The Sofia 2 SARS Antigen+ FIA is a lateral flow immunofluorescent sandwich assay that is used with the Sofia 2 instrument for the rapid, qualitative detection of SARS-CoV-2 nucleocapsid protein antigens directly in anterior nasal swab specimens from individuals with signs and symptoms of upper respiratory infection (i.e., symptomatic) when testing is started within 6 days of symptom onset. The test is intended for use as an aid in the diagnosis of SARS-CoV-2 infections (COVID-19) in symptomatic individuals when tested at least twice over three days with at least 48 hours between tests.

The test does not differentiate between SARS-CoV and SARS-CoV-2.

A negative test result is presumptive, and it is recommended these results be confirmed by a molecular SARS-CoV-2 assay. Negative results do not preclude SARS-CoV-2 infections and should not be used as the sole basis for treatment or other patient management decisions.

Positive results do not rule out co-infection with other respiratory pathogens.

Performance characteristics for SARS-CoV-2 were established during the 2021-2022 SARS-CoV-2 pandemic when SARS-CoV-2 Omicron was the predominant SARS-CoV-2 variant in circulation. When other SARS-CoV-2 virus variant are emerging, performance characteristics mav vary.

This test is intended for prescription use only and can be used in Point-of-Care settings.

Device Description

The Sofia 2 SARS Antigen+FIA is based upon a lateral flow technology that employs immunofluorescence technology in a sandwich design that is used with Sofia 2 to detect nucleocapsid protein from the SARS-CoV-2 virus in human anterior nasal swab specimens.

The patient sample is placed in the Reagent Tube, during which time the virus particles in the sample are disrupted, exposing internal viral nucleoproteins. After disruption, the sample is dispensed into the Test Cassette sample well. The Test strip is composed of the following biochemical components dried and immobilized onto the nitrocellulose membrane: 1) sample pad that receives the specimen; 2) a label pad that contains detection fluorescent micro-particles, coated with monoclonal antibodies that are specific for SARS-CoV-2 nucleocapsid antigen: 3) embedded monoclonal antibodies specific for SARS-CoV-2 nucleocapsid antigen to capture the antigen-microparticle complex at the test line location. The sample pad facilitates migration of the sample fluid across the nitrocellulose strip into the absorbent pad. The test strip also contains a desiccant that does not participate in the assay but serves as a stabilizing agent during storage.

Sample is applied to in the sample well and migrates through a test strip, then passes through the test and control lines. If SARS-CoV-2 viral antigen is present, they will be bound by the fluorescent microparticles in the label pad region, forming an antigen-microparticle complex. The test line is coated with monoclonal antibodies that are specific to SARS-CoV-2 nucleocapsid antigen and is intended to capture the antigen-microparticle complex. If SARS-CoV-2 viral antigen is not present, the fluorescent microparticles will not be trapped by the capture antibodies nor detected by Sofia 2.

The Sofia 2 SARS Antigen+FIA employs antibody-tagged microparticles dyed with a fluorescent compound, to be detected and read by the Sofia 2 reader instrument. The Sofia 2 analyzers automatically scan/image the test strip, collect and analyze the fluorescence data, and then calculate and report the result as either positive, negative, or invalid.

Additionally, the Sofia 2 Antigen+ FIA utilizes a reference line for the Sofia 2 reader (to locate the test line and negative control line) and a procedural control (to assess for sample presence and adequate sample flow). No colored lines will be visible in the test window of the fluorescent assay cassette, thereby preventing visual interpretation of the test results. The operator must use the Sofia 2 analyzer to obtain a test result.

The Sofia SARS Antigen FIA Control Swabs are intended to be used as quality control samples representative of positive and negative test samples, to demonstrate that the reagents are functional and that the assay procedure is correctly perform.

AI/ML Overview

Acceptance Criteria and Device Performance for Sofia 2 SARS Antigen+ FIA

The Sofia 2 SARS Antigen+ FIA is a qualitative lateral flow immunoassay designed for rapid detection of SARS-CoV-2 nucleocapsid protein antigens in anterior nasal swab specimens. The following details outline the acceptance criteria and the studies conducted to prove the device meets these criteria.

1. Acceptance Criteria and Reported Device Performance

Study Trait	Acceptance Criteria (Implicit from Study Design and Desired Performance)	Reported Device Performance
Precision/Repeatability (Intra-site)	- High Negative samples (0.04 x LoD) should demonstrate an expected negative agreement (e.g., >90%).- Low Positive samples (1 x LoD) should demonstrate an expected positive agreement (e.g., >95%).- Moderate Positive samples (3 x LoD) should demonstrate high expected positive agreement (e.g., >95%).- Zero invalid test results throughout the study (or very low %).	- Negative samples: 99.4% expected negative agreement (159/160)- High Negative samples (0.04 x LoD): 95.0% expected negative agreement (152/160)- Low Positive samples (1 x LoD): 98.1% expected positive agreement (157/160)- Moderate Positive samples (3 x LoD): 99.4% expected positive agreement (159/160)- 0 invalid test results (out of 640 replicates)
Reproducibility (Inter-site)	- High Negative samples (0.04 x LoD) should demonstrate reasonable negative agreement across sites and operators.- Low Positive samples (1 x LoD) should demonstrate high positive agreement across sites and operators.- Moderate Positive samples (3 x LoD) should demonstrate high positive agreement across sites and operators.- Zero invalid test results throughout the study (or very low %).	- Negative samples: 100.0% expected negative agreement (120/120)- High Negative samples (0.04 x LoD): 55.0% expected negative agreement (66/120) - Note: This is lower than typical ideal scenarios, but likely deemed acceptable given the nature of a "high negative" near the detection limit.- Low Positive samples (1 x LoD): 99.2% expected positive agreement (119/120)- Moderate Positive samples (3 x LoD): 99.2% expected positive agreement (119/120)- 0 invalid test results (out of 480 samples)
Analytical Specificity (Cross-reactivity & Interference)	- No cross-reactivity with a defined panel of common respiratory pathogens (bacteria, viruses, fungus) at specified concentrations.- No interference from common endogenous and exogenous substances found in nasal specimens at specified concentrations.- 100% negative agreement in the absence of SARS-CoV-2.- 100% positive agreement in the presence of SARS-CoV-2.	- All 28 organisms/viruses tested showed 100.0% negative agreement (5/5 replicates) for cross-reactivity and 100.0% positive agreement (5/5 replicates) for interference.- All 13 endogenous/exogenous substances tested showed 100.0% positive agreement (5/5 replicates) and 100.0% negative agreement (5/5 replicates).
Limit of Detection (LoD)	- The device should consistently detect SARS-CoV-2 at a specific low concentration (LoD) with high positivity (e.g., 95% or 100%) in confirmatory studies.- Negative clinical matrix should consistently result in negative readings.	- Confirmed LoD: 1.44 x 10^4 TCID50/mL.- At confirmed LoD: 100% positivity (20/20 replicates) across both tested lots.- NCM (Negative Clinical Matrix): 0% positivity (0/5 replicates).
High-dose Hook Effect	- No false negative results should be observed at very high concentrations of SARS-CoV-2.	- All spiked samples from 10X LoD up to a maximum virus concentration (unspecified highest concentration) were 100% positive (5/5 replicates each). No hook effect observed.
Inclusivity	- The device should detect various clinically relevant SARS-CoV-2 strains/variants (e.g., Delta, Omicron BA.1, BA.2) with high positivity.	- Heat-inactivated SARS-CoV-2 (isolate Italy-INMI1): 100.0% positivity (5/5 replicates) at 2.43E+05 TCID50/mL.- Heat-inactivated SARS-CoV-2 (Delta B.1.617.2): 100.0% positivity (5/5 replicates) at 1.00E+04 TCID50/mL.- Heat-inactivated SARS-CoV-2 (Omicron BA.1): 100.0% positivity (5/5 replicates) at 2.36E+04 TCID50/mL.- Heat-inactivated SARS-CoV-2 (Omicron BA.2): 100.0% positivity (5/5 replicates) at 8.22E+03 TCID50/mL.
Clinical Performance	- Demonstrate acceptable Positive Percent Agreement (PPA) and Negative Percent Agreement (NPA) compared to a highly sensitive RT-PCR comparator, within defined confidence intervals. The specific thresholds would be pre-defined by regulatory guidelines (e.g., FDA's EUA templates or De Novo requirements for diagnostics). While not explicitly stated as a numerical criterion, the presented results suggest approval, implying the performance met the agency's expectations for a Class II device.	- PPA (Clinical Sensitivity): 89.0% (97/109; 95% CI: 81.7% - 93.6%)- NPA (Clinical Specificity): 99.6% (470/472; 95% CI: 98.5% - 99.9%)

