InBios SCoV-2 Detect IgG ELISA Kit Instructions

SCV-2 Detect™ IgG ELISA
Instructions for Use For Emergency Use Authorization (EUA) Only
For In Vitro Diagnostic (IVD) Use
Rx Only
For prescription use only

INTENDED USE

The SCoV-2 Detect™ IgG ELISA is an in vitro diagnostic test for the qualitative detection of IgG antibodies to SARS-CoV-2 in human serum or plasma (dipotassium EDTA) run manually or using the Dynex DSX ® Automated ELISA System.

The SCoV-2 Detect™ IgG ELISA is intended as an aid in identifying individuals with an adaptive immune response to SARS-CoV-2, indicating recent or prior infection. At this time, it is unknown for how long antibodies persist following infection and if the presence of antibodies confers protective immunity. The SCoV-2 Detect™ IgG ELISA should not be used to diagnose or exclude acute SARS-CoV-2 infection. Testing is limited to laboratories certified under the Clinical Laboratory Improvement Amendments of 1988 (CLIA), 42 U.S.C. §263a, that meet the requirements to perform moderate (automated method) or high (manual and automated method) complexity tests.

Results are for the detection of IgG SARS-CoV-2 antibodies. IgG antibodies to SARS-CoV-2 are generally detectable in blood several days after initial infection, although the duration of time antibodies are present post-infection is not well characterized. Individuals may have detectable virus present for several weeks following seroconversion.

Laboratories within the United States and its territories are required to report all results to the appropriate public health authorities.

Negative results do not preclude acute SARS-CoV-2 infection. If the acute infection is suspected, direct testing\ for SARS-CoV-2 is necessary.

False-positive results for SCoV-2 Detect™ IgG ELISA may occur due to cross- reactivity from pre-existing antibodies or other possible causes.

The SCoV-2 Detect™ IgG ELISA is only for use under the Food and Drug Administration Emergency Use Authorization (EUA).

SUMMARY AND EXPLANATION OF THE TEST

The novel coronavirus, SARS-CoV-2 (the causative agent of COVID-19), has been responsible for the pandemic of pneumonia-like symptoms and associated deaths from late 2019 and into 2020. The detection of the initial outbreak in the Hubei Province of China and the subsequent need for an effective diagnosis was quickly described (Li et al., 2020; Wu et al., 2020; Zhou et al., 2020).

It has been reported that PCR-confirmed SARS-CoV2 positive patients may seroconvert and develop antibodies against SARS-CoV-2 antigens anywhere from 6-21 days after the onset of clinical symptoms (Okba et al., 2020) The specific and reliable detection of human IgG antibodies to SARS-CoV-2 remains a key method to monitor infections, to effect contact tracing, and for zero surveillance (Okba et al., 2020).

The SCoV-2 Detect™ IgG ELISA is a qualitative immunoassay for the detection of IgG antibodies targeting SARS-CoV-2 related antigens.

PRINCIPLE OF THE TEST

The SCoV-2 Detect™ IgG ELISA is a qualitative indirect ELISA for the detection of IgG antibodies targeting epitopes derived from SARS-CoV-2. Diluted serum or plasma specimens are added to antigen-coated wells and incubated. After incubation and washing, human antibodies targeting SARSCoV-2 antigens remain bound to the plate surface. A secondary antibody conjugated to horseradish peroxidase (HRP) targeting human IgG is then added to each well. After incubation, the ELISA wells are washed once again before a tetramethylbenzidine (TMB) substrate is added. An acidic stopping solution is finally used to stop the reaction and the degree of enzymatic turnover of the substrate is determined by absorbance measurement at 450 nanometers.

Positive, Negative, and Cut-Off Controls are provided to ensure the integrity of the test and to determine the assay-specific threshold. Up to 90 specimens may be evaluated with each kit (as the controls are run in duplicate). The entire procedure takes approximately 1 hour and 50 minutes once all samples are added to the plate.

KIT CONTENTS

Warning: Do not use any reagents where damage to the packaging has occurred.

The kit contains the following reagents:

1. SCOV-2 ANTIGEN COATED MICROTITER STRIPS FOR IGG: Strip holder in a resealable foil pouch, containing 96 polystyrene microtiter wells coated with SCoV-2 antigen in each well. Stable at 2-8°C until the expiration date.

2. SCOV-2 IGG NEGATIVE CONTROL: One vial, 50 µL. Negative serum. The Negative Control will aid in monitoring the integrity of the kit. Stable at 2-8°C until the expiration date.

3. SCOV-2 IGG POSITIVE CONTROL: One vial, 50 µL. Positive Control sample. The Positive Control will aid in monitoring the integrity of the kit. Stable at 2-8°C until the expiration date.

4. SCOV-2 IGG CUT-OFF CONTROL: One vial, 50 µL. Cut-Off Control sample. The Cut-Off Control will aid in monitoring the integrity of the kit and estimating the proper threshold to determine test sample status. Stable at 2-8°C until the expiration date.

5. SAMPLE DILUTION BUFFER FOR SCOV-2: Two bottles, 25 ml each, ready to use. Tris-HCl buffered solution (pH 7.2-7.6) with Tween 20 (0.05%), preservative (0.05% ProClin-300) and additives. The Sample Dilution Buffer will be used for the dilution of test samples and controls. Stable at 2-8°C until the expiration date.

6. 100X CONJUGATE FOR SCOV-2 IGG: One vial, 100 µL, containing horseradish peroxidase-labeled antibody in a Tris-based buffer with 0.03% – 0.05% ProClin-300. Stable at 2-8°C until the expiration date.

