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SARS-CoV-2 IgG Assay

Updated: Feb 1, 2021

Rapid and accurate antibody testing on a large scale is key to address the challenges of the COVID-19 pandemic. Over time, SARS-CoV-2 IgG antibodies remain the primary antibodies present.



The Siemens Healthineers SARS-CoV-2 IgG (COV2G) Assay is the first FDA EUA-authorized semi-quantitative assay to help clinicians assess the level of an individual‘s immune response over time.

“Being able to measure a patient’s relative level of antibodies in response to a previous SARS-CoV-2 infection may be useful as we continue to learn more about the virus and what the existence of antibodies may mean. There are still many unknowns about what the presence of SARS-CoV-2 antibodies may tell us about potential immunity, but today’s authorizations give us additional tools to evaluate those antibodies as we continue to research and study this virus.” Tim Stenzel, M.D., Ph.D., Director of the Office of In Vitro Diagnostics and Radiological Health in the FDA’s Center for Devices and Radiological Health


Results can be produced in as little as 16 minutes on the Dimension® and Dimension Vista® Systems† and 25 minutes on the Atellica® IM Analyzer with a capacity to process up to 440 assays per hour§ along with the sensitivity and specificity laboratories have come to expect from us.


Siemens Healthineers offers a robust portfolio of reliable antibody tests to support patient care

We offer both the SARS-CoV-2 IgG antibody assay and the SARS-CoV-2 Total antibody assay. The combination of these assays provides a complete picture of a patient’s serological status for the most accurate results throughout his or her continuum of care.


SARS-CoV-2 IgG (COV2G) Qualitative and Semi-quantitative Assay The COV2G assay is a qualitative and semi-quantitative SARS-CoV-2 antibody assay that enables clinicians to detect the level of IgG antibodies in a patient’s blood sample and assess relative changes over time. The assay is more appropriate for later seroconversion. With this numerical value, clinicians will have a baseline and be better equipped to track the long-term duration of an individual’s immune response. Comparison of numerical results will help determine how the immune response develops in an individual and persists over time.

SARS-CoV-2 Total (COV2T) Assay The COV2T assay detects both IgM and longer-lasting IgG antibodies with 100% sensitivity‡ and 99.8% specificity for recent and prior infection. Total antibody assays can be used as an adjunct to PCR tests to identify a patient’s immune response during early infection and aid in clinical assessment

Smart selection of the S1 RBD antigen to detect antibodies that block virus entry into cells

We smartly selected the receptor-binding domain (RBD) of the S1 spike antigen to detect antibodies that block the virus entry into the cells. This selection is aligned with the multiple vaccines in development that target or include the SARS-CoV-2 S1 RBD used in our assay, with the goal of producing protective antibody.

The COV2G assay detects antibodies to the S1 RBD antigen. S1 RBD antibodies are relevant to vaccines incorporating this immunodominant region to elicit neutralizing (and therefore likely protective) antibodies in vaccinated subjects.3 The spike protein and particularly the RBD are the most common target of vaccine designs.


Accurate identification of immune response to support long term COVID-19 management



The COV2G assay provides a qualitative (negative/positive) and semi-quantitative (index value) result that enables clinicians to detect the level of IgG antibodies in a patient’s blood sample and assess relative changes over time. The addition of a semi-quantitative IgG result is an important step in the global pursuit to establish an individual’s immunity. With this numerical value, clinicians will have a baseline and be better equipped to assess changes of an individual’s immune response to the SARS-CoV-2 virus.

Why Specificity Matters High specificity is crucial for an accurate antibody assay. The Centers for Disease Control and Prevention guidelines for COVID-19 antibody testing states, “choosing a test with a very high specificity, perhaps 99.5% or greater, will yield a high positive predictive value in populations tested with prevalence >5%.”2 There are numerous tests that claim to detect antibodies to the virus, but only a small percentage have been shown to be highly accurate.

SARS-CoV-2 IgG Assay Specificity

  • Atellica IM: 99.95%

  • ADVIA Centaur XP/XPT: 99.89% 

  • Dimension EXL: 100%

  • Dimension Vista: 100%