2. Sample Size and Data Provenance

Test Set Sample Sizes:

Precision/Repeatability: 640 replicates (160 replicates per analyte level/kit lot for 4 levels x 2 lots).
Reproducibility: 480 replicates (120 replicates per analyte level x 4 levels).
Analytical Specificity (Cross-reactivity & Interference):
- Cross-reactivity: 5 replicates per organism/virus (28 tested) = 140 replicates for negative agreement. 5 replicates per organism/virus + 2xLoD SARS-CoV-2 (25 tested, some "Not Tested" for interference) = 125 positive replicates for interference.
- Interfering Substances: 5 replicates per substance (13 tested) for both positive and negative agreement = 130 replicates.
Limit of Detection (LoD):
- Preliminary LoD: 5 replicates per dilution (6 dilutions) x 2 lots = 60 replicates.
- Confirmatory LoD: 20 replicates at preliminary LoD concentration for each of 2 lots = 40 replicates.
High-dose Hook Effect: 5 replicates per concentration (4 concentrations) = 20 replicates.
Inclusivity: 5 replicates per strain/variant (4 tested) = 20 replicates.
Clinical Study (Accuracy): 581 evaluable subjects.

Data Provenance:

Country of Origin: Not explicitly stated for analytical studies, but given the FDA review, it is implicitly expected to be a regulated environment. For the clinical study, it was a multi-center study in a "CLIA-waived" setting, which refers to US clinical laboratories.
Retrospective or Prospective:
- Analytical Performance Studies (Precision, Reproducibility, Analytical Specificity, LoD, Hook Effect, Inclusivity): These are typically prospective, lab-controlled experiments with contrived samples designed specifically for the study.
- Clinical Studies: "multi-center, prospective study conducted from August 2021 to November 2022."

3. Number of Experts and Qualifications for Ground Truth

Analytical Studies: For analytical studies (Precision, Reproducibility, LoD, Cross-reactivity, Interference, Hook Effect, Inclusivity), the ground truth is established by the known concentrations of spiked analytes (e.g., heat-inactivated SARS-CoV-2, other microbes, interfering substances). This does not involve human experts establishing ground truth beyond standard laboratory technician expertise in preparing and measuring these concentrations.
Clinical Study: The ground truth for the clinical study was established by an "highly sensitive Emergency Use Authorization (EUA) authorized RT-PCR comparator assay." This is a laboratory-based molecular test, often considered the gold standard for SARS-CoV-2 detection, and does not involve human experts in the conventional sense of image adjudication or clinical consensus. The RT-PCR results themselves serve as the ground truth.

4. Adjudication Method for the Test Set

Analytical Studies: Not applicable. Ground truth is determined by precise laboratory methods and known concentrations.
Clinical Study: Not applicable. The comparator RT-PCR assay is a definitive laboratory test; there is no mention of a human-based adjudication process for the RT-PCR results.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

No, a MRMC comparative effectiveness study was not done.
This device is an automated, instrument-read diagnostic assay (Sofia 2 SARS Antigen+ FIA). The results are generated by the instrument (Sofia 2 Analyzer) based on fluorescent signals and programmed algorithms, not by human interpretation of images or signals. Therefore, a human-in-the-loop study to assess how human readers improve with AI assistance is not relevant to this type of device. The study evaluates the standalone performance of the device compared to a reference method (RT-PCR).

6. Standalone Performance (Algorithm Only without Human-in-the-Loop)

Yes, the performance data presented for the Sofia 2 SARS Antigen+ FIA are standalone performance, i.e., algorithm only without human-in-the-loop performance.
The "Sofia 2 analyzers automatically scan/image the test strip, collect and analyze the fluorescence data, and then calculate and report the result as either positive, negative, or invalid." The operator only uses the analyzer to obtain the result; they do not visually interpret the test or make diagnostic decisions based on human observation of the test strip.

7. Type of Ground Truth Used

Analytical Studies: The ground truth was based on known concentrations of heat-inactivated SARS-CoV-2 or other microorganisms/substances in controlled laboratory settings. This is a form of "spiked sample" ground truth.
Clinical Study: The ground truth was established using an "highly sensitive Emergency Use Authorization (EUA) authorized RT-PCR comparator assay." This is a laboratory-based molecular diagnostic method, considered the gold standard for detecting SARS-CoV-2 RNA.

8. Sample Size for the Training Set

No information is provided about a specific "training set" related to an AI/algorithm development in the context of machine learning. The algorithms referenced ("method-specific algorithms," "software specific cutoff," "specific algorithms") for the Sofia 2 analyzer relate to processing fluorescent signals and determining thresholds for positive/negative results, which are typically derived from extensive analytical characterization and optimization using laboratory-controlled samples, rather than a distinct "training set" in the machine learning sense often seen with image-based AI. The document implies these algorithms are developed and refined through the analytical performance studies (such as LoD, linearity, etc.) using various known concentrations.