7. CONJUGATE DILUENT FOR SCOV-2: One bottle, 9 mL. This contains the diluent solution for the 100X Conjugate in a Tris-based buffer with 0.01% Thimerosal as a preservative. The 100X conjugate is diluted directly into this solution. The 100X conjugate should only be diluted into this solution immediately prior to running the assay. Unused diluted conjugate should be discarded. The conjugate diluent is stable at 2-8°C until the expiration date.

8. 10X WASH BUFFER: One bottle, 120 mL. 10X concentrated phosphate-buffered saline with Tween 20 (pH 6.8-7.0). Stable at 2-8°C until the expiration date.

9. LIQUID TMB SUBSTRATE: One bottle, 12mL, ready to use. Contains 3, 3’, 5, 5’- tetramethylbenzidine (TMB) and hydrogen peroxide in a citric acid-citrate buffer (pH 3.33.8). Stable at 2-8°C until the expiration date.
   Note: The substrate should always be stored in the light-protected bottle provided.

10. STOP SOLUTION: One bottle, 6mL, ready to use. 1N Sulfuric Acid. Used to stop the reaction. Stable at 2-8°C until the expiration date.
    Warning: Strong acid. Wear protective gloves, a mask, and safety glasses. Dispose of all materials according to all applicable safety rules and regulations.

MATERIALS AND EQUIPMENT ARE REQUIRED BUT NOT PROVIDED

The following materials and equipment are always required:

• Biological or high-grade water
• Appropriately sized beakers and stir bars
• 1-10 µL single-channel pipettors, 50-200 µL single- and multichannel pipettors

The following materials and equipment are required if the assay is being performed manually:

• ELISA spectrophotometer capable of absorbance measurement at 450 nm
• Vacuum pump
• Automatic plate washer
• 37°C incubator without CO2 supply or humidification
• Polypropylene tubes or 96 well dilution plates
• Parafilm or plastic plate cover
• Timer
• Vortex

The following equipment is required if the assay is being performed using the Dynex DSX ® automated ELISA system:

• Dynex DSX®
• Assay file: InBios SCoV-2 Detect IgG ELISA v1.asy (provided upon request)
• SCoV-2 DetectTM IgG ELISA DSX Extra Components (Catalog No. CVG-DSX)
• Deep-well strips (Dynex Part No. 62910)
• Sample tips (Dynex Part No. 65910)
• Reagent tips (Dynex Part No. 65920)
• Deep-well microplate (Dynex Part No. 65930)
• Reagent tubes, 25 mL (Dynex Part No. 65950)

WARNINGS AND PRECAUTIONS

• For in vitro diagnostic use under Emergency Use Authorization (EUA) only. For prescription use only. A thorough understanding of this package insert is necessary for the successful use of the product. Reliable results will only be obtained by using precise laboratory techniques and accurately following the package insert.
• This product has not been FDA cleared or approved but has been authorized for emergency use by FDA under a EUA for use by authorized laboratories.
• This product has been authorized only for detecting the presence of IgG antibodies to SARS-CoV-2, not for any other viruses or pathogens.
• The emergency use of this product is only authorized for the duration of the declaration that circumstances exist justifying the authorization of emergency use of in vitro diagnostics for the detection and/or diagnosis of COVID-19 under Section 564(g)(2)(C) of the Act (21 U.S.C. § 360bbb-3(g)(2)(C) unless the declaration is terminated or authorization is revoked sooner.
• Laboratories within the United States and its territories are required to report all results to the appropriate public health authorities.
• Follow standard precautions. All patient specimens and positive controls should be considered potentially infectious and handled in accordance with good laboratory procedures.

SAFETY PRECAUTIONS

• All human source materials used in the preparation of the negative control have tested negative for antibodies to HIV 1&2, Hepatitis C, and Hepatitis B surface antigen. However, no test method can ensure 100% efficiency. Therefore, all human controls and antigens should be handled as potentially infectious material. The Centers for Disease Control and Prevention and the National Institutes of Health recommend that potentially infectious agents be handled at the Biosafety Level 2.
• Dispose of hazardous or biologically contaminated materials according to the practices of your institution. Discard all materials in a safe and acceptable manner and in compliance with prevailing regulatory requirements.
• Wear protective clothing, eye protection, and disposable gloves while performing the assay. Wash hands thoroughly afterward.
• Do not eat, drink, smoke, or apply cosmetics in the laboratory where immunodiagnostic materials are being handled.
• Do not pipette by mouth.
• Refer to Dynex DSX® Automated ELISA System Operator’s Manual for machine-related safety precautions, if applicable

TECHNICAL PRECAUTIONS

• This test must be performed on human serum or plasma (dipotassium EDTA) only. The use of whole blood, plasma with other anticoagulants, or other specimen matrices has not been validated.
• Do not mix various lots of any kit component within an individual assay.
• All reagents must be equilibrated to room temperature (15-25°C) before commencing the assay. The assay will be affected by temperature changes.
• Avoid repeated freezing and thawing of the serum or plasma specimens to be evaluated.
• Dispense reagents directly from bottles using clean pipette tips. Transferring reagents may result in contamination.
• Unused microtiter wells must be resealed immediately in the zip lock foil pouch with the desiccant provided. Failure to do so may cause erroneous results with those unused microwells.
• Do not use any component beyond the expiration date shown on its label.
• Avoid exposure of the reagents to excessive heat or direct sunlight during storage and incubation.
• Some reagents may form a slight precipitate, mix gently before use.
• Incomplete washing will adversely affect the outcome and assay performance.
• To minimize potential assay drift due to variation in the substrate incubation time, care should be taken to add the stop solution into the wells in the same order and speed used to add the TMB solution.
• Avoid microbial contamination of reagents.
• Avoid contamination of the TMB Substrate Solution with the Conjugate Solution. The TMB Substrate Solution should be clear in color; a blue color change prior to use may indicate contamination has occurred.
• Use a clean disposable pipette tip for each reagent, standard, control, or specimen.
• If the assay is run manually, cover the working area with disposable absorbent paper.
• Refer to Dynex DSX ® Automated ELISA System Operator’s Manual for machine-related technical precautions, if applicable.

