Use for the qualitative detection of IgG antibodies to evaluate exposure to SARS-CoV-2.

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Antibody Tests

• COVID-19 IgG, Qualitative by CIA
• COVID-19 IgG, Semi-Quantitative by CIA

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Both COVID-19 serology assays offered by ARUP have received FDA Emergency Use Authorization (EUA). Please visit the FDA website, EUA Authorized Serology Test Performance, for more information. Additionally, ARUP verified that both assays perform according to the manufacturer’s claims.

There are currently no recommendations for using antibody tests, including these tests, to assess response to vaccination. Additionally, these assays do not indicate immunity to COVID-19 or protection from reinfection with COVID-19.

Antibody Test Result Interpretation

Detection of IgG antibodies indicates exposure to SARS-CoV-2. Importantly, it has not yet been established that the presence of SARS-CoV-2 IgG antibodies implies immunity. Furthermore, individuals may still be infectious for some time after seroconversion occurs and antibodies become detectable. For this reason, a positive antibody result should not alter quarantine, isolation, social distancing, or PPE practices.

IgG results should not be used for diagnosis. Molecular tests are the only tests currently recommended for the diagnosis of COVID-19 infection.

SARS-CoV-2 IgG antibodies are likely to be present in a majority of individuals approximately two weeks after the onset of COVID-19 symptoms. If a specimen is collected too early, antibody tests can yield false-negative results. False-positive results can occur and may be due to past or present infection with non-SARS-CoV-2 coronavirus strains, such as coronavirus HKU1, NL63, OC43, or 229E. False-positive results are also possible in low-prevalence settings, even when an antibody test has >98.0% specificity.

Before you order: To provide public health departments with vital information on the spread of COVID-19, please submit the Patient Demographics Form for Public Health Reporting ONLY if complete demographic information is not transmitted to ARUP.

 

COVID-19 IgG, Qualitative by CIA (Target: Nucleocapsid Protein)

Test: COVID-19 IgG, Qualitative by CIA (3002776)

Methodology

This chemiluminescent immunoassay (CIA) performed on the Abbott ARCHITECT platform detects IgG antibodies specific to the nucleocapsid protein of SARS-CoV-2.

Results Reporting

Results are reported as “negative” or “positive.”

Sensitivity and Specificity

Performance of COVID-19 IgG, Qualitative by CIA

Antibody	Performance Measure	Estimate of Performance	95% CI
IgG	Sensitivity	100% (88/88)	95.8% to 100%
IgG	Specificity	99.6% (1,066/1,070)	99.0% to 99.9%
IgG	PPV at prevalence = 5%	93.4%	84.0% to 97.3%
IgG	NPV at prevalence = 5%	100%	99.8% to 100%
CI, confidence interval; NPV, negative predictive value; PPV, positive predictive value Data source: https://www.fda.gov/medical-devices/emergency-situations-medical-devices/eua-authorized-serology-test-performance

Pricing

The price of the COVID-19 IgG, Qualitative by CIA test (3002776) is $40 to our hospital and laboratory clients. ARUP does not charge patients directly for laboratory services.

Fact Sheets

COVID-19 IgG, Semi-Quantitative by CIA (Target: Spike Protein)

Test: COVID-19 IgG, Semi-Quantitative by CIA (3003648)

Methodology

COVID-19 IgG, Semi-Quantitative by CIA is a chemiluminescent immunoassay (CIA) performed on the ADVIA Centaur XPT platform. The assay detects IgG antibodies specific to the spike protein (S1) of SARS-CoV-2 (COVID-19). This test is authorized for the detection of antibodies to SARS-CoV-2 in human serum and plasma.

Results Reporting

Results are reported as “negative” or “positive,” along with an index value.

Index Value	Result	Interpretation
<1.00	Negative	Human antibodies to SARS-CoV-2 were not detected in the sample above the limit of detection
≥1.00	Positive	Human antibodies to SARS-CoV-2 were detected, suggesting possible exposure to COVID-19

A negative result does not rule out infection because patients may not have detectable antibodies early in the course of infection or may not develop detectable antibodies. Diagnostic testing for SARS-CoV-2 is recommended if current infection is suspected.

Sensitivity and Specificity

Performance of COVID-19 IgG, Semi-Quantitative by CIA

Antibody	Performance Measure	Estimate of Performance	95% CI
IgG	Sensitivity (PPA)	100% (42/42)	91.6% to 100%
IgG	Specificity (NPA)	99.9% (1,829/1,831)	99.6% to 99.9%
IgG	PPV at prevalence = 5%	98.0%	92.4% to 99.4%
IgG	NPV at prevalence = 5%	100%	99.6% to 100%
CI, confidence interval; NPA, negative percent agreement; NPV, negative predictive value; PPA, positive percent agreement; PPV, positive predictive value Source: https://www.fda.gov/medical-devices/emergency-situations-medical-devices/eua-authorized-serology-test-performance

Fact Sheets

Vaccine-Induced Immune Thrombotic Thrombocytopenia

Patients with vaccine-induced immune thrombotic thrombocytopenia (VITT) have been described as having platelet-activating antibodies detectable with PF4-heparin ELISA assays, and possibly with functional assays such as the serotonin release assay. Only a limited number of patients have been described to date, and testing algorithms remain in development. For more information, please refer to the Vaccine-Induced Immune Thrombotic Thrombocytopenia Testing section in the ARUP Consult COVID-19 topic.

Cytokine Support Testing

This testing is used primarily for research and to support attempts to understand the pathogenesis of immune, infectious, allergic, or inflammatory disorders. Currently, there are not well-defined guidelines on how the results should be interpreted and/or used to guide treatment decisions in patients with COVID-19.