Healthcare Providers and Payers
COVID-19 Serology (Antibody) Test
What does Labcorp offer for COVID-19 antibody testing?
Labcorp offers testing for antibodies against either the spike (S) or nucleocapsid (N) proteins of the SARS-CoV-2 virus.
What is the difference in the spike and nucleocapsid proteins?
Antibodies against the SARS-CoV-2 viral spike protein have been shown to have neutralizing effects.1-3 Current vaccines have been developed to elicit antibodies to the spike protein. Labcorp offers both semi-quantitative and qualitative options for testing for spike protein antibodies.
Use our test selection guide for physicians to understand which test to order for your patient.
Who can be tested?
Those who have previously been actively infected by the SARS-CoV-2 virus and do not currently have symptoms or have received a vaccine for COVID-19.
Can semi-quantitative COVID-19 antibody test be used to track antibody levels overtime?
On May 19, 2021, the FDA issued a safety communication reiterating that “antibody testing should not be used to evaluate a person’s level of immunity or protection from COVID-19 at any time, and especially after the person received a COVID-19 vaccination.”4 Currently authorized SARS-CoV-2 antibody tests, including the SARS-CoV-2 Semi-Quantitative Total Antibody assay (164090), have not been evaluated to assess the level of protection provided by an immune response to COVID-19 vaccination. Additionally, the components of a protective immune response against infection or re-infection with SARS-CoV-2 have not been fully characterized (e.g., antibody, T cell, etc.). Clinical trials and other studies are underway to elucidate the correlates of immunity to SARS-CoV-2.
Effective March 28, 2022 Labcorp expanded the reporting range of results for test number 164090 SARS-CoV-2 Semi-Quantitative Total Antibody, Spike. Results previously reported for this assay were 0.8-2500 U/mL with higher values reported as >2500 U/mL. With the addition of an automated dilution, we are now able to report result 0.8-25000 U/mL with higher values reported as >25000 U/mL. This change does not impact previously reported results; it just increases the numerical values above 2500 U/mL that we are able to report.
Labcorp antibody result reports will continue to include a comment indicating that the antibody level that correlates with immunity has not yet been determined. If antibody test results are interpreted incorrectly, people may take fewer precautions against SARS-CoV-2, which may result in increased risk of infection and spread of the virus. Please refer to the FDA website for further guidance around antibody testing recommendations.
Sample
Serum collected by venipuncture
Labcorp Test Number
- Physicians can order SARS-CoV-2 Semi-Quantitative Total Antibody 164090
- Values generated with this assay cannot be used to determine whether or not an individual has developed protective immunity against infection and cannot be directly compared to other assays until a universal standard is established for assay calibration.
- Physicians can order SARS-CoV-2 Antibodies, Nucleocapsid 164068
- This assay will not detect antibodies elicited by currently available SARS-CoV-2 vaccines.
- Physicians can order SARS-CoV-2 Antibody, IgG, Spike 164055
Where are samples collected?
- At a hospital or healthcare provider office
- At a Labcorp location
Receiving Results
- The average delivery of test results is 1-3 days from the date of specimen pickup.
- Delivered to the ordering physician's EMR or Labcorp Link™
- Labcorp does not flag antibody results, as the presence or absence of antibodies alone should not be used to diagnose active infection. Additionally, the presence of antibodies may be associated with immunity or vaccine response which would not be considered abnormal.
What is Semi-Quantitative COVID-19 Testing?
SARS-CoV-2 Virus
Spike (S): Antibodies to the spike protein are produced after vaccination1-3
Nucleocapsid (N): Antibodies to Nucleocapsid identify individuals who have had a recent or prior COVID-19 infection, but are not useful for detecting antibodies elicited by currently available SARS-CoV-2 vaccines.