WARNING: POTENTIAL BIOHAZARDOUS MATERIAL

This kit contains reagents made with human serum or plasma. The serum or plasma used has been heat-inactivated unless otherwise stated. Handle all sera, plasma, and kits used as if they contain infectious agents. Observe established precautions against microbiological hazards while performing all procedures and follow the standard procedures for proper disposal of specimens.

CHEMICAL HAZARD

Safety Data Sheets (SDSs) are available for all components of this kit. Review all appropriate SDSs before performing this assay. Avoid all contact between hands and eyes or mucous membranes during testing. If contact does occur, consult the applicable SDS for appropriate treatment.

SPECIMEN COLLECTION AND PREPARATION

• Only human serum or plasma (dipotassium EDTA) should be used for this assay, and the usual precautions for venipuncture should be observed.
• To obtain serum, blood obtained by venipuncture without anticoagulant should be allowed to clot at room temperature (20-25°C) for 30 to 60 minutes and then centrifuged according to the Clinical and Laboratory Standards Institute (CLSI Approved Guideline – Procedures for the Handling and Processing of Blood Specimens for Common Laboratory Tests; GP44).
• Testing should be performed as soon as possible after collection. Do not leave sera or plasma at room temperature for prolonged periods. Separated serum or plasma should remain at 20-25°C for no longer than 8 hours. If assays are not completed within 8 hours, samples should be refrigerated at 2-8°C. If assays are not completed within 48 hours, or the separated serum or plasma is to be stored beyond 48 hours, serum or plasma should be frozen at or below -20°C.
• Avoid repeated freezing and thawing of samples more than four times as this can cause analyte deterioration. Frost-free freezers are not suitable for sample storage. Frozen samples should be thawed to room temperature and mixed thoroughly by gentle swirling or inversion prior to use. Always quick spin before use.
• If sera or plasma are to be shipped, they should be packed in compliance with Federal Regulations covering the transportation of infectious agents.
• Do not use sera or plasma if any indication of microbial growth is observed.

TEST PROCEDURE

CAUTION: The test procedure must be strictly followed. Any deviations from the procedure may produce erroneous results. Bring all reagents and specimens to room temperature (~25°C) before use. Thoroughly mix the reagents and samples before use by gentle inversion.
NOTE: For long-term storage, serum or plasma samples should not be repeatedly thawed and frozen more than four times. Samples should be further divided into small aliquots and stored at -20°C or below.

This assay is intended to be performed manually or using the Dynex DSX® automated ELISA system only. Plate washing must be performed using a properly calibrated automated plate washer. This kit has not been optimized by InBios for use with any other automated ELISA processing systems.

PREPARATION OF REAGENTS

Note: The following procedure applies regardless of whether the assay is being performed manually or using the Dynex DSX

• Preparation of 1X Wash Buffer
  Dilute the 10X Wash Buffer to 1X using Biological or High-Grade Water. To prepare a 1X Wash Buffer solution, mix 120 mL 10X Wash Buffer with 1080 mL distilled (or deionized) water. Mix thoroughly to ensure that any precipitate is dissolved and that the solution is uniform. Once diluted to 1X, the solution can be stored at room temperature for up to 6 months. Properly label the 1X Wash Buffer solution and carefully note the expiration date on the label. Check for contamination prior to use. Discard if contamination is suspected.

• Microtiter Strip Wells
  Select the number of coated wells required for the assay. The remaining unused wells should be repackaged immediately with the supplied desiccant and stored at 2-8°C until ready to use or expire.

• Preparation of Conjugate Solution
  Add 90 µL of 100X Conjugate for SCoV-2 IgG directly to the 9 mL bottle of Conjugate Diluent for SCoV-2 (1 part: 100 parts). Alternatively, use a clean pipette to remove the required volume of Conjugate Diluent and add the necessary volume of 100X Conjugate for SCoV-2 ELISA into a clean polypropylene test tube or reagent tube in order to maintain the 1:100 ratio. Mix by inverting the solution several times. This conjugate solution should be prepared immediately prior to running the assay and discarded immediately after use in the assay.

MANUAL OPERATION

Assay Procedure:

1. Positive, negative, and cut-off controls should be assayed in duplicate (and run on every plate, each time an assay is performed). Unknown serum or plasma samples may be tested in singlicate or in duplicate. Unknown serum or plasma samples tested in singlicate may require retesting as indicated in the Interpretation of Results section. Up to ninety test specimens can be tested in singlicate with an entire plate. Immediately place any unused ELISA plate wells back into the original foil packaging with the provided desiccant, properly seal and store at 2-8°C. 2. Dilute each control and each test specimen 1:100 by adding 4 µL of sample to 396 µL of Sample Dilution Buffer for SCoV-

2. Dilute samples into a dedicated sample dilution block or an appropriately sized tube.

3. Add 50 µL of the 1:100 diluted controls and test specimens onto the appropriate locations in the SCoV-2 Antigen Coated Microtiter Strip plate (ELISA plate). Note and record the locations of all controls and test samples in the ELISA plate wells.