9. How the Ground Truth for the Training Set Was Established

As mentioned above, a traditional "training set" as understood in a machine learning context is not explicitly described. The "ground truth" for establishing the device's operational algorithms and cut-offs would have been determined through laboratory experiments with precisely known concentrations of analytes. This process involves:
- Identifying the Limit of Detection (LoD).
- Evaluating signal response across a range of concentrations.
- Using reference lots and known values during development to establish parameters for calculations and cut-offs.
- "Final cut-off values were further validated as part of the analytical and clinical studies." This suggests an iterative process of development, testing, and validation against a known ground truth (spiked samples for analytical studies, RT-PCR for clinical).

Summary

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EVALUATION OF AUTOMATIC CLASS III DESIGNATION FOR Sofia 2 SARS Antigen+ FIA, Sofia 2 SARS Antigen+ FIA Control Swab Set DECISION SUMMARY

I Background Information:
A De Novo Number DEN220039
B Applicant Quidel Corporation
C Proprietary and Established Names Sofia 2 SARS Antigen+ FIA, Sofia 2 SARS Antigen+ FIA Control Swab Set

D Regulatory Information

ProductCode(s)	Classification	RegulationSection	Panel
QVF	Class II	21 CFR 866.3982 - Simplequalitative device todirectly detect SARS-CoV-2 virus targets inhuman clinical specimensfor settings operatingunder a certificate ofwaiver or at home use	MI - Microbiology

Submission/Device Overview: II

A Purpose for Submission:

De Novo request for evaluation of automatic class II designation for the Sofia 2 SARS Antigen + FIA, Sofia 2 SARS Antigen+ FIA Control Swab Set

B Measurand:

Nucleocapsid protein antigen from SARS-Coronavirus 2 (SARS-CoV-2)

C Type of Test:

Qualitative lateral flow immunoassay

Food and Drug Administration 10903 New Hampshire Avenue Silver Spring, MD 20993-0002 www.fda.qov

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III Indications for Use:

A Intended Use(s):

See Indications for Use below.

B Indication(s) for Use:

The test does not differentiate between SARS-CoV and SARS-CoV-2.

Positive results do not rule out co-infection with other respiratory pathogens.

This test is intended for prescription use only and can be used in Point-of-Care settings.

C Special Conditions for Use Statement(s): Rx - For Prescription Use Only

D Special Instrument Requirements: Sofia 2 Analyzer

IV Device/System Characteristics:

A Device Description:

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the sample fluid across the nitrocellulose strip into the absorbent pad (See Figure 1 below). The test strip also contains a desiccant that does not participate in the assay but serves as a stabilizing agent during storage.

Image /page/2/Figure/1 description: This image shows a diagram of a lateral flow assay test strip. The diagram labels the different parts of the test strip, including the sample pad, label pad, control line, test line, reference line, procedural control zone, and absorbent pad. An arrow indicates the direction of sample flow through the test strip.

Figure 1: Schematic of the Sofia 2 Antigen + FIA Test Strip

B Principle of Operation

The Sofia 2 SARS Antigen+ FIA employs immunofluorescence based lateral flow technology in a sandwich design to detect nucleocapsid protein from SARS-CoV-2. Following sample collection, the patient's anterior nasal swab sample is placed in the reagent tube, to lyse the sample and solubilize viral nucleoproteins of the analyte. After lysis, the sample is loaded onto the test cassette sample well. The sample migrates across the test strip first and then flows across 3 distinct areas: 1) the test line, 2) the procedural control line, and 3) the reference line. If SARS-CoV-2 viral antigens are present, they will be captured by antibodies and the fluorescence-tagged complex will be bound to the test line on the test strip.

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The test cassette is placed inside of the Sofia 2 instrument for timed test reaction and signal development (WALK AWAY Mode). Thereafter, the Sofia 2 will automatically scan the test strip, expose the strip to UV light, and measure the fluorescent signal by processing the results using method-specific algorithms. A positive result for the analyte is determined by detection of fluorescent signals at the Test Line that are above a software specific cutoff. If SARS-CoV-2 viral antigens are not present, no fluorescent complexes are formed at the Test Line and no signal is detected by Sofia 2. In the absence of SARS-CoV-2 a signal is formed only at the Control Line. If the Control Line is not detected by the Sofia 2 the sample result is invalid. Test results are displayed on the screen as Positive. Negative, or Invalid.

C Instrument Description Information

1. Instrument Name: Sofia 2
1. Specimen Identification: SARS-CoV-2 nucleocapsid protein antigen
1. Specimen Sampling and Handling: Direct anterior nasal swab specimens
1. Calibration:

Sofia 2 reminds the user to check the calibration status of the instrument every thirty days. utilizing a specially labeled Calibration Cassette. This cassette uses a fluorescent reagent embedded in plastic along with a unique barcode that prevents the analyzer from mistaking the Calibration Cassette for a standard assay cassette. If calibration is needed, the Sofia 2 analyzer will calibrate automatically after the cassette is inserted into the instrument. If the calibration has expired, the Sofia 2 analyzer will not allow tests to be run.

1. Quality Control:
  Quality Control is facilitated by scanning the lot-specific QC card that is provided on the unit carton of each kit. The QC card "informs" the Sofia 2 analyzer as to which test is being subjected to quality control evaluation, and provides the kit's lot number, test cassette's lot number, and the kit's expiration date. Following scanning of the QC card, the user is prompted to insert a cassette containing the extracted Positive Control test sample, followed by the extracted Negative Control test sample.

V Standards/Guidance Documents Referenced:

DocumentNumber	Title	PublishingOrganization	Applicable Stud
EN 13612:2002/AC:2002	Performance evaluation of in vitro diagnosticmedical devices	EuropeanStandard	All
EP05-A3	Evaluation of Precision of QuantitativeMeasurement Procedures; ApprovedGuideline—Third Edition (Chapter 1	CLSI	Precision/RepeatabilityandReproducibility
	Introduction and 3 Single-Site PrecisionEvaluation Study)
EP12-A2	User Protocol for Evaluation of Qualitative TestPerformance; Approved Guideline-SecondEdition (Sections 7.1 Controls, Section 8 Biasand Imprecision Studies (with focus on 8.3),and Appendix: Statistical Reasoning forPrecision Experiment Conclusions)	CLSI	Precision/RepeatabilityandReproducibility
N/A	U.S. FDA's SARS-CoV-2 Emergency UseAuthorization Antigen Template for TestDevelopers (dated 26 Oct 2020)	FDA	All
N/A	Guidance for Industry and FDA Staff,Establishing the Performance Characteristics ofIn Vitro Diagnostic Devices for the Detection orDetection and Differentiation of InfluenzaViruses (15 Jul 2011; Section 9.A.i)	FDA	Limit of Detection
N/A	Recommendations for Clinical LaboratoryImprovement Amendments of 1988 (CLIA)Waiver Applications for Manufacturers of InVitro Diagnostic Devices; Guidance forIndustry and Food and Drug AdministrationStaff (dated 26 Feb 2020; Section IV.A. Tier1:Risk Analysis and Flex Studies)	FDA	Cross-reactivityand MicrobialInterference:DevelopmentRead Time andTest ResultStability
EN ISO14971:2019	Application of Risk Management to MedicalDevices	ISO	Risk Analysis
EN ISO13485:2016	Medical devices - Quality management systems- Requirements for regulatory purposes	ISO	SoftwareValidation
IEC 60601-1-2:2014	Medical electrical equipment - Part 1-2: Generalrequirements for basic safety and essentialperformance Collateral standard:Electromagnetic Disturbances Requirementsand tests.	IEC	ElectromagneticCompatibility andElectrical Safety
CISPR 11Edition6.0:2015	Industrial, scientific and medical equipmentRadio-frequency disturbance characteristicsLimits and methods of measurement.	CISPR	ElectromagneticCompatibility andElectrical Safety
EN 61326-1:2013 / EN61326-2-6:2012	Electrical equipment for measurement, controland laboratory use - EMC requirements - Part1: General requirements. (Appendix 17-2)	IEC	ElectromagneticCompatibility andElectrical Safety
IEC 61010-1:2010 (thirdedition)	Safety requirements for electrical equipment formeasurement, control, and laboratory use - Part1: General requirements. (Appendix 17-6)	IEC	ElectromagneticCompatibility andElectrical Safety
IEC62133:2012	Secondary cells and batteries containingalkaline or other non-acid electrolytes - Safetyrequirements for portable sealed secondarycells, and for batteries made from them, for usein portable applications. (Appendix 17-7)	IEC	ElectromagneticCompatibility andElectrical Safety

Table 1. Referenced Standards and Guidance Documents

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Performance Characteristics: VI

A Analytical Performance:

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1. Precision/Reproducibility:

a) Precision and Repeatability

The precision/repeatability (P/R) studies herein evaluated four (4) levels of UVinactivated SARS-CoV-2 in Negative Clinical Matrix (NCM): Negative (C0), High Negative (C5), Low Positive (C95), and Positive (3X LoD) - in two (2) events ('runs') per day, two (2) replicates per event, over a minimum of twenty (20) days on each of two Sofia 2 SARS Antigen+ FIA devices/reagent lots (see table below). The precision testing was conducted according to the Package Insert using two operators.

Precision and Reproducibility Study Conditions
Parameter	Per Lot	Overall
Analyte Levels	4	4
Days	20	20
Events ('runs')	2 runs per day	40
Replicates	2 per run	160 per level
Operators	1 per level	at least 2
Overall	80 replicates per level.320 data points	640 data points

			Table 2. Precision and Repeatability Study Design and Test Parameters

						Table 3. Precision and Repeatability Study - Test Sample Panel
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Spiking Concentrations
Level	Concentration(TCID50/mL)
Negative Sample (C₀)	N/A
High Negative (C₅)	0.04 x LoD
Low Positive (C₉₅)	1 x LoD
Moderate Positive	3 x LoD

Qualitative results, Quantitative results, and Variance Component Analysis are summarized here:

Out of 640 replicates tested, there were zero (0) invalid test results obtained. .
The negative samples produced an overall 99.4% expected negative agreement . (159/160)
The high negative samples produced 95.0% expected negative agreement (152/160). .
The low positive samples produced 98.1% expected positive agreement (157/160). .
The moderate positives sample produced 99.4% expected positive agreement . (159/160).

Kit Lot	Negative	High Negative		Low Positive		Moderate Positive
	1	1	2	1	2	1	2
Run 1	40/40	39/40	40/40	40/40	40/40	40/40	40/40
Run 2	40/40	35/40	38/40	40/40	37/40	40/40	39/40
Total	80/80	74/80	78/80	80/80	77/80	80/80	79/80

Table 4. Precision and Repeatability Study - Summary Results

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%Agreement	100.0%	98.75%	92.5%	97.5%	100.0%	96.25%	100.0%	98.75%
(95% CI)	[95.4% -100.0%]	[93.3% -99.8%]	[84.6% -96.5%]	[91.3% -99.3%]	[95.4% -100.0%]	[89.5% -98.7%]	[95.4% -100.0%]	[93.3% -99.8%]
%Agreement	99.4%		95.0%		98.1%		99.4%
95% CI)	[96.5% - 99.9%]		[90.4% - 97.4%]		[94.6% - 99.4%]		[96.5% - 99.9%]

b) Reproducibility

The study was designed to evaluate site-to-site, operator-to-operator, and level-to-level variability and demonstrate that the Sofia 2 SARS Antigen+ FIA can be performed consistently and correctly. This study was conducted at 1000 distinct sites, each with two (2) different operators, testing two (2) test lots, using a coded panel of contrived samples (refer to Table 3 above). Four analyte levels were each tested as follows: 2 operators x 3 sites x 5 days x 2 device lots x 2 replicates = 120 replicates for each of the different analyte levels to a total of 480 replicates per site.

Out of 480 samples tested. there were zero (0) invalid test results obtained. .
The negative samples produced an overall 100.0% expected negative agreement . (120/120)
The high negative samples produced 55.0% expected negative agreement (66/120). .
The low positive samples produced 99.2% expected positive agreement (119/120). .
The moderate positive samples produced 99.2% expected positive agreement . (119/120).

Site	Negative	0.04x LoD	1x LoD	3x LoD
1	40/40	26/40	40/40	39/40
2	40/40	11/40	40/40	40/40
3	40/40	29/40	39/40	40/40
Total	120/120	66/120	119/120	119/120
%Agreement(95% CI)	100%	55%	99.2%	99.2%
	[96.9% - 100.0%]	[46.1% - 63.6%]	[95.4% - 99.9%]	[95.4% - 99.9%]

Table 5. Reproducibility Study - Summary Results

2. Linearity:

This study is not applicable as this test device is a qualitive assay.

3. Analytical Specificity/Interference:

a) Cross-reactivity and Microbial Interference Study

The cross-reactivity and potential interference were evaluated by testing various bacteria (7), viruses (19), fungus (1), and negative matrixes (2) with the Sofia 2 SARS Antigen+ FIA. Each organism and virus were tested in five (5) replicates in the absence or presence of 2xLoD of heat-inactivated SARS-CoV-2 (isolate USA-WA1/2020). None of the

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organisms and viruses evaluated demonstrated cross-reactivity and interference in the assay at the concentrations tested.

Virus/Microorganism	Strain	Conc.	Cross-Reactivity(NegativeAgreement)(SCV-2negativereplicates/allreplicates)	Interference(PositiveAgreement)(SCV-2positivereplicates/allreplicates)
Adenovirus CultureFluid	Type 1 (SpeciesC)	2.04E+05TCID50/mL	100.0%(5/5)	100.0%(5/5)
Coronavirus CultureFluid(Heat Inactivated)	229E	1.26E+05TCID50/mL	100.0%(5/5)	100.0%(5/5)
Coronavirus CultureFluid(Heat Inactivated)	OC43	1.00E+05TCID50/mL	100.0%(5/5)	100.0%(5/5)
Coronavirus CultureFluid(Heat Inactivated)	NL63	3.40E+04TCID50/mL	100.0%(5/5)	100.0%(5/5)
Enterovirus Type 68Major GroupCulture Fluid	2014 Isolate 1	2.29E+05TCID50/mL	100.0%(5/5)	100.0%(5/5)
HumanMetapneumovirus 9	A1	1.27E+05TCID50/mL	100.0%(5/5)	100.0%(5/5)
Human RhinovirusType 1A	N/A	1.78E+05TCID50/mL	100.0%(5/5)	100.0%(5/5)
Influenza A	A/Brisbane/10/07	1.00E+05TCID50/mL	100.0%(5/5)	100.0%(5/5)
Influenza A H1N1	NewCaledonia/20/99	1.78E+05TCID50/mL	100.0%(5/5)	100.0%(5/5)
Influenza A	NewCaledonia/20/99Custom formalininactivated	4.02E+05TCID50/mL	Not Tested	100.0%(5/5)
Influenza A	Brisbane/02/18	5.62E+03TCID50/mL	Not Tested	100.0%(5/5)
Influenza A	California/07/09	4.17E+04TCID50/mL	Not Tested	100.0%(5/5)
Influenza B VirusCulture Fluid	Brisbane/33/08	2.34E+04TCID50/mL	100.0%(5/5)	100.0%(5/5)
MERS-CoV(Heat Inactivated)	Florida/USA-2_SaudiArabia_2014	1.04E+05TCID50/mL	100.0%(5/5)	100.0%(5/5)
Virus/Microorganism	Strain	Conc.	Cross-Reactivity(NegativeAgreement)(SCV-2negativereplicates/allreplicates)	Interference(PositiveAgreement)(SCV-2positivereplicates/allreplicates)
Parainfluenza Type 1Culture Fluid	N/A	1.00E+05TCID50/mL	100.0%(5/5)	100.0%(5/5)
Parainfluenza Type 2Culture Fluid	N/A	9.97E+05TCID50/mL	100.0%(5/5)	100.0%(5/5)
Parainfluenza Type 3Culture Fluid	N/A	2.29E+05TCID50/mL	100.0%(5/5)	100.0%(5/5)
Parainfluenza Type 4BCulture Fluid	N/A	1.00E+05TCID50/mL	100.0%(5/5)	100.0%(5/5)
Respiratory SyncytialVirus	Type A	1.51E+05TCID50/mL	100.0%(5/5)	100.0%(5/5)
Bordetella pertussis,ATCC 18323(NCTC 10739)	Type b; Eagan	3.05E+07CFU/mL	100.0%(5/5)	100.0%(5/5)
Chlamydophilapneumoniae	Z500[IOL207]	1.06E+07IFU/mL	100.0%(5/5)	100.0%(5/5)
Haemophilusinfluenzae	Type B, NCTC8468	2.60E+07CFU/mL	100.0%(5/5)	100.0%(5/5)
Legionellapneumophila	ATCC 33152(Philadelphia-1)	2.00E+07CFU/mL	100.0%(5/5)	100.0%(5/5)
Pneumocystisjirovecii-S. cerevisiaeRecombinant	W303-Pji	5.29E+05CFU/mL	100.0%(5/5)	100.0%(5/5)
Mycoplasmapneumoniae	M129	1.35E+07CCU/mL	100.0%(5/5)	100.0%(5/5)
Streptococcuspneumoniae, Type 19F	ATCC 49619(262 [CIP104340])	1.90E+07CFU/mL	100.0%(5/5)	100.0%(5/5)
Streptococcuspyogenes	ATCC 19615(Bruno [CIP104226])	1.60E+07CFU/mL	100.0%(5/5)	100.0%(5/5)
S. aureus MRSA	N/A	1.03E+06CFU/mL	100.0%(5/5)	100.0%(5/5)
S. aureus MSSA	N/A	1.15E+06CFU/mL	100.0%(5/5)	100.0%(5/5)
S. epidermidis	N/A	1.29E+06CFU/mL	100.0%(5/5)	100.0%(5/5)
Negative Nasal Matrix(normal flora)	UTM	N/A	100.0%(5/5)	100.0%(5/5)
Virus/Microorganism	Strain	Conc.	Cross-Reactivity(NegativeAgreement)(SCV-2negativereplicates/allreplicates)	Interference(PositiveAgreement)(SCV-2positivereplicates/allreplicates)
Negative Nasal Matrix(normal flora)	CDC ViralTransport	N/A	100.0%(5/5)	100.0%(5/5)

Table 6. Cross-Reactivity and Microbial Interference Study - Summary Results

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b) Endogenous and Exogenous Interfering Substances Study

This study evaluated endogenous or exogenous substances that may potentially interfere with the Sofia 2 SARS Antigen+ FIA. Each potentially interfering substance (see table below) was tested in negative clinical matrix (NCM) at the targeted initial concentrations in the absence (negative) and presence (positive) of heat-inactivated SARS-CoV-2 (isolate USA-WA1/2020) at the 2X LoD level. The effects of the substances were evaluated by the agreement with the expected negative or positive results. Five (5) replicates were tested for each sample prepared.

Substance	Active Ingredient ofSubstance	InterferentConc.	PositiveAgreement(SCV-2 positivereplicates/allreplicates)	NegativeAgreement(SCV-2 negativereplicates/allreplicates)
Afrin-nasalspray	Oxymetazoline	5% v/v	100.0%(5/5)	100.0%(5/5)
Blood (human)	Blood	5% v/v	100.0%(5/5)	100.0%(5/5)
Chloraseptic,Cepacol	Benzocaine, Menthol	0.7 g/mL	100.0%(5/5)	100.0%(5/5)
Flonase	Fluticasone	5% v/v	100.0%(5/5)	100.0%(5/5)
Halls ReliefCherry Flavor	Menthol	0.8 g/mL	100.0%(5/5)	100.0%(5/5)
NasocortAllergy 24 Hour	Triamcinolone	5% v/v	100.0%(5/5)	100.0%(5/5)
Neo-Synephrine	Phenylephrinehydrochloride	5% v/v	100.0%(5/5)	100.0%(5/5)
Oseltamivir	Oseltamivir	2.2 μg/mL	100.0%(5/5)	100.0%(5/5)
Purified mucinprotein	Mucin protein	2.5 mg/mL	100.0%(5/5)	100.0%(5/5)
Rhinocort	Budesonide(Glucocorticoid)	5% v/v	100.0%(5/5)	100.0%(5/5)
Saline nasalspray	Saline	15% v/v	100.0%(5/5)	100.0%(5/5)

Table 7. Interfering Substances Study - Summary Results

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Substance	Active Ingredient ofSubstance	InterferentConc.	PositiveAgreement(SCV-2 positivereplicates/allreplicates)	NegativeAgreement(SCV-2 negativereplicates/allreplicates)
Tobramycin	Tobramycin	1.25mg/mL	100.0%(5/5)	100.0%(5/5)
Zanamivir	Zanamivir	282 ng/mL	100.0%(5/5)	100.0%(5/5)
Zicam coldremedy	Galphimia glauca,Luffa operculata,Sabadilla	5% v/v	100.0%(5/5)	100.0%(5/5)

4. Assay Reportable Range:

This section is not applicable as this test device is a qualitative assay.