Additional Information
COVID-19 Antibody Test Selection Guide
Test Name |
SARS-CoV-2 Semi-Quantitative Total Antibody* |
SARS-CoV-2 Antibodies, Nucleocapsid* |
SARS-CoV-2 Antibodies, IgG, Spike* |
|---|---|---|---|
| Test Number |
164090 | 164068 | 164055 |
| Intended Use |
Semi-quantitative detection of high affinity antibodies to the receptor binding domain (RBD) of the spike (S) protein of SARS-CoV-2. Intended for use as an aid in identifying individuals with an adaptive immune response to SARS-CoV-2 indicating recent or prior infection. This assay also can be used to detect antibody responses induced by currently available SARS-CoV-2 vaccines. | Qualitative detection of high affinity antibodies to the nucleocapsid (N) protein of SARS-CoV-2. Intended for use as an aid in identifying individuals with an adaptive immune response to SARS-CoV-2 indicating recent or prior infection. This assay can be used to differentiate between antibodies elicited due to natural infection versus vaccination. | Qualitative detection of IgG antibodies to the spike protein (S1/S2) of SARS-CoV-2. Intended for use as an aid in identifying individuals with an adaptive immune response to SARS-CoV-2 indicating recent or prior infection. This assay also can be used to detect antibody responses induced by currently available SARS-CoV-2 vaccines. |
| Additional Limitations |
Values generated with this assay cannot be used to determine whether or not an individual has developed protective immunity against infection and cannot be directly compared to other assays until a universal standard is established for assay calibration. Results from this test should not be used as the sole basis to diagnose or exclude active SARS-CoV-2 infection | This assay will not detect antibodies elicited by currently available SARS-CoV-2 vaccines. | Results from this test should not be used as the sole basis to diagnose or exclude active SARS-CoV-2 infection. |
Test Name:
SARS-CoV-2 Semi-Quantitative Total Antibody |
|---|
| Test Number: 164090 |
| Intended Use: Semi-quantitative detection of high affinity antibodies to the receptor binding domain (RBD) of the spike (S) protein of SARS-CoV-2. Intended for use as an aid in identifying individuals with an adaptive immune response to SARS-CoV-2 indicating recent or prior infection or vaccination. |
| AdditionalLimitations Values generated with this assay cannot be used to determine whether or not an individual has developed protective immunity against infection and cannot be directly compared to other assays until a universal standard is established for assay calibration. |
Test Name:
SARS-CoV-2 Antibodies, Nucleocapsid |
|---|
| Test Number: 164068 |
| Intended Use: Qualitative detection of high affinity antibodies to the nucleocapsid (N) protein of SARS-CoV-2. Intended for use as an aid in identifying individuals with an adaptive immune response to SARS-CoV-2 indicating recent or prior infection. Intended for use as an aid in identifying individuals with an adaptive immune response to SARS-CoV-2 indicating recent or prior infection. This assay can be used to differentiate between antibodies elicited due to natural infection versus vaccination. |
| AdditionalLimitations This assay will not detect antibodies elicited by currently available SARS-CoV-2 vaccines. |
Test Name:
SARS-CoV-2 Antibodies, IgG, Spike |
|---|
| Test Number: 164055 |
| Intended Use: Qualitative detection of IgG antibodies to the spike protein (S1/S2) of SARS-CoV-2. Intended for use as an aid in identifying individuals with an adaptive immune response to SARS-CoV-2 indicating recent or prior infection or vaccination. |
Considerations
- Negative antibody results in persons collected earlier than 21 days after symptom onset may be negative due to the kinetics of seroconversion, specifically, some patients will not have measurable antibody until more than 21 days after symptom onset.
- Results from antibody tests should not be used to diagnose active SARS-CoV-2 infection or to guide quarantine/isolation/PPE decisions.
- Conclusions about protective immunity to infection cannot be made on the basis of the results provided because the mechanisms of protective immunity against SARS-CoV-2 are not yet defined.
- Vendors are providing regular updates in regards to the ability of their assays to detect antibodies to new strains of the virus as they arise. To date, the assays in use detect the noted antibodies against the known circulating strains of SARS-CoV-2.
- Testing for antibodies induced by vaccination should be performed at least two weeks after the second vaccine dose.
References
- Zost SJ, Gilchuk P, Case JB, et al. Potently neutralizing and protective human antibodies against SARS-CoV-2. Nature. 2020;584(7821):443-449. doi:10.1038/s41586-020-2548-6.
- Seydoux E, Homad LJ, MacCamy AJ, et al. Characterization of Neutralizing Antibodies from a SARS-CoV-2 Infected Individual. Immunology; 2020. doi:10.1101/2020.05.12.091298.
- Ju B, Zhang Q, Ge J, et al. Human neutralizing antibodies elicited by SARS-CoV-2 infection. Nature. 2020;584(7819):115-119. doi:10.1038/s41586-020-2380-z
*Labcorp is providing serology testing based on tests from various manufacturers. These tests have not been FDA cleared or approved. The tests have been authorized by the FDA under an emergency use authorization for use by authorized laboratories. These tests have been authorized only for the detection of antibodies against SARS-CoV-2, and not for any other viruses or pathogens. These tests are only authorized for the duration of the declaration that circumstances exist justifying the authorization of emergency use of in vitro diagnostics for detection and/or diagnosis of COVID-19 under Section 564(b)(1) of the Act, 21 U.S.C. § 360bbb-3(b)(1), unless the authorization is terminated or revoked sooner.
COVID-19 Information and Resources
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