4. Cover the top of the plate with parafilm (or a plastic plate cover) and remove any excess parafilm from the edges of the plate.
   Note: This is to make sure the temperature distribution is evenly spread out in all wells from the bottom and sides; any extra parafilm can be cut off once the top is sealed to block evaporation.
   CORRECT METHOD
   Note: Do not stack plates on top of each other. They should be spread out as a single layer. This is very important for even temperature distribution. Do not use CO2 or other gases. Do not place plates in contact with any wet substances such as wet paper towels etc.

5. Cover the plate with parafilm or a plastic plate cover and incubate the plate(s) at 37°C for 1 hour in an incubator.

6. After the incubation, wash the plate 6 times with an automatic plate washer using 1X Wash Buffer. Use 300 µL per well in each wash cycle.

7. Prepare the Conjugate Solution (90 µL of 100X Conjugate: 9 mL of Conjugate Diluent) and add 50 µL per well of this Conjugate Solution into all wells using a multi-channel pipettor. Discard the remaining Conjugate Solution.

8. Cover the plate with parafilm or a plastic plate cover and incubate the plate(s) at 37°C for 30 minutes in an incubator.

9. After the incubation, wash the plate 6 times with the automatic plate washer using 1X Wash Buffer.

10. Add 75 µL per well of Liquid TMB substrate into all wells using a multi-channel pipettor.

11. Incubate the plate, uncovered at room temperature in the dark, for 20 minutes.

12. Add 50 µL per well of Stop Solution into all appropriate wells using a multichannel pipetter. Make sure to add the Stop Solution in the same order and at approximately the same speed at which the TMB was applied. (Note: As the TMB substrate produces an enzymatic reaction with the HRP-conjugate, it is critical this incubation time point is followed as closely as possible). Let the plate stand, uncovered at room temperature, for 1 minute.

13. Read the optical density at 450 nm (OD450) with a microplate reader. DO NOT USE A REFERENCE WAVELENGTH. DO NOT SUBTRACT OR NORMALIZE ANY BLANK VALUES OR WELLS.

14. Record the raw OD450 and evaluate the sample status as indicated in the Quality Control and Interpretations of Results sections.

DSX ® OPERATION

NOTE: All DSX ® operators must have appropriate machine training prior to performing this procedure. Refer to the Dynex DSX ® Operator’s Manual or Training Guide for additional details on setting up, operating, and troubleshooting the DSX ® automated system.
NOTE: Avoid light exposure to the TMB reagent when possible. Add TMB reagent to the machine board only when prompted and close the machine cover when prompted by the machine.

Assay Procedure:

1. Turn on the Dynex DSX ® machine and connect to the Revelations software (version 6.28).

2. Run start-up assays to ensure the plate washer is performing as anticipated, as recommended by the DSX ® Training Guide. Consult the manual or contact Dynex Technologies for technical assistance if any abnormal dispensing or aspirating is observed. Do not continue with the following steps until uniform dispensing and aspirating are achieved.

3. Start a new worklist and choose the relevant sample batch selection.

4. Load assay file “InBios SCoV-2 Detect IgG ELISA v1.asy” and select the number of samples to be run. A maximum of 90 samples (plus controls) can be run per plate.

5. Fill in relevant sample identification numbers.

6. Start assay and follow assay prompts for loading and positioning of sample caddy, all kit reagents, and any required consumables. Enter kit lot number and plate identifiers as desired. Plate barcode scanning is not applicable for this assay.
   Note: 1X Wash Buffer and the Conjugate Solution must be prepared as described in the “Preparation of Reagents” section prior to adding the reagents to the prompted position. Additional controls and Sample Dilution Buffer volumes will be required from what is provided in the SCoV-2 Detect TM IgG ELISA and can be ordered using Catalog No. CVG-DSX.

7. Refer to “MANUAL OPERATION” for assay steps, relevant volumes, and incubation time points (with tolerances). If any error messages arise due to out-of-tolerance incubation time points, the run must be disregarded and considered invalid.

8. Once the run is complete and the plate has been read, the OD450 readings will appear as a report on Revelations and will also save onto a file. This file will be saved as [plateID].txt in the “Text” folder under the Revelations directory.

9. Refer to subsequent sections for quality control and results analysis.

QUALITY CONTROL

Each kit contains positive, negative, and cut-off controls. The negative and positive controls are intended to monitor for substantial reagent failure. The positive control will not ensure precision at the assay cut-off. The test is invalid and must be repeated if the control samples do not meet the specifications. If the test is invalid, the results cannot be used. Quality Control (QC) requirements must be performed in conformance with local, state, and/or federal regulations or accreditation requirements and your laboratory’s standard Quality Control procedures. It is recommended that the user refers to CLSI C24 and 42 CFR 493.1256 for guidance on appropriate QC practices. The results below are given strictly for guidance purposes only and applicable for spectrophotometric readings only.

First, calculate the mean (average) negative, positive and cut-off control raw OD450 values as shown in the following examples.

Example 1: SCoV-2 Negative Control
OD450

Average Positive Control = 3.499 ÷ 2 = 1.7495

Example 3: SCoV-2 Cut-Off Control
OD450

Average Positive Control = 3.499 ÷ 2 = 1.7495

Example 3: SCoV-2 Cut-Off Control
OD450

Average Cut-Off Control = 1.284 ÷ 2 = 0.642

Finally, verify that the quality control requirements, listed in the table below, are fulfilled.

