Elecsys® HBsAg II Auto Confirm

Immunoassay for the confirmation of presence of the hepatitis B surface antigen (HBsAg)

Elecsys Reagent Pack

Immunoassay for the confirmation of presence of the hepatitis B surface antigen (HBsAg)

Hepatitis B is a potentially life-threatening liver infection caused by the hepatitis B virus (HBV).1 Hepatitis B surface antigen (HBsAg) is a polypeptide component of the external envelope of HBV.2 After infection, HBsAg is the first immunologic marker detectable in serum.3 HBsAg assays are used within the scope of diagnostic procedures for persons with suspected acute or chronic HBV infection and prevent the transmission of the virus by blood and blood products.1,4

Despite the high true positive rate of repeatedly reactive HBsAg results, the seriousness of the diagnosis, with its potential medical, social, and economic implications mandates that a confirmatory test is attempted on all repeatable positive specimens.5

The Elecsys® HBsAg II Auto Confirm assay is a fully automated confirmatory assay, based on the principle of specific antibody neutralization.6


Automation of analytical steps and result determination via cobas e flow


All steps needed to perform the confirmatory testing with the Elecsys® HBsAg II Auto Confirm assay are automated, including the final calculation.6

Automation of analytical steps and result determination via cobas e flow
Elecsys HBsAg II

Elecsys® HBsAg II Auto Confirm

  • Systems

    cobas e 402, cobas e 801 analytical units

  • Test principle

    Parallel measurements for antibody-mediated neutralization of HBsAg (confirmatory assay)

  • Calibration


  • Interpretation

    COI of control reaction and confirmation result and interpretation

    COI ≥ 0.81 ≤ 60 % Confirmed reactive
    COI ≥ 0.81 > 60 % Confirmed non-reactive
    COI < 0.81 ≤ 60 % Indeterminate
    COI < 0.81 > 60 % Confirmation not valid

  • Sample material

    Samples repeatedly reactive on Elecsys® HBsAg II. Sample types claimed for Elecsys® HBsAg II can be used.

  • cobas e flow

    The HBsAg II Auto Confirm cobas e flow automatically calculates the confirmation result of the sample. Three cobas e flows are available, depending on Elecsys® HBsAg II titer (COI < 100, COI ≥ 100 or independent of HBsAg titer).

    HBSAG2CL (low)
    Low titer HBsAg, HBsAg 0.9 ≤ COI < 100
    HBSAG2CH (high)
    High titer HBsAg, COI ≥ 100
    HBSAG2C (all titer)*
    Independent of titer, COI ≥ 0.9

  • Testing time

    27 min HBSAG2CL (low)
    27 min HBSAG2CH (high)
    27 - 54 min HBSAG2C (all titer)*

  • Sample volume

    108 μL HBSAG2CL (low)
    24 - 36 μL HBSAG2CH (high)
    24 – 132 μL HBSAG2C (all titer)*

  • Requires Diluent Universal

    No HBSAG2CL (low)
    Yes HBSAG2CH (high)
    Yes HBSAG2C (all)*

  • Onboard stability

    16 weeks






  • Precision in positive samples

    In a precision study over 21 days weakly positive, moderate positive and high positive samples were reliably found “Confirmed reactive” (n = 84 determinations per sample)

  • Relative sensitivity

    The presence of HBsAg was confirmed in 309 samples with different titers of HBsAg from individuals with acute or chronic hepatitis B infection, resulting in a 100 % sensitivity. The 95 % lower confidence limit was 99.04 %.

  • Relative specificity

    7 native false positive samples and 7 artificial interfering false positive samples were tested with the Elecsys® HBsAg II Auto Confirm and correctly not neutralized

* Use of “HBSAG2C” may reduce average device throughput and increase average reagent consumption compared to the use of the titer dependent “HBSAG2CL” and “HBSAG2CH”.



  1. WHO. Hepatitis B Fact sheet. Available at: https://www.who.int/en/news-room/fact-sheets/detail/hepatitis-b, accessed February 2021.
  2. Norder, H., Couroucé, A.M., Coursaget, P. et al. (2004). Genetic diversity of hepatitis B virus strains derived worldwide: genotypes, subgenotypes and HBsAg subtypes. Intervirology 47, 289-309.
  3. Liaw,Y.F., Chu, C.M. (2009). Hepatitis B infection. Lancet 373, 582-592.
  4. Yuen, M.F., Chen, D.S., Dusheiko, G.M., et al. (2018) Hepatitis B virus infection. Nature Reviews Disease Primers 18035. doi:10.1038/nrdp.2018.35.
  5. Hollinger, F.B, Dienstag, J.L. (2005) Hepatitis B and D Viruses. In: Manual of Clinical Microbiology. 7th Edition. Edited by Murray, P.R., Baron, E.J, Pfaller, M.A., Tenover, F.C., Yolken, R,H. American Society for Microbiology. USA.
  6. Elecsys® HBsAg II Auto Confirm. Package Insert Material Number 08741034190.