – 4.3 %

  • Analytical specificity

    99.41 % (95 % CI** 96.77 – 99.99 %); N = 180

  • Clinical specificity

    99.94 % (95 % CI 99.89 – 99.96 %); N = 23,165

  • Clinical sensitivity

    99.87 % (95 % CI 99.25 – 100 %); N = 743

* coefficient of variation; ** confidence interval


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  2. Hoofnagle, J.H. (2002). Course and Outcome of Hepatitis C. Hepatology 36, S21-S29.
  3. Lindenbach, B.D. and Rice, C.M. (2005). Unravelling hepatitis C virus replication from genome to function. Nature. 436, 933-938.
  4. International Committee on Taxonomy of Viruses (ICTV). Flaviviridae Study Group.Confirmed HCV genotypes/subtypes (May 2019). https://talk.ictvonline.org/ictv_wikis/flaviviridae/w/sg_flavi/56/hcv-classification.
  5. Gower E, et al. Global epidemiology and genotype distribution of the hepatitis C virus infection. Hepatology 2014;61:S45-S57.
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  9. Ahmad, J. (2017). Hepatitis C. BMJ 358, j2861.
  10. Lauer, G.M. and Walker, B.D. (2001). Hepatitis C virus infection. N Engl J Med. 345, 41-52.
  11. Pietschmann T. and Brown R.J.P. (2020). Hepatitis C Virus. Trends in Microbiology 27(4), 379-380.
  12. Dufour D.R. (2000). Diagnosis and Monitoring of Hepatic Injury. II. Recommendations for Use of Laboratory Tests in Screening, Diagnosis, and Monitoring. Clin Chem 46, 2050-2068.
  13. European Association for the Study of the Liver. (2020). EASL recommendations on treatment of hepatitis C: Final update of the series. J Hepatol. 73, 1170-1218.
  14. Centers for Disease Control and Prevention. Testing for HCV Infection: An Update of Guidance for Clinicians and Laboratorians. MMWR 2013;62(18):362-365.
  15. AASLD-IDSA. HCV Guidance: Recommendations for Testing, Managing, and Treating Hepatitis C. http://hcvguidelines.org. Last accessed: April 2022.
  16. U.S. Department of Health and Human Services, Centers for Disease Control and Prevention (2015). Viral Hepatitis Serology Training, Hepatitis C. Available at: https://www.cdc.gov/hepatitis/resources/professionals/training/serology/training.htm. Last accessed: October 2021.
  17. World Health Organization (2017). Guidelines on Hepatitis B and C Testing. https://www.ncbi.nlm.nih.gov/books/NBK442283/figure/annex6.fig1/.
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  19. Courouce, A.M. et al. (2000). Efficacy of HCV core antigen detection during the preseroconversion period. Transfusion 40, 1198–1202.
  20. Elecsys® HCV Duo (Mat. No. 08110697190) method sheet, V1 2021-06.