Quality Control Requirements

Summary: The results in the table above must be obtained for the assay to be considered valid. Non-fulfillment of these criteria is an indication of deterioration of reagents or an error in the test procedure and the assay must be repeated.

The assay cut-off value was determined by screening a large number (>100) of normal human serum (NHS) samples that were collected prior to the COVID-19 outbreak (~November 2019). The cut-off selection was performed by estimating the mean of the negative specimens plus three (3) standard deviations.

The status of the unknown sample is determined by first calculating the cut- off of the assay (shown above in Example 3), followed by calculating the ratio of the optical density (OD450) divided by the cut-off.

Calculate Immunological Status Ratio (ISR): The immunological status ratio (ISR) is calculated from the ratio of the optical density (OD) obtained with the test sample divided by the calculated Cut-Off Value. Calculate the ISR for each test sample. If unknown samples were tested in duplicate, then calculate the average optical density (OD450) before dividing by cut-off to determine ISR.

Example 4: Calculate the ISR for a Sample

ISR Value = Raw OD ÷ Cut-Off Value
ISR Value = 1.321 ÷ 0.642 = 2.058

close to the cut-off (0.9 < ISR < 1.1) must be repeated in duplicate along with controls to verify the sample status. If the average ISR value from the repeat duplicate testing is ≥ 1, the sample should be considered positive for IgG antibodies to SCoV-2. If the average ISR value from the duplicate testing is < 1, the sample should be considered negative for IgG antibodies targeting SCoV-2.
≥ 1.1| Positive| Presence of detectable IgG antibodies targeting SCoV-2 antigen.
≤ 0.9| Negative| No detectable IgG antibodies targeting SCoV-2 antigen were found. The result does not rule out the possibility of SARS-CoV-2 infection.

LIMITATIONS

• The SCoV-2 Detect™ IgG ELISA is authorized for use manually and with the Dynex DSX® Automated ELISA System.
• The assay performance characteristics have not been established for visual result determination.
• The assay performance characteristics have not been established for matrices other than serum or plasma (dipotassium EDTA).
• The assay should not be used to diagnose or exclude acute infection. Results are not intended to be used as the sole basis for patient management decisions.
• A positive result may not indicate a previous SARS-CoV-2 infection. Consider other information, including clinical history and local disease prevalence, in assessing the need for a second but different serology test to confirm an immune response.
• A negative result for an individual subject indicates the absence of detectable anti-SARS-CoV-2 antibodies. Negative results do not preclude SARS-CoV-2 infection and should not be used as the sole basis for patient management decisions. A negative result can occur if the quantity of the anti-SARS-CoV-2 antibodies present in the specimen is below the detection limits of the assay, or the antibodies that are detected are not present during the stage of disease in which a sample is collected.
• It is not known at this time if the presence of antibodies to SARS-CoV-2 confers immunity to infection.
• False-positive results due to cross-reactivity with antibodies to other coronaviruses can occur.
• Assay performance characteristics have not been established for testing cord blood, for testing neonates, for prenatal screening, or for general population screening.
• Samples that are hemolyzed should be avoided for analysis with this assay.
• Results from immunosuppressed patients must be interpreted with caution.
• Assay results should be interpreted only in the context of other laboratory findings and the total clinical status of the patient.
• The performance of this device has not been established in individuals that have received a COVID-19 vaccine. The clinical significance of a positive or negative antibody result following COVID-19 vaccination has not been established, and the result from this assay should not be interpreted as an indication of degree of protection from infection after vaccination.
• The performance of this test was established based on the evaluation of a limited number of clinical specimens collected between April 2020 and June 2020 from within the USA. The clinical performance has not been established in all circulating variants but is anticipated to be reflective of the prevalent variants in circulation at the time and location of the clinical evaluation. Performance at the time of testing may vary depending on the variants circulating, including newly emerging strains of SARS-CoV-2 and their prevalence, which change over time.

CONDITIONS OF AUTHORIZATION FOR THE LABORATORY

The SCoV-2 Detect™ IgG ELISA Letter of Authorization, along with the authorized Fact Sheet for Healthcare Providers, the authorized Fact Sheet for Patients, and authorized labeling are available on the FDA website: https://www.fda.gov/medical-devices/coronavirus-disease-2019-covid-19 -emergency-use-authorizationsmedical-devices/vitro-diagnostics-euas

Authorized laboratories using the ScoV-2 Detect™ IgG ELISA must adhere to the Conditions of Authorization indicated in the Letter of Authorization as listed below:

• Authorized laboratories using the SCoV-2 Detect™ IgG ELISA must include with test result reports, all authorized Fact Sheets. Under exigent circumstances, other appropriate methods for disseminating these Fact Sheets may be used, which may include mass media.
• Authorized laboratories using the SCoV-2 Detect™ IgG ELISA must use the product as outlined in the authorized labeling. Deviations from the authorized procedures, including the authorized instrument, authorized clinical specimen types, authorized control materials, authorized other ancillary reagents, and authorized materials required to use the product are not permitted.
• Authorized laboratories that receive the SCoV-2 Detect™ IgG ELISA must notify the relevant public health authorities of their intent to run the assay prior to initiating testing.
• Authorized laboratories using the SCoV-2 Detect™ IgG ELISA must have a process in place for reporting test results to healthcare providers and relevant public health authorities, as appropriate.
• Authorized laboratories must collect information on the performance of the SCoV-2 Detect™ IgG ELISA and report to DMD/OHT7-OIR/OPEQ/CDRH (via email: CDRH EUA Reporting@fda.hhs.gov) and InBios Technical Support (https://inbios.com/technical-support/) any suspected occurrence of false reactive or false non-reactive results and significant deviations from the established performance characteristics of the assay of which they become aware.
• All laboratory personnel using the SCoV-2 Detect™ IgG ELISA must be appropriately trained in immunoassay techniques and use appropriate laboratory and personal protective equipment when handling this kit, and use the SCoV-2 Detect™ IgG ELISA in accordance with the authorized labeling. All laboratory personnel using the assay must also be trained in and be familiar with the interpretation of results of the SCoV-2 Detect™ IgG ELISA.
• InBios International Inc., authorized distributor(s), and authorized laboratories using the SCoV-2 Detect™ IgG ELISA must ensure that any records associated with this EUA are maintained until otherwise notified by FDA. Such records will be made available to FDA for inspection upon request.

