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The DiaSorin Molecular Simplexa™ Flu A/B & RSV Direct Gen II assay is intended for use on the LIAISON® MDX instrument for the in vitro qualitative detection and differentiation of influenza B virus, and respiratory syncytial virus (RSV) RNA in nasopharyngeal swabs (NPS) from human patients with signs and symptoms of respiratory tract infection in conjunction with clinical and epidemiological risk factors. This test is intended for use as an aid in the differential diagnosis of influenza A. influenza B. and RSV viral infections in humans.

Negative results do not preclude influenza virus or RSV infection and should not be used as the sole basis for treatment or other patient management decisions.

Performance characteristics for influenza A were established with clinical specimens collected during the 2010/2011 influenza season when 2009 H1N1 influenza and H3N2 were the predominant influenza A viruses in circulation. When other influenza A viruses are emerging, performance characteristics may vary.

If infection with a novel influenza A virus is suspected based on current clinical and epidemiological screening criteria recommended by public health authorities, specimens should be collected with appropriate infection control precautions for novel virulent Influenza viruses and sent to the state or local health department for testing. Viral culture should not be attempted in these cases unless a BSL 3+ facility is available to receive and culture specimens.

The DiaSorin Molecular Simplexa™ Flu A/B & RSV Positive Control Pack is intended to be used as a control with the Simplexa™ Flu A/B & RSV Direct kit and the Simplexa™ Flu A/B & RSV Direct Gen II kit for use on the LIAISON® MDX instrument. This control is not intended for use with other assays or systems.

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The provided document is a 510(k) clearance letter from the FDA for the DiaSorin Molecular Simplexa™ Flu A/B & RSV Direct Gen II assay. It primarily focuses on the device's regulatory clearance and indications for use, not on the detailed study results and acceptance criteria for performance evaluation.

Therefore, I cannot extract the detailed information requested in your prompt regarding acceptance criteria and performance study specifics from this document. The document states that the device is "substantially equivalent" to a legally marketed predicate device, implying that its performance was assessed, but the actual data and criteria are not included here.

To provide the answers you're looking for, I would need a different type of document, such as a summary of safety and effectiveness data (SSED) or the actual clinical study report that was submitted to the FDA for review.

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The Focus Diagnostics Simplexa™ Flu A/B & RSV Direct assay is intended for use on the 3M Integrated Cycler instrument for the in vitro qualitative detection and differentiation of influenza B virus, and respiratory syncytial virus (RSV) RNA in nasopharyngeal swabs (NPS) from human patients with signs and symptoms of respiratory tract infection in conjunction with clinical and epidemiological risk factors. This test is intended for use as an aid in the differential diagnosis of influenza B, and RSV viral infections in humans and is not intended to detect influenza C.

Negative results do not preclude influenza virus or RSV infection and should not be used as the sole basis for treatment or other patient management decisions.

Performance characteristics for influenza A were established with clinical specimens collected during the 2010/2011 influenza season when 2009 H1N1 influenza and H3N2 were the predominant influenza A viruses in circulation. When other influenza A viruses are emerging, performance characteristics may vary.

If infection with a novel Influenza A virus is suspected based on current clinical and epidemiological screening criteria recommended by public health authorities, specimens should be collected with appropriate infection control precautions for novel virulent influenza viruses and sent to the state or local health department for testing. Viral culture should not be attempted in these cases unless a BSL 3+ facility is available to receive and culture specimens.

Focus Diagnostics' Simplexa™ Flu A/B & RSV Positive Control Pack is intended to be used as a control with the Simplexa™ Flu A/B & RSV Direct kit. This control is not intended for use with other assays or systems.

The Simplexa™ Flu AB & RSV Direct assay system is a real-time RT-PCR system that enables the direct amplification, detection and differentiation of human influenza A (Flu A) virus RNA, human influenza B (Flu B) virus RNA and RSV RNA from unprocessed nasopharyngeal swabs that have not undergone nucleic acid extraction. The system consists of the Simplexa™ Flu A/B & RSV Direct assay, the 3M Integrated Cycler (with Integrated Cycler Studio Software), the Direct Amplification Disc and associated accessories.