1. Traceability, Stability and Expected Values (Controls, Calibrators, or Methods):

a) Internal Controls

The test strip has several built-in control features to ensure that each test is performed. properly. These include the: 1) Control Line, 2) Reference Line and 3) the Procedural Control Zone.

The Control Line is the first line that the extracted specimen encounters as it begins . its migration across the length of the nitrocellulose test strip. The Control Line is comprised of mouse immunoglobulin (Ig). The Control Line acts as a filter to prevent non-specific binding downstream in the test line and reference line formation areas of the test strip.
. The Reference Line is used by the instrument to determine the orientation of the test strip and the locations of Test Line and Procedural Control Zone on the test strip. The Reference Line is the last line that the extracted specimen encounters before it enters the absorbent pad at the end of the test strip. The analyzer images the strip and uses specific algorithms to validate the peaks and locate the exact position of the Reference Line within the range. The reagents must flow through the test strip and the fluorescent signals at the Reference Line location must meet the specifications by the fluorescent response, width, orientation and location for a valid Reference Line peak. If there is no valid Reference Line peak, the analyzer will report the result as "invalid". After the Reference Line peak is found, the software calculates the location of the Test Line and Procedural Control zone fixed distances from the Reference Line.
. The Procedural Control Zone (PCZ) is used by the Sofia 2 analyzer to assess for adequate sample flow and sample volume. This PCZ of the nitrocellulose test strip is located between the Absorbent Pad and the Reference Control Line. As the assay is run, the fluid carries the europium-dyed microparticles through the test strip. For a valid assay the reagents must flow to the end of the test strip and produce a minimum fluorescent signal in the PCZ. If the fluorescent signal obtained in the zone is below the specification, the analyzer will report the result as "invalid".

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b) External Controls

Ten (10) control swabs were tested per cassette lot - control lot combination and a minimum of ten (10) Sofia 2 Analyzers were used All testing was conducted in the "Read Now" mode following the package insert instructions. For each control lot - cassette lot combination, the percent agreement to expected result was calculated as follows:

% Agreement to Expected Positive Result = 100 X [# Positive / (# Negative + # . Positive)]
· % Agreement to Expected Negative Result = 100 X [# Negative / (# Negative + # Positive)]

For each control lot - cassette lot combination, all the positive and all the negative controls produced 100% agreement with the expected results.

SARS External Controls Performance
Control	ControlLot#	CassetteLot#	n	# ofinvalid	# ofNeg	# ofPos	% ExpectedAgreement
Control Swab,Neg, SARSAntigen, Pouched	146067	210144	10	0	10	0	100
	146067	210325	10	0	10	0	100
	147223	210144	10	0	10	0	100
	147223	210325	10	0	10	0	100
Control Swab,Pos, SARSAntigen, Pouched	146072	210144	10	0	0	10	100
	146072	210325	10	0	0	10	100
	147227	210144	10	0	0	10	100
	147227	210325	10	0	0	10	100
	147367	210144	10	0	0	10	100
	147367	210325	10	0	0	10	100

Table 8. Validation of External Control Materials - Summary Results

For three positive and two negative control lots tested across two test cassette lots, the positive and negative controls produced 100% agreement with the expected results.

c) Specimen Stability

Two (2) test samples were prepared for testing in the specimen stability study: a negative sample (NCM with no analyte) and a low positive sample (NCM spiked with heat inactive SARS-CoV-2 (isolate USA-WA1/2020) at 2x LoD. A total of negative swabs and | | | | | | | | positive swabs were prepared by submerged/dipping a foam nasal swab into a liquid test sample for a minimum of five (5) minutes prior to placing into a dry transport tube. The tubes were then stored at 15°C±2°C, 30°C±2°C, in the cold room (2-8°C), or in the freezer (-20°C) for the duration of the study and were tested at the time points indicated in the table below:

	Table 9. Specimen Stability Study Design and Test Parameters
--	--------------------------------------------------------------	--

Specimen Storage Temperature/Time
Specimen StorageTemperature	Specimen Storage Time
Ambient Temperature (23.7°C)	0 hrs.	N/A	N/A	N/A	N/A
Room Temperature (15±2°C)	2 hrs.	6 hrs.	12 hrs.	24 hrs.	N/A

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Room Temperature $(30\pm2^{\circ}C)$	2 hrs.	6 hrs.	12 hrs.	24 hrs.	N/A
Refrigerated $(2-8^{\circ}C)$	6 hrs.	12 hrs.	24 hrs.	48 hrs.	72 hrs.
Frozen $(-20^{\circ}C)$	24 hrs.	48 hrs.	72 hrs.	96 hrs.	120 hrs.

A minimum of ten (10) Sofia 2 Analyzers were used. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | positive swabs were tested at each time point and storage temperature. Swab samples were processed using the Swab Test Procedure according to the Package Insert. All samples were tested on the Sofia 2 SARS Antigen+ FIA using the "Read Now" mode.

At time 0 hours, all the negative and positive test swabs produced 100% agreement with the expected results. No false positives occurred with the negative samples at any of the timepoints tested for any of the temperature conditions evaluated. Across the timepoints and temperature conditions evaluated, positive samples were positive, except for some individual replicates at 30℃ storage and one at refrigerated storage.

SpecimenStorageParameters	0 hrs.	2 hrs.	6 hrs.	12 hrs.	24 hrs.	48 hrs.	72 hrs.	96 hrs.	120hrs.
ControlAmbientTemp.(23.7°C)	100.0%(15/15)
RoomTemp.(15 $\pm$ 2°C)		100.0%(15/15)	100.0%(15/15)	100.0%(15/15)	100.0%(15/15)
RoomTemp.(30 $\pm$ 2°C)		93.3%(14/15)	100.0%(15/15)	100.0%(15/15)	86.7%(13/15)
Refrigerated(2-8°C)			100.0%(15/15)	100.0%(15/15)	100.0%(15/15)	93.3%(14/15)	100.0%(15/15)
Frozen(-20°C)					100.0%(15/15)	100.0%(15/15)	100.0%(15/15)	100.0%(15/15)	100.0%(15/15)

Table 10. Specimen Stability Study - Positive Agreement Summary Results

Based upon this study design and the results thereof, the specimen stability data support, storage of nasal swab samples at: 2-8℃ for up to 24 hours, 15℃ to 30℃ for up to 12 hours, - 20℃ or below for up to 4 days (96 hours) including two freeze-thaw cycles.

6. Detection Limit:

The Limit of Detection (LoD) of the Sofia 2 SARS Antigen+ FIA was determined by evaluating different dilutions of heat-inactivated SARS-CoV-2 (isolate USA-WA1/2020) in negative clinical matrix. The SARS-CoV-2 USA-WA1/2020 stock was diluted into negative clinical matrix (NCM) in order to target the LoD level. The negative clinical matrix was pooled human nasal swab samples eluted into saline. Six serial dilutions were made from SARS-CoV-2 USA-WA1/2020 stock into a negative clinical matrix. Five (5) replicates were tested for each of the six dilutions to determine the preliminary LoD concentration on two lots of the Sofia 2 SARS Antigen+ FIA cassettes. Thereafter, the LoD was confirmed by

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testing 20 replicates at the preliminary LoD concentration. The Sofia 2 SARS Antigen+ FIA LOD was confirmed to be 1.44 x104 TCID50/mL.

Table 11. Limit of Detection Study - Summary Results	Range Finding				Confirmation
Conc.(TCID50/mL)	n	Inv	Neg	Pos(% Pos)	n	Inv	Neg	Pos(% Pos)
				(b)(4)
2.88E+04	5	0	0	5(100%)
1.44E+04	5	0	0	5(100%)	20	0	0	20(100%)
				(b)(4)
NCM (NegativeClinical Matrix)	5	0	5	0(0.0%)
				(b)(4)
2.88E+04	5	0	0	5(100%)
1.44E+04	5	0	1	4(80.0%)	20	0	0	20(100%)
NCM (NegativeClinical Matrix)	5	0	5	0(0.0%)

Table 11. Limit of Detection Study - Summary Results

7. High-dose Hook Effect Study

A High Dose Hook Effect study was conducted to determine if a hook effect would be observed at high concentrations of the analyte (i.e., a false negative at high concentrations of SARS-CoV-2). A series of four concentrations were prepared in NCM and tested in five (5) replicates on the Sofia 2 SARS Antigen+ FIA, between and including | 000) LoD (the maximum virus concentration possible) and me LoD (high positive). The starting virus stock was was bk4) was (isolate USA-WA1/2020). All spiked samples were 100% positive, as expected, at all tested concentrations. The Sofia 2 SARS Antigen+ FIA did not display a Hook Effect for high concentrations of SARS-CoV-2 tested herein.

Table 12. High-dose Hook Effect Study - Summary Results

Sample Level	Concentration (TCID50/mL)	%Expected Agreement
(b)(4) LoD	2.30E+06	100.0% (5/5)

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40X LoD	(b)(4)	100.0% (5/5)
20X LoD		100.0% (5/5)
10X LoD		100.0% (5/5)

8. Inclusivity

This study was performed to demonstrate that the Sofia 2 SARS Antigen+ FIA assay can detect the viral strain/isolate SARS-CoV-2 (isolate Italy-INMI1). The heat-inactivated SARS-CoV-2 (isolate Italy-INMI1) stock ( different concentrations. Each concentration was tested with Treplicates until two consecutive dilutions produced 1 or more negative replicates out of 0

Strain / Isolate /Variant(Lineage)	Concentration(TCID50/mL)	n	# ofInv	# ofNeg	# ofPos	%Positivity	# of Valid ResultsMean ± SD (%CV)of S/CO
Heat InactivatedSARS-CoV-2:Isolate Italy(INMI1)	2.43E+05	5	0	0	5	100.0	52.2±0.66 (30.5%)
(b)(4)
Heat InactivatedSARS-CoV-2:Delta(B.1.617.2)	1.00E+04	5	0	0	5	100.0	52.1±0.48 (22.5%)
(b)(4)
Heat InactivatedSARS-CoV-2:Omicron BA.1(BA.1.18)	2.36E+04	5	0	0	5	100.0	51.9±0.70 (37.7%)
(b)(4)
Heat InactivatedSARS-CoV-2:Omicron BA.2(B.1.1.529)				(b)(4)
	$8.22E+03$	5	0	0	5	100.0

Table 13. Inclusivity Study - Summary Results

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9. Assay Cut-Off:

The Sofia 2 analyzer workflow calculates the cutoff values (COs) and the signal over CO ratio value (S/CO) prior to reporting the result. Values from reference lots during development were used to establish the reference values used in these calculation algorithms. Sofia 2 determines a positive or negative result based on predetermined, specific fluorescence based cutoff values, programmed into the software and established on a lot-tolot basis. Final cut-off values were further validated as part of the analytical and clinical studies.

10. Accuracy (Instrument):

Please refer to Section VI.C (Clinical Studies) for the clinical evaluation study and data that establish clinical performance and accuracy of the test device.

11. Carry-Over:

Carry-over contamination is not applicable to this test device as each sample uses an independent, new, single-use test cassette that is discarded after each run. No fluidic handling occurs in the instrument therefore the risk of carry-over was determined to be low.

B Comparison Studies:

1. Method Comparison:

Please refer to Section VI.C (Clinical Studies) below for the clinical validation, regarding the method comparison studies.

2. Matrix Comparison:

The Sofia 2 SARS Antigen+ FIA is only intended for the qualitative detection of the nucleocapsid protein antigen from SARS-CoV-2 in direct anterior nasal swab specimens. As no other specimen or sample type is claimed herein, a Matrix Comparison study is not applicable to this test device.

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C Clinical Studies:

The performance of the Sofia 2 SARS Antigen+ FIA in detecting SARS-CoV-2 viral nucleoprotein antigen was evaluated in a multi-center, prospective study conducted from August 2021 to November 2022, using 12 operators who conducted enrollment and testing of the subjects. An additional 7 operators conducted enrollment and/or sample shipments only. The study only enrolled subjects with symptoms of respiratory infection consistent with a SARS-CoV-2 infection. A total of five hundred thirty (581) subjects were consecutively enrolled and tested across six different CLIA-waived sites.

Two nasal swabs were collected from each study subject during the same visit in a randomized manner. One swab was tested on the Sofia 2 SARS Antigen+FIA by a CLIA-waived test operator at the site. The second swab was collected for testing with the comparator test, placed into a transport tube containing 3mL of Quidel Transport Medium (OTM), pre-labeled with the subject ID, refrigerated (2-8°C) in the biohazard bag within one hour from the collection, and shipped to the reference laboratory on ice packs on the same day. If same-day shipping was not possible, the swabs used for the comparator method were kept refrigerated (2-8°C) until shipment to the reference laboratory. Upon receipt by the reference laboratory, the second nasal swab was tested with a highly sensitive Emergency Use Authorization (EUA) authorized RT-PCR comparator assay, within six days of receipt. Demographics, symptoms, and health history were also collected from each subject.

There were 581 evaluable subjects with 37.5% (218/581) male and 62.5% (363/581) female, with a mean age of 41.6 years; one subject was excluded. Results obtained with the Quidel Sofia 2 SARS Antigen+ FIA test were compared to the results obtained with the RT-PCR comparator test to determine clinical sensitivity and specificity. The study cohort included 36.7% low positive samples.

The Sofia 2 SARS Antigen+ FIA demonstrated a clinical sensitivity of 89.0% (97/109; 95% CI: 81.7% - 93.6%) and a specificity of 99.6% (470/472: 95% CI: 98.5% - 99.9%) versus the comparator.

	EUA authorized RT-PCRComparator
	Pos	Neg	Total
Sofia Pos	97	2	99
Sofia Neg	12	470	482
Total	109	472	581

	Table 14. Clinical Performance of the Sofia 2 SARS Antigen+ FIA Compared to an EUA
	authorized highly sensitive RT-PCR comparator

Positive Percent Agreement (PPA) = 89.0% (97/109; 95% CI: 81.7% - 93.6%) .

Negative Percent Agreement (NPA) = 99.6% (470/472; 95% CI: 98.5% 99.9%) .
Positivity in Study Cohort = 18.761% (109/581; 95% CI: 15.8% 22.1%) .

1. Clinical Sensitivity:

Please refer to Section VI.C (Clinical Studies) above for the clinical validation. The PPA for the test is 89.0% (97/109; 95% CI: 81.7% - 93.6%).

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2. Clinical Specificity:

Please refer to Section VI.C (Clinical Studies) above for the clinical validation. The NPA for the test is 99.6% (470/472; 95% CI: 98.5% - 99.9%).

3. Serial Testing:

As a mitigation for low performance of the device at Day 0 of symptom onset, as indicated by these clinical study data and in other studies for test devices of a similar principle and design, the Intended Use for this test device (and associated Instructions for Use) include recommendations for repeat testing (i.e., test at least twice over three days with at least 48 hours between tests.). This mitigation is supported by data generated by the National Institutes for Health (NIH) and the University of Massachusetts Chan Medical School (in collaboration with the FDA) demonstrating that repeat testing over multiple days improves test performance and increases the likelihood that a COVID-19 antigen test will accurately detect an infection. These results have informed the FDA's general understanding that repeat testing after a negative result from a COVID-19 antigen test reduces the risk of a false negative result. Please refer to the following studies for additional details:

Finding a Needle in the Haystack; Design and Implementation of a Digital Site-less . Clinical Study of Serial Rapid Antigen Testing to Identify Asymptomatic SARS-CoV-2 Infection - https://www.medrxiv.org/content/10.1101/2022.08.04.22278274v1.
Performance of Screening for SARS-CoV-2 using Rapid Antigen Tests to Detect . Incidence of Symptomatic and Asymptomatic SARS-CoV-2 Infection; findings from the Test Us at Home prospective cohort study https://www.medrxiv.org/content/10.1101/2022.08.05.22278466v1

D Clinical Cut-Off:

There is no clinical cutoff related to the presence of SARS-CoV-2 in patient samples. This section is therefore not applicable.

E I Expected Values/Reference Range:

A patient sample is expected to be negative for SARS-CoV-2. This section is therefore not applicable.

Other Supportive Performance Characteristics Data: F
This section is not applicable.

VII Proposed Labeling:

The labeling supports the decision to grant the De Novo request for this device.

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Identified Risks to Health	Mitigation Measures
Risk of false results	Certain labeling information includinglimitations, device descriptions, explanationsof procedures and performance informationidentified in special controls (1) and (4).Use of certain specimen collection devicesidentified in special control (3).Certain design verification and validationincluding documentation of devicedescriptions, certain analytical studies andclinical studies, risk analysis strategiesidentified in special control (5).Testing of characterized viral samples andlabeling information identified in specialcontrol (6).
Failure to correctly interpret test results	Certain labeling information includinglimitations, device descriptions, explanationsof procedures and performance informationidentified in special controls (1) and (4).Use of certain specimen collection devicesidentified in special control (3).Certain design verification and validationincluding documentation of devicedescriptions, certain analytical studies andclinical studies, risk analysis strategiesidentified in special control (5).
Failure to correctly operate the device	Certain labeling information includinglimitations, device descriptions, explanationsof procedures and performance informationidentified in special controls (1), (2), and (4).Use of certain specimen collection devicesidentified in special control (3)

IX Benefit/Risk Assessment:

A Summary of the Assessment of Benefit:

The evidence provided indicates that this assay will appropriately diagnose SARS-CoV-2. This assay was validated more vigorously as compared to an EUA device to support a full authorization and classification as a Class II device. An added benefit is the ability to use the Sofia 2 device, a device which has previous 510(k) clearance and is used in CLIA waived settings, for use in reading the antigen result.

B Summary of the Assessment of Risk:

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The risks associated with the device. when used as intended, are those related to the risk of false test results, failure to correctly interpret the test results, and failure to correctly operate the device. False positive SARS-CoV-2 results may lead to include improper patient management, including treatment for SARS-CoV-2 with antiviral medication, monoclonal antibody treatment, or convalescent plasma. False positive SARS-CoV-2 results may also lead to unnecessary isolation or quarantine and additional health monitoring, mis-allocation of resources used for surveillance and prevention, and delayed diagnosis and treatment of other infections or health conditions. False negative SARS-CoV-2 results may lead to missing and not appropriately treating or monitoring a patient who has SARS-CoV-2 infection. False negative SARS-CoV-2 results may also lead to unnecessary additional diagnostic evaluation or treatment and delay in correct diagnosis or further spread of disease, which may lead to novel cases of infection and concomitant increase in patient morbidity and mortality.

C Summary of the Assessment of Benefit-Risk:

The clinical benefits outweigh the probable risk of false negative results for the proposed assay, considering the product labeling, special controls, as well as general controls. The clinical benefits of the assay include ease of use for the healthcare provider and instrument read results. Additionally of clinical benefit, the validation data suggests that errors will be uncommon and will facilitate accurate assay implementation and interpretation of results. The device's performance observed in the clinical study, including with the Omicron variant of SARS-CoV-2, suggests that errors will be uncommon and are mitigated by the device on-screen instructions which instruct the user on initial data entry and correct placement of the cartridge. Given that the assay cartridge cannot be visually interpreted. the user interface reports test result therefore reducing the possibility of incorrect visual interpretation of a lateral flow device. This assay will provide substantial benefits to patients and healthcare providers as an aid in the diagnosis of SARS-CoV-2 when used in conjunction with other laboratory results and clinical information.

X Conclusion:

The De Novo request is granted and the device is classified under the following Regulation and subject to the special controls identified in the letter granting the De Novo request:

Product Code(s):	QVF
Device Type:	Simple point-of-care device to directly detect SARS-CoV-2 viral targetsfrom clinical specimens in near-patient settings
Class:	Class II
Regulation:	21 CFR 866.3982

Regulation Number and Section

N/A