a The letter of authorization refers to, “Laboratories certified under the Clinical Laboratory Improvement Amendments of 1988 (CLIA), 42 U.S.C. §263a, that meet the requirements to perform moderate (automated method) or high (manual and automated methods) complexity tests“ as “authorized laboratories”.

PERFORMANCE CHARACTERISTICS

Clinical Evaluation
The positive percent agreement (PPA) of the SCoV-2 Detect TM IgG ELISA was estimated by testing a panel of serum specimens collected from 85 individuals who tested positive by SARS-CoV-2 PCR assay at an earlier time point. One or more samples were collected from each individual at various time points. Reactivity was correlated with elapsed days after symptoms onset, and results were analyzed using the first bleed per interval (i.e. ≤7, 8-14, ≥15 days post symptoms onset). Of the 111 specimens provided by the 85 subjects, 102 specimens tested reactive (positive) with the SCoV-2 Detect TM IgG ELISA.
Reactivity was correlated with elapsed days after symptoms onset.

Summary of results in relation to days post-onset of symptoms and PCR confirmation

Days post symptom onset| # PCR Positive at any time| SCoV-2 Detect TM IgG ELISA
---|---|---
# Positive results| PPA| 95%CI
≤7| 9| 5| 55.56%| 26.67% – 81.12%
8-14| 35| 31| 88.57%| 74.05% – 95.46%
≥15| 48| 47| 97.92%| 89.10% – 99.63%
unknown| 19| 19| 100%| 83.18%-100%

Overall positive percent agreement for the SCoV-2 DetectTM IgG ELISA

Positive Percent Agreement (PPA)| 91.89% (102/111)
95% CI: (85.31% – 95.68%)
---|---

*95% confidence interval calculated by Wilson method

The negative percent agreement (NPA) of the SCoV-2 Detect TM IgG ELISA was estimated by testing a panel of 95 normal human serum specimens. 94 of the 95 specimens tested non-reactive (negative) with the SCoV-2 Detect TM IgG ELISA.

Overall negative percent agreement for the SCoV-2 DetectTM IgG ELISA

Negative Percent Agreement (NPA)| 98.95% (94/95)
95% CI: (94.28% – 99.81%)
---|---

*95% confidence interval calculated by Wilson method.

Independent Clinical Agreement Validation
The SCoV-2 Detect™ IgG ELISA from InBios was tested on 2020-06-15 at the Frederick National Laboratory for Cancer Research (FNLCR) sponsored by the National Cancer Institute (NCI). The test was validated against a panel of previously frozen samples consisting of 30 SARS-CoV-2 antibody-positive serum samples and 80 antibody-negative serum and plasma samples. Each of the 30 antibody-positive samples were confirmed with a nucleic acid amplification test (NAAT) and IgG antibodies were confirmed to be present in all 30 samples. The presence of antibodies in the samples was confirmed by several orthogonal methods prior to testing with the SCoV-2 Detect™ IgG ELISA. The presence of IgG antibodies specifically was confirmed by one or more comparator methods. Antibody-positive samples were selected at different antibody titers.

All antibody-negative samples were collected prior to 2020 and include: i) Seventy (70) samples selected without regard to clinical status, “Negatives” and ii) Ten (10) samples selected from banked serum from HIV+ patients, “HIV+”. Testing was performed by one operator using one lot of the SCoV-2 Detect™ IgG ELISA. Confidence intervals for sensitivity and specificity were calculated per a score method described in CLSI EP12-A2 (2008).

For evaluation of cross-reactivity with HIV+, it was evaluated whether an increased false-positive rate among antibody-negative samples with HIV was statistically higher than the false positive rate among antibody-negative samples without HIV (for this, a confidence interval for the difference in false-positive rates was calculated per a score method described by Altman). The results and data analysis are shown in the tables below.

Summary Results

Summary Statistics

Cross-Reactivity (Analytical Specificity)
Cross-reactivity of the SCoV-2 Detect™ IgG ELISA Kit was evaluated by testing SARS-CoV-2 seronegative specimens from patients with antibodies to other viral infections and autoantibodies which could potentially cause false-positive results. One hundred eighty normal human serum (NHS) samples that were collected in the US prior to the COVID-19 outbreak (i.e. known negatives) were also tested. SCoV-2 Detect™ IgG ELISA demonstrates no cross-reactivity against IgG antibodies for influenza A, influenza B, hepatitis B, hepatitis C, human immunodeficiency, respiratory syncytial viruses, or anti-nuclear antibodies or human anti-mouse antibody.

Limited cross-reactivity was also observed with RF samples but did not correlate to RF levels. 180 of 180 NHS tested negative, for an observed specificity of 100%.

Reproducibility – Manual Operation
Reproducibility of the SCoV-2 Detect ™ IgG ELISA was evaluated by having three operators test the SCoV-2 Detect ™ IgG ELISA Kit on three different days (total of nine runs). All runs were performed by trained personnel at InBios International as per the kit’s instructions for use and the same kit lot was used in all runs. Each run included kit controls (positive, negative, and cut-off) and a seven-member serum panel comprised of positive, negative, and borderline samples. All kit controls and each panel member were tested in triplicate.

Each sample has been tested a total of 27 times. Percent agreement with expected values is shown below.

| Positive| Negative| **% Agreement with expected result [95% confidence interval]***
---|---|---|---
Panel 1 (negative)| 0| 27| 100% [87.54-100%]
Panel 2 (moderate positive)| 27| 0| 100% [87.54-100%]
Panel 3 (negative)| 0| 27| 100% [87.54-100%]
Panel 4 (negative)| 0| 27| 100% [87.54-100%]
Panel 5 (low positive)| 27| 0| 100% [87.54-100%]
Panel 6 (moderate positive)| 27| 0| 100% [87.54-100%]
Panel 7 (negative)| 0| 27| 100% [87.54-100%]

*95% confidence interval calculated by Wilson method.

Within-run, between-run, between-operator, and overall variability of immunological status ratios (ISRs) are summarized below. Because average values tended to be lower for the negative samples, the %CV tended to be higher, but % agreement with expected result remained high.

| Within-Run (Repeatability)| Between-Run| Between- Operator| Overall Reproducibility (Within-Laboratory)
---|---|---|---|---
Sample Description| Average Value| N| SD| %CV| SD| %CV| SD| %CV| SD| %CV
Panel 1| 0.469| 27| 0.022| 4.7%| 0.047| 9.9%| 0.230| 49.0%| 0.235| 50.2%
Panel 2| 4.834| 27| 0.142| 2.9%| 0.246| 5.1%| 0.540| 11.2%| 0.610| 12.6%
Panel 3| 0.503| 27| 0.031| 6.2%| 0.032| 6.3%| 0.217| 43.1%| 0.221| 44.0%
Panel 4| 0.559| 27| 0.033| 5.9%| 0.039| 7.1%| 0.202| 36.1%| 0.208| 37.2%
Panel 5| 1.424| 27| 0.084| 5.9%| 0.163| 11.4%| 0.201| 14.1%| 0.272| 19.1%
Panel 6| 3.365| 27| 0.168| 5.0%| 0.301| 8.9%| 0.401| 11.9%| 0.529| 15.7%
Panel 7| 0.532| 27| 0.060| 11.3%| 0.045| 8.5%| 0.228| 42.9%| 0.240| 45.1%

Reproducibility – DSX® Operation
Reproducibility of the SCoV-2 Detect™ IgG ELISA was evaluated by having one operator test the SCoV-2 Detect™ IgG ELISA Kit on five different days, with two runs performed per day (total of ten runs). All runs were performed on the Dynex DSX® machine as per the kit’s instructions for use and the same kit lot was used in all runs. Each run included kit controls (positive, negative, and cut-off) tested in duplicate and a four-member serum panel comprised of positive and negative samples tested in triplicate.

Panel members have tested a total of 30 times. Percent agreement with expected values is shown below.

| Positive| Negative| **% Agreement with expected result [95% confidence interval]***
---|---|---|---
Panel 1 (low positive)| 30| 0| 100% [88.7-100%]
Panel 2 (low positive)| 30| 0| 100% [88.7-100%]
Panel 3 (negative)| 0| 30| 100% [88.7-100%]
Panel 4 (negative)| 0| 30| 100% [88.7-100%]

Within-run, between-run, between-day, and overall variability of immunological status ratios (ISRs) are summarized below.

| Within-Run (Repeatability)| Between-Run| Between-Day| Overall Reproducibility (Within-Laboratory)
---|---|---|---|---
Sample Description| Average Value| N| SD| %CV| SD| %CV| SD| %CV| SD| %CV
Panel 1| 2.90| 30| 0.152| 5.2%| 0.331| 11.4%| 0.00| 0.0%| 0.364| 12.5%
Panel 2| 1.41| 30| 0.117| 8.3%| 0.200| 14.2%| 0.00| 0.0%| 0.232| 16.4%
Panel 3| 0.66| 30| 0.037| 5.6%| 0.096| 14.4%| 0.00| 0.0%| 0.103| 15.4%
Panel 4| 0.37| 30| 0.026| 6.9%| 0.046| 12.4%| 0.00| 0.0%| 0.053| 14.2%

Comparison of Manual vs. DSX® Operation
A panel of eighty-three (83) SARS-CoV-2 antibody-positive samples (neat or contrived) and thirty-eight (38) negative samples were tested on the SCoV-2 DetectTM IgG ELISA using both manual and DSX® operation. Antibody positive samples were selected such that reactivity ranged from highly negative to highly positive. Assays were run and results were interpreted as per the kit’s instructions for use. Using manual testing as the reference for sample characterization of each panel member, 76/83 positive samples were classified as positive under DSX® operation and 38/38 negative samples were classified as negative under DSX® operation. All seven samples that tested positive when run manually but negative when run on the DSX® were low positive samples with a maximum ISR of 1.58. The results of Passing-Bablok regression analysis using manual testing as the reference for sample characterization of each panel member produced a slope of 0.9482 and an intercept of

Interference
Potential interferents in human serum were tested at or above physiologically relevant levels to determine whether they could cause false positives or false negatives on SCoV-2 Detect ™ IgG ELISA Kit. Samples at different anti-SARS- CoV-2 IgG antibody concentrations were spiked with potential interfering substances, then tested in duplicates. No interference was observed for concentrations up to 10 mg/mL hemoglobin, 0.4 mg/mL bilirubin (conjugated or unconjugated), 15 mg/mL triglycerides, and 4 mg/mL cholesterol.
Blood-derived potential interferents, their normal concentrations in human blood and serum, and the concentrations tested in this study are shown below.

Interfering Substance| Normal concentration| Test concentration| Solvent
---|---|---|---
Hemoglobin| <0.01-0.05 mg/mL for serum, 110-180 mg/mL for whole blood| 10 mg/mL| Sample Dilution
Buffer (SDB)
Bilirubin (conjugated and unconjugated)| 0.002 – 0.01 mg/mL normal, >0.025 mg/mL jaundiced| 0.4 mg/mL| 0.1N NaOH
Triglycerides| <1.30-2.00 mg/mL| 15 mg/mL| Sample Dilution Buffer (SDB)
Cholesterol| 1.70-1.90 mg/mL normal, 2.80-3.20 mg/mL elevated| 4 mg/mL| Isopropyl alcohol (IPA)

Matrix Equivalency
Matrix sets from 5 individual donors were tested on SCoV-2 Detect TM IgG ELISA. Each matrix set consisted of paired serum and plasma with dipotassium EDTA anticoagulant. Contrived samples were generated at medium positive, low positive, and negative concentrations using the same dilutions for both serum and plasma within a matrix set. Aliquots were blinded and randomized for testing. Each aliquot was tested in duplicate. By testing duplicates of 3 concentrations per donor and 5 donors per matrix, there were a total of 30 results per matrix. All samples matched expected results, with all contrived positive serum and plasma samples testing positive and all negative serum and plasma samples testing negative. Therefore, positive percent agreement for plasma is 100% (20/20) and negative percent agreement is 100% (10/10) when compared to the matched comparator matrix (i.e. serum).

REFERENCES

Li, X., Geng, M., Peng, Y., Meng, L., & Lu, S. (2020). Molecular immune pathogenesis and diagnosis of COVID-19. Journal of Pharmaceutical Analysis. https://doi.org/10.1016/J.JPHA.2020.03.001

Okba, N. M. A., Muller, M. A., Li, W., Wang, C., GeurtsvanKessel, C. H., Corman, V. M., Lamers, M. M., Sikkema, R. S., de Bruin, E., Chandler, F. D., Yazdanpanah, Y., le Hingrat, Q., Descamps, D., Houhou-Fidouh, N., Reusken, C. B. E. M., Bosch, B.-J., Drosten, C., Koopmans, M. P. G., & Haagmans, B. L. (2020). SARS-CoV-2 specific antibody responses in COVID-19 patients. MedRxiv, 2020.03.18.20038059. https://doi.org/10.1101/2020.03.18.20038059

Okba, N. M. A., Muller, M. A., Li, W., Wang, C., GeurtsvanKessel, C. H., Corman, V. M., et al. (2020). Severe Acute Respiratory Syndrome Coronavirus 2−Specific Antibody Responses in Coronavirus Disease 2019 Patients. Emerging Infectious Diseases, 26(7).

Udugama, B., Kadhiresan, P., Kozlowski, H. N., Malekjahani, A., Osborne, M., Li, V. Y. C., Chen, H., Mubareka, S., Gubbay, J., & Chan, W. C. W. (2020). Diagnosing COVID-19: The Disease and Tools for Detection. ACS Nano. https://doi.org/10.1021/acsnano.0c02624

Wölf el, R., Corman, V.M., Guggemos, W., Seilmaier, M., Zange, S., Müller, M.A., et al. (2020). Virological assessment of hospitalized patients with COVID-2019. Nature. https://doi.org/10.1038/s41586-020-2196-x

Wu, F., Zhao, S., Yu, B., Chen, Y.-M., Wang, W., Song, Z.-G., Hu, Y., Tao, Z.-W., Tian, J.-H., Pei, Y.-Y., Yuan, M.-L., Zhang,

Y.-L., Dai, F.-H., Liu, Y., Wang, Q.-M., Zheng, J.-J., Xu, L., Holmes, E. C., & Zhang, Y.-Z. (2020). A new coronavirus associated with human respiratory disease in China. Nature, 579(7798), 265–269. https://doi.org/10.1038/s41586-020-2008-3

Yong, S.E.F., Anderson, D.E., Wei, W.E., Pang, J., Chia, W.N., Tan, C.W., et al. (2020). Connecting clusters of COVID-19: an epidemiological and serological investigation. The Lancet Infectious Diseases. https://doi.org/10.1016/S1473-3099(20)30273-5

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Luo, Y., Guo, H., Jiang, R.-D., Liu, M.-Q., Chen, Y., Shen, X.-R., Wang, X., … Shi, Z.-L. (2020). A pneumonia outbreak associated with a new coronavirus of probable bat origin. Nature, 579(7798), 270–273. https://doi.org/10.1038/s41586-020-2012-7

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Part Number: 900255-03
Effective Date: ##/##/2021

Catalog No. COVE-G

Note: Additional copies of this SCoV-2 Detect™ IgG ELISA Kit Package Insert can be obtained online at www.bit.ly/cove-g.
Paper copies are available upon request at inquiries@inbios.com

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COVE-G EUA/CE SCoV-2 Detect™ IgG ELISA Insert Part No. 900255-03 Effective Date: ##/##/2021 Page 18 of 18

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