In the Simplexa™ Flu A/B & RSV Direct assay, bi-functional fluorescent probe-primers are used together with corresponding reverse primers to amplify Flu A, Flu B, RSV and internal control RNA. The assay provides three results; conserved regions of influenza A viruses (matrix gene), influenza B viruses (matrix gene) and RSV (M gene) are targeted to identify these viruses in the specimen. An RNA internal control is used to detect RT-PCR failure and/or inhibition.

Here's a summary of the acceptance criteria and the study information for the Simplexa™ Flu A/B & RSV Direct device, based on the provided document:

Acceptance Criteria and Device Performance Study

The purpose of this Special 510(k) (K152408) is to expand the analytical reactivity of the Simplexa™ Flu A/B & RSV Direct assay to include 53 additional strains. Therefore, the primary acceptance criteria for this specific submission relate to the successful detection of these new strains.

1. Table of Acceptance Criteria and Reported Device Performance

The core acceptance criterion for the additional strains is detection by the Simplexa™ Flu A/B & RSV Direct assay. All tested strains were successfully detected.

Note: The document explicitly states: "Fifty-three strains met the established acceptance criteria and passed validation testing. Analytical Reactivity will be expanded to add 53 additional strains." This confirms that the acceptance criteria for these specific strains was successful detection.

2. Sample Size Used for the Test Set and Data Provenance

• Test Set Sample Size: For each of the 53 additional strains, the testing was performed in triplicate. This means a total of 53 strains * 3 replicates = 159 individual tests were performed for this specific analytical reactivity study.
• Data Provenance: The strains were sourced from various locations and historical periods, indicating a focus on analytical validity and strain diversity rather than clinical performance from a specific population or region. Examples include strains like "A/California/4/2009", "A/Massachusetts/15/2013", "A/Japan/305/57", "B/Brisbane/33/2008", and "ATCC-2012-10". The study itself is an analytical study conducted in a lab setting, not a direct clinical study. The document doesn't specify the country of origin where the testing took place, but it's likely a controlled lab environment.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications

This study focuses on analytical reactivity, where the "ground truth" is the presence and identification of a specific viral strain at a known concentration. This type of ground truth does not typically involve expert clinical adjudication. The ground truth (i.e., confirmation of the viral strain and its concentration) would have been established by standard laboratory methods for viral culture, quantification (e.g., TCID50/mL, CEID50/mL, PFU/mL), and characterization, prior to being used in the Simplexa™ assay. The document does not specify the number or qualifications of experts involved in establishing this initial ground truth, as it's a standard process in virology.

4. Adjudication Method for the Test Set

No adjudication method (e.g., 2+1, 3+1) is described, as this is an analytical study evaluating device performance against known quantities of target analytes, not a clinical study requiring human interpretation or consensus for diagnosis. The "result" is the output of the RT-PCR system ("Flu A Detected," "Flu B Detected," "RSV Detected").

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

No MRMC comparative effectiveness study was done for this particular submission. This 510(k) is a "Special 510(k)" to expand analytical reactivity, not to re-evaluate or compare clinical effectiveness with human readers. The clinical performance characteristics were established in a previous submission (K142365).

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

Yes, a standalone performance study was done for the analytical reactivity. The study evaluated the ability of the Simplexa™ Flu A/B & RSV Direct assay system (algorithm/device only) to detect the specified viral strains. The results presented ("Flu A Detected," "Flu B Detected," "RSV Detected") are direct outputs from the device, with no human intervention in the detection process itself.

7. Type of Ground Truth Used

The ground truth used for this analytical reactivity study was based on known quantified viral material. This means:

• Viral Culture/Quantification: Viral samples were quantified using methods like TCID50/mL (Tissue Culture Infectious Dose 50%), CEID50/mL (Chicken Embryo Infectious Dose 50%), PFU/mL (Plaque Forming Units/mL), or using purified RNA at known concentrations (e.g., ng/µL, IU/mL).
• Strain Identification: The specific identity and subtype of each viral strain were confirmed through standard virological methods.
• These known viral materials were then spiked into a negative swab matrix to simulate clinical samples for testing.

8. Sample Size for the Training Set

The document does not provide details about the training set sample size. This submission (K152408) is an expansion of analytical reactivity and refers to the predicate device K142365 for most other performance characteristics, including clinical studies. RT-PCR assays typically do not have a "training set" in the machine learning sense, but rather a development and validation process during which assay parameters are optimized and locked.

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

Similar to point 8, the document does not specifically detail how a "training set ground truth" was established, as it's not a machine learning algorithm in the typical sense that would require a distinct training phase with labeled data in the way, for example, an image recognition AI would. The development of an RT-PCR assay involves optimization and validation studies using characterized viral isolates and clinical samples, where the "ground truth" for these samples is derived from:

• Reference Methods: Such as viral culture, sequencing, or other FDA-cleared assays.
• Expert Consensus: For clinical samples, expert microbiologists or virologists would confirm the presence/absence of target viruses using gold standard methods.

The current document focuses singularly on the analytical reactivity towards an expanded panel of viral strains, relying on the already established methodologies from the predicate device (K142365) for other aspects of performance.

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The Focus Diagnostics Simplexa™ Flu A/B & RSV Direct assay is intended for use on the 3M Integrated Cycler instrument for the in vitro qualitative detection and differentiation of influenza B virus, and respiratory syncytial virus (RSV) RNA in nasopharyngeal swabs (NPS) from human patients with signs and symptoms of respiratory tract infection in conjunction with clinical and epidemiological risk factors. This test is intended for use as an aid in the differential diagnosis of influenza B, and RSV viral infections in humans and is not intended to detect influenza C.

Negative results do not preclude influenza virus or RSV infection and should not be used as the sole basis for treatment or other patient management decisions.

Performance characteristics for influenza A were established with clinical specimens collected during the 2010/2011 influenza season when 2009 H1N1 influenza and H3N2 were the predominant influenza A viruses in circulation. When other influenza A viruses are emerging, performance characteristics may vary.

If infection with a novel Influenza A virus is suspected based on current clinical and epidemiological screening criteria recommended by public health authorities, specimens should be collected with appropriate infection control precautions for novel virulent Influenza viruses and sent to the state or local health department for testing. Viral culture should not be attempted in these cases unless a BSL 3+ facility is available to receive and culture specimens.

Simplexa™ Flu A/B & RSV Positive Control Pack REF MOL2660

Focus Diagnostics' Simplexa™ Flu A/B & RSV Positive Control Pack is intended to be used as a control with the SimplexaTM Flu A/B & RSV Direct kit. This control is not intended for use with other assays or systems.

The Simplexa™ Flu A/B & RSV Direct assay system is a real-time RT-PCR system that enables the direct amplification, detection and differentiation of human influenza A (Flu A) virus RNA, human influenza B (Flu B) virus RNA and RSV RNA from unprocessed nasopharyngeal swabs that have not undergone nucleic acid extraction. The system consists of the Simplexa™ Flu A/B & RSV Direct assay, the 3M Integrated Cycler (with Integrated Cycler Studio Software), the Direct Amplification Disc and associated accessories.

In the Simplexa™ Flu A/B & RSV Direct assay, bi-functional fluorescent probe-primers are used together with corresponding reverse primers to amplify Flu A, Flu B, RSV and internal control RNA. The assay provides three results; conserved regions of influenza A viruses (matrix gene), influenza B viruses (matrix gene) and RSV (M gene) are targeted to identify these viruses in the specimen. An RNA internal control is used to detect RT-PCR failure and/or inhibition.

The provided text describes a 510(k) summary for the Simplexa™ Flu A/B & RSV Direct and Simplexa™ Flu A/B & RSV Positive Control Pack. This submission is intended to add eight additional influenza strains to the analytical reactivity of the device and addresses modifications made to the device from an earlier version (K120413).

Here's a breakdown of the requested information based on the document:

1. Table of acceptance criteria and the reported device performance

The document does not explicitly state "acceptance criteria" in the format of pass/fail thresholds for clinical performance. Instead, it presents "Positive Percent Agreement (PPA)" and "Negative Percent Agreement (NPA)" with a predicate device (Gen 1.0) and between device versions (Gen 2.0 and Gen 2.1) as part of method comparison studies, along with analytical reactivity and specificity data.

Method Comparison Results (Performance in relation to K120413 and between versions)

Analytical Reactivity (Gen 2.1): All tested influenza A, influenza B, and RSV strains at specified concentrations were detected (100% detection for all, assayed in triplicate). These include:

• 18 Influenza A strains (H1, H3, H7N9)
• 10 Influenza B strains
• 4 RSV strains (A and B)

Cross Reactivity (Analytical Specificity) (Gen 2.1): No cross-reactivity was observed with 32 tested organisms (bacteria and other viruses) at clinically relevant concentrations. All results showed 0% detection for Flu A, Flu B, and RSV, and 100% detection for the Internal Control.

Interference (Gen 2.1): No evidence of interference was observed from potentially interfering substances (e.g., nasal sprays, antiviral drugs, blood, mucin protein) tested in contrived samples. All showed 100% detection for Flu A, Flu B, RSV, and RNA IC.

Limit of Detection (LoD) (Gen 2.1): The LoD for various strains across Gen 1.0, Gen 2.0, and Gen 2.1 are provided (e.g., Influenza A/Hong Kong/8/68 (H3N2) Gen 2.1 LoD: 0.1 TCID50/mL). The criteria for LoD determination was ≥95.0% detection (at least 31/32 replicates).

Precision (Gen 2.1): High reproducibility (low %CV) was observed for Ct values across inter-day, inter-run, inter-lot, and intra-run/lot variations for low and moderate positive samples of Flu A, Flu B, and RSV, as well as positive and negative controls. Qualitatively, all expected positive samples were detected at 100%, and negative samples were not detected for the target analytes.

2. Sample size used for the test set and the data provenance

• Sample Size (Method Comparison): For each comparison (Gen 1.0 vs Gen 2.0, and Gen 2.0 vs Gen 2.1), 265 archived clinical samples were used.

  • Composition: 55 positive for influenza A, 55 positive for influenza B, 55 positive for RSV, and 100 negative for all tested viruses.
  • Data Provenance: The samples were "archived clinical samples" in Universal Transport Medium (UTM) or Viral Transport Medium (VTM).
    • 131 of these samples for the Gen 1.0 vs Gen 2.0 comparison were originally tested in support of K120413. The remaining 134 included 33 from the 2010-2011 flu season and 101 from the 2013-2014 flu season.
    • For the Gen 2.0 vs Gen 2.1 comparison, 125 samples were from K120413 study. The remaining 140 included 48 from the 2010-2011 flu season, 9 from 2012-2013, and 83 from 2013-2014.
    • The country of origin is not specified, but the context implies data likely from the USA (given FDA submission). The data is retrospective as it uses archived samples.

• Sample Size (Analytical Reactivity/Cross Reactivity/Interference):

  • Analytical Reactivity: Each viral strain was assayed in triplicate.
  • Cross Reactivity: Each organism was tested in triplicate (3 replicates). Baseline negative matrix was tested in five (5) replicates.
  • Interference: Each interfering substance was tested in triplicate (3 replicates). Baseline was tested in 15 replicates.
  • Limit of Detection: Initially, 4 concentrations per virus tested in triplicate. Confirmatory testing involved 32 replicates for the lowest concentration.
  • Precision: Each sample panel member tested in duplicate for each Reaction Mix lot in each run, two runs per day for a total of three days, yielding at least 36 replicates per panel member (41 for one Flu B sample).

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts

The document does not explicitly state the use of "experts" to establish ground truth for the test set in the method comparison studies. The ground truth for these studies appears to be based on results from the predicate device (Simplexa™ Flu A/B & RSV Direct Gen 1.0) and/or other FDA cleared Nucleic Acid Tests (NATs) for discrepant samples. For analytical studies (reactivity, cross-reactivity, interference, LoD, precision), the ground truth is established by the known concentration/presence of the spiked organisms or substances.

4. Adjudication method for the test set

For the method comparison studies, discrepancies between the modified device (Gen 2.0 or Gen 2.1) and the predicate device (Gen 1.0 or Gen 2.0 respectively) were sometimes resolved using another FDA cleared NAT. For example, for Flu A discrepancies in the Gen 1.0 vs Gen 2.0 comparison, "7/9 discrepant (K120413 – Negative and K142365 – Positive) samples were positive for Flu A on another FDA cleared NAT." This suggests a form of adjudication using a third, independent, cleared method.

5. If a multi-reader multi-case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance

This section is not applicable. The device described is an in vitro diagnostic (IVD) assay for the detection of viruses using real-time RT-PCR, not an AI-powered diagnostic imaging device involving human readers or interpretation of medical images. Therefore, MRMC studies and the concept of human reader improvement with AI assistance do not apply.

6. If a standalone (i.e., algorithm only without human-in-the-loop performance) was done

This concept is not directly applicable in the context of an IVD assay like the Simplexa™ Flu A/B & RSV Direct. The device is essentially a "standalone" algorithm/assay from the perspective of direct human interpretation providing a qualitative result (detected/not detected). The performance metrics (PPA, NPA, analytical reactivity, LoD, etc.) represent the standalone performance of the assay system. There is no human "in the loop" for interpreting the raw assay output; the instrument's software interprets the Ct values to provide a qualitative result.

7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.)

• Clinical Studies (Method Comparison): The ground truth for the clinical sample comparisons was based on:
  • The performance of the predicate device (Simplexa™ Flu A/B & RSV Direct Gen 1.0) for direct comparison between versions.
  • Other FDA cleared Nucleic Acid Tests (NATs) for resolving discrepant results between the device versions.
• Analytical Studies (Reactivity, Cross-Reactivity, Interference, LoD, Precision): The ground truth was established by known spiked concentrations of characterized viral strains, bacterial organisms, or potentially interfering substances into negative matrix.

8. The sample size for the training set

The document does not explicitly mention a "training set" in the context of machine learning or AI models, as this is an IVD assay. The development and optimization ("changes to the reaction mix formulation and cycling conditions," "changes to the manufacturing process and materials") that led to Gen 2.0 and Gen 2.1 would have involved internal validation and optimization data, which could be considered analogous to training data in a broad sense for assay development. However, specific "training set sizes" are not provided.

9. How the ground truth for the training set was established

As described in point 8, a formal "training set" for an AI model is not applicable here. For the assay development and optimization, ground truth would have been established through controlled laboratory experiments using well-characterized viral isolates and defined concentrations, analogous to how ground truth for the analytical studies (reactivity, LoD) was established.

Ask a specific question about this device

The Focus Diagnostics Simplexa™ Flu A/B & RSV Direct assay is intended for use on the 3M Integrated Cycler instrument for the in vitro qualitative detection and differentiation of influenza A virus, influenza B virus, and respiratory syncytial virus (RSV) RNA in nasopharyngeal swabs (NPS) from human patients with signs and symptoms of respiratory tract infection in conjunction with clinical and epidemiological risk factors. This test is intended for use as an aid in the differential diagnosis of influenza A, influenza B, and RSV viral infections in humans and is not intended to detect influenza C.

Negative results do not preclude influenza virus or RSV infection and should not be used as the sole basis for treatment or other patient management decisions.

Performance characteristics for influenza A were established with clinical specimens collected during the 2010/2011 influenza season when 2009 H1N1 influenza and H3N2 were the predominant influenza A viruses in circulation. When other influenza A viruses are emerging, performance characteristics may vary.

If infection with a novel Influenza A virus is suspected based on current clinical and epidemiological screening criteria recommended by public health authorities, specimens should be collected with appropriate infection control precautions for novel virulent Influenza viruses and sent to the state or local health department for testing. Viral culture should not be attempted in these cases unless a BSL 3+ facility is available to receive and culture specimens.

Focus Diagnostics' Simplexa™ Flu A/B & RSV Positive Control Pack is intended to be used as a control with the Simplexa™ Flu A/B & RSV Direct kit. This control is not intended for use with other assays or systems.

The Simplexa™ Flu A/B & RSV Direct assay system is a real-time RT-PCR system that enables the direct amplification, delection and differentiation of human influenza A (Flu A) virus RNA, human influenza B (Flu B) virus RNA and RSV RNA from unprocessed nasopharyngeal swabs that have not undergone nucleic acid extraction. The system consists of the Simplexa™ Flu A/B & RSV Direct assay, the 3M Integrated Cycler (with Integrated Cycler Studio Software), the Direct Amplification Disc and associated accessories.

In the Simplexa™ Flu A/B & RSV Direct assay, bi-functional fluorescent probe-primers are used together with corresponding reverse primers to amplify Flu A, Flu B, RSV and internal control RNA. The assay provides three results; conserved regions of influenza A viruses (matrix gene) influenza B viruses (matrix gene) and RSV (M gene) are targeted to identify these viruses in the specimen. An RNA internal control is used to detect RT-PCR failure and/or inhibition.

The 3M Integrated Cycler is a rapid real-time Polymerase Chain Reaction thermocycler used for the identification of nucleic acid from prepared biological samples. The instrument utilizes disk media to contain and to process samples. The instrument uses real time flourometric detection to identify targets within the sample wells. The instrument is controlled by an external computer running the Integrated Cycler Studio software.

Here's a breakdown of the acceptance criteria and study details for the Simplexa™ Flu A/B & RSV Direct assay, based on the provided 510(k) summary:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria are not explicitly stated as numerical targets in the document. However, the reported performance data from the clinical studies serve as the basis for demonstrating the device's acceptable performance. For clarity, I've listed the reported performance as if those were the implicit acceptance targets for the study.

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The Focus Diagnostics Simplexa™ Flu A/B & RSV assay is intended for use on the 3M Integrated Cycler instrument for the in vitro qualitative detection and discrimination of influenza A virus, influenza B virus, and respiratory syncytial virus (RSV) RNA in nasopharyngeal swabs (NPS) from human patients with signs and symptoms of respiratory tract infection in conjunction with clinical and epidemiological risk factors. This test is intended for use as an aid in the differential diagnosis of influenza A, influenza B, and RSV viral infections in humans and is not intended to detect influenza C.

Negative results do not preclude influenza virus or RSV infection and should not be used as the sole basis for treatment or other patient management decisions.

Performance characteristics for influenza A were established during the 2010 influenza season when 2009 H1N1 influenza was the predominant influenza A virus in circulation. When other influenza A viruses are emerging, performance characteristics may vary.

If infection with a novel Influenza A virus is suspected based on current clinical and epidemiological screening criteria recommended by public health authorities, specimens should be collected with appropriate infection control precautions for novel virulent Influenza viruses and sent to state or local health department for testing. Viral culture should not be attempted in these cases unless a BSL 3+ facility is available to receive and culture specimens.

The test is a real-time RT-PCR amplification system that utilizes a bi-functional fluorescent probe-primer for the detection and differentiation of human influenza A virus RNA, human influenza B virus RNA and respiratory syncytial virus RNA in nasopharyngeal swabs (NPS). The assay is composed of two principal steps: (1) extraction of RNA from patient specimens, (2) A bi-functional fluorescent probe-primer is used together with a reverse primer to amplify a specific target (for each analyte and the RNA internal control). The assay provides three results; conserved regions of influenza A viruses (matrix gene), influenza B viruses (matrix gene) and RSV (M gene) are targeted to identify these viruses in the specimen. An RNA internal control is used to monitor the extraction process and to detect RT-PCR inhibition.

The 3M Integrated Cycler is a rapid real-time Polymerase Chain Reaction thermocycler used for the identification of nucleic acid from prepared biological samples. The instrument utilizes disk media to contain and to process samples. The instrument uses real time flourometric detection to identify targets within the sample wells. The instrument is controlled by an external computer running the Integrated Cycler Studio Software.

The Focus Diagnostics Simplexa™ Flu A/B & RSV assay is intended for the qualitative detection and discrimination of influenza A virus, influenza B virus, and respiratory syncytial virus (RSV) RNA in nasopharyngeal swabs (NPS).

Here's an analysis of the provided information:

1. Table of Acceptance Criteria and Reported Device Performance:

The document doesn't explicitly state "acceptance criteria" as distinct numerical thresholds for PPA/NPA. Instead, it provides the clinical agreement percentages, which are implicitly the performance targets for demonstrating substantial equivalence. The table below summarizes the reported clinical agreement from the clinical agreement study for both prospective and retrospective samples.

2. Sample size used for the test set and the data provenance:

• Total Sample Size: 735 nasopharyngeal swabs (NPS).
• Provenance:
  • Prospective Samples: 558 specimens, collected from patients with signs and symptoms of viral respiratory tract infection.
  • Retrospective Samples: An unspecified number (the document mentions "banked specimens with signs and symptoms of viral respiratory tract infection," and the individual category summaries provide the counts for retrospective testing: 177 for Influenza A, 177 for Influenza B, and 177 for RSV). The combined numbers in the tables (e.g., 553 for prospective Flu A, 553 for prospective Flu B, etc.) indicate how the 558 prospective samples were distributed across the different analytes, and similarly for retrospective samples from the total of 735.
• Country of Origin: Not explicitly stated, but typically for FDA submissions, these studies are conducted in the US.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:

This information is not provided in the document. The ground truth was established by laboratory methods, not expert visual assessment.

4. Adjudication method for the test set:

This information is not applicable as the ground truth was established by reference laboratory methods (high-performance NAT and culture/DFA), not by human interpretation requiring adjudication.

5. If a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was done, if so, what was the effect size of how much human readers improve with AI vs without AI assistance:

Not applicable. This study is for an in vitro diagnostic device (RT-PCR assay), not an imaging-based AI diagnostic that typically involves human readers. Therefore, an MRMC study and analysis of human reader improvement with AI assistance were not performed.

6. If a standalone (i.e., algorithm only without human-in-the-loop performance) was done:

Yes, this was effectively a standalone study. The Simplexa™ Flu A/B & RSV assay is an automated RT-PCR system. Its performance was compared directly against reference methods (high-performance NAT and culture/DFA) without human interpretation steps that would integrate with the device's output. The device itself is the "standalone algorithm/system."

7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.):

• Influenza A Virus: High performance FDA cleared nucleic acid test (NAT).
• Influenza B Virus: High performance FDA cleared nucleic acid test (NAT).
• Respiratory Syncytial Virus (RSV): Culture/DFA (Direct Fluorescent Antibody).

8. The sample size for the training set:

The document does not explicitly mention a "training set" in the context of device development. This is typical for in vitro diagnostic assays like RT-PCR, where analytical performance (e.g., Limit of Detection, analytical reactivity, cross-reactivity) is established using characterized strains and then clinical performance is validated on clinical samples, rather than a machine learning training/validation split.

9. How the ground truth for the training set was established:

As no explicit "training set" or machine learning approach is described for the device, this information is not applicable. The analytical characteristics are determined using known concentrations of viral strains and the clinical performance is compared against established reference methods.

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