Test Catalog

Test Id : FSAR2

SARS-CoV-2 Neutralizing Antibody

Useful For
Suggests clinical disorders or settings where the test may be helpful

Detection of specific neutralizing antibodies capable of inhibiting SARS-CoV-2-virus.

Method Name
A short description of the method used to perform the test

Virus Neutralizing Antibody Test

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

SARS-CoV-2 Neutralizing Antibody

Lists additional common names for a test, as an aid in searching






Specimen Type
Describes the specimen type validated for testing


Ordering Guidance

Molecular testing is recommended for diagnosis of coronavirus disease 2019 (COVID-19) in symptomatic patients.

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions: Draw blood in a serum gel tube(s), plain red-top tube(s) is acceptable. Centrifuge and aliquot serum; send one aliquot. DO NOT heat-inactivate. Ship 1 mL serum in a plastic vial, frozen.

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

0.2 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross Hemolysis Reject
Gross Lipemia Reject
Gross Icterus Reject
Other NA

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Serum Frozen (preferred) 30 days
Refrigerated 72 hours
Ambient 24 hours

Useful For
Suggests clinical disorders or settings where the test may be helpful

Detection of specific neutralizing antibodies capable of inhibiting SARS-CoV-2-virus.

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a positive-sense, single-stranded RNA virus that causes coronavirus disease 2019 (COVID-19). Like other coronaviruses that infect humans, SARS-CoV-2 can cause both upper and lower respiratory tract infection. Symptoms can range from mild (ie, the common cold) to severe (ie, pneumonia) in both healthy and immunocompromised patients. SARS-CoV-2 transmission occurs primarily via respiratory droplets. During the early stages of COVID-19, symptoms maybe nonspecific and resemble other common respiratory tract infections, such as influenza. The incubation period for COVID-19 ranges from 3 to 14 days. Typically, immunocompetent individuals with COVID-19 develop detectable antibodies against SARS-CoV-2 approximately 8 to 11 days following onset of symptoms or vaccination. Patients tested prior to this time may be negative for SARS-CoV-2 antibodies.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

22 - 20,862 IU/mL

Provides information to assist in interpretation of the test results


POSITIVE: Neutralizing antibodies recognizing SARS-CoV-2 were detected in the blood at a level higher than the test threshold of 22 IU/mL. Results suggest prior infection with SARS-CoV-2 or vaccination against SARS-CoV-2.


NEGATIVE: Neutralizing antibody titer is below the test threshold of 22 IU/mL. Negative results may occur in samples collected too soon following infection or immunization, in immunosuppressed patients, or in individuals with  waning immunity.


BORDERLINE: No determination regarding the titer of neutralizing antibodies can be made. Borderline samples have either very low antibody titers or are negative for antibodies that neutralize SARS-CoV-2.



Titer values represent the level of neutralizing antibodies present in a blood sample. IMMUNO-COV titers have been calibrated to World Health Organization International Units per milliliter (IU/mL). Current scientific literature describes the degree of protection from COVID-19 conferred by different neutralizing antibody titers. Please refer to the Imanis website for the most up to date information: www.imanis-immunocov.com.


Note: Before October 2021, titers were reported in IMMUNO-COV VNT units. VNT and WHO IU/mL units are comparable. Multiply VNT result by 0.6954 to get equivalent WHO IU/mL value. Multiply WHO IU/mL result by 1.4380 to get equivalent VNT value.



This test was performed in the Imanis CLIA laboratory as a high complexity laboratory developed test. The test quantitatively measures the level (titer) of antibodies in a blood sample capable of blocking a live SARS-CoV-2 mimic virus from infecting Vero-ACE2 cells. The test limit of detection (LOD) is 22 IU/mL. The test upper limit of quantitation is 20,862.


 More detailed information about the test is available at the Imanis website: www.imanis-immunocov.com or in the following reference: Vandergaast et al. (2021) mSphere 6: e0017021. doi: 10.1128/mSphere.00170-21.



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Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Negative results do not rule out SARS-CoV-2 infection, particularly in those who have been in contact with the virus. Follow-up testing with a molecular diagnostic should be considered to rule out infection in these individuals.

Results from antibody testing should not be used as the sole basis to diagnose or exclude SARS-CoV-2 infection or to inform infection status.

Positive results may be due to past or present infection with non-SARS-CoV-2 coronavirus strains, such as coronavirus HKU1, NL63, OC63 or 229E.

Method Description
Describes how the test is performed and provides a method-specific reference

The Neutralizing Antibody Assay is a functional assay that detects the presence of specific neutralizing antibodies capable of inhibiting VSV-SARS2-Fluc infection. Vero cells (African green monkey-derived kidney epithelial cells) that have been stably transduced to overexpress angiotensin converting enzyme 2 (ACE2) are infected with a virus displaying the SARS-CoV-2 spike glycoprotein on its surface and encoding the same SARS-CoV-2 spike glycoprotein and a firefly luciferase (Fluc) reporter in its genome.  When this virus infects the Vero cells, the cells begin to produce firefly luciferase. A luciferase substrate is then added to assay plates to allow for a luminescence readout, wherein total luminescence (relative light units, RLU) corresponds to the extent of virus infection. The ability of antibodies in human serum or plasma to block infection of Vero-ACE2 cells by VSV-SARS2-Fluc, and thereby to prevent luciferase expression serves as a proxy readout for antibodies capable of neutralizing SARS-CoV-2 infection.

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Friday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

9 to 11 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test

Imanis Life Sciences

Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

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  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test was developed, and its performance characteristics determined by Imanis Life Sciences, LLC in a manner consistent with CLIA requirements. This test has not been reviewed, cleared, or approved by the U.S. Food and Drug Administration.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.


LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
FSAR2 SARS-CoV-2 Neutralizing Antibody 95410-7
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
FSAR2 SARS-CoV-2 Neutralizing Antibody 95410-7

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports