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The Influenza A/B Typing Kit contains reagents and controls of the CDC Human Influenza Virus Real-Time RT-PCR Diagnostic Panel and is intended for use in real-time RT-PCR (rRT-PCR) assays on an in vitro diagnostic real-time PCR instrument that has been FDA-cleared for use with this kit in conjunction with clinical and epidemiological information:

• For qualitative detection of influenza virus type A or B viral RNA in upper respiratory tract clinical specimens (including nasopharyngeal swabs [NPS], nasal swabs [NS], throat swabs [TS], nasal aspirates [NA], nasal washes [NW] and dual nasopharyngeal/throat swabs [NPS/TS]) and lower respiratory tract specimens (including bronchoalveolar lavage [BAL], bronchial wash [BW], tracheal aspirate [TA], sputum, and lung tissue) from human patients with signs and symptoms of respiratory infection and/or from viral culture.

• To provide epidemiological information for surveillance of circulating influenza viruses.

Performance characteristics for influenza were established during a season when seasonal influenza viruses A(H1N1) and A(H3N2) were the predominant influenza A viruses in circulation and during a season when the A(H1N1)pdm09 influenza virus was the predominant influenza A virus in circulation. Performance characteristics may vary with other emerging influenza A viruses.

Negative results do not preclude influenza virus infection and should not be used as the sole basis for treatment or other patient management decisions. Conversely, positive results do not rule out bacterial infection or co-infection with other viruses. The agent detected may not be the definite cause of disease.

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 unless a BSL 3E facility is available to receive and culture specimens.

CDC Human Influenza Real-Time RT-PCR Diagnostic Panel: Influenza A Subtyping Kit (VER 4)

The Influenza A Subtyping Kit contains reagents and controls of the CDC Human Influenza Virus Real-Time RT-PCR Diagnostic Panel and is intended for use in real-time RT-PCR (rRT-PCR) assays on an in vitro diagnostic real-time PCR instrument that has been FDA-cleared for use with this kit in conjunction with clinical and epidemiological information:

• For determination of the subtype of seasonal human influenza A viruses as seasonal A(H3) and/or A(H1)pdm09 from viral RNA in upper respiratory tract clinical specimens (including nasopharyngeal swabs [NPS], nasal swabs [NS], throat swabs [TS], nasal aspirates [NA], nasal washes [NW] and dual nasopharyngeal/throat swabs [NPS/TS]) and lower respiratory tract specimens (including bronchoalveolar lavage [BAL], bronchial wash [BW], tracheal aspirate [TA], sputum, and lung tissue) from human patients with signs and symptoms of respiratory infection and/or from viral culture;

• To provide epidemiological information for surveillance of circulating influenza viruses.

Performance characteristics for influenza were established during a season when seasonal influenza viruses A(H1N1) and A(H3N2) were the predominant influenza A viruses in circulation and during a season when the A(H1N1)pdm09 influenza virus was the predominant influenza A virus in circulation. Performance characteristics may vary with other emerging influenza A viruses.

Negative results do not preclude influenza virus infection and should not be used as the sole basis for treatment or other patient management decisions. Conversely, positive results do not rule out bacterial infection or co-infection with other viruses. The agent detected may not be the definite cause of disease.

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 unless a BSL 3E facility is available to receive and culture specimens.

CDC Human Influenza Virus Real-Time RT-PCR Diagnostic Panel: Influenza B Lineage Genotyping Kit (VER 1.1 and 2)

The Influenza B Lineage Genotyping Kit contains reagents and controls of the CDC Human Influenza Virus Real-Time RT-PCR Diagnostic Panel and is intended for use in real-time RT-PCR (rRT-PCR) assays on an in vitro diagnostic real-time PCR instrument that has been FDA-cleared for use with this kit in conjunction with clinical and epidemiological information:

• For the determination of the genetic lineage of human influenza B viruses as B/Victoria or B/Yamagata lineage from viral RNA in upper respiratory tract clinical specimens (including nasopharyngeal swabs [NPS], nasal swabs [NS], throat swabs [TS], nasal aspirates [NA], nasal washes [NW] and dual nasopharyngeal/throat swabs [NPS/TS]) from human patients with signs and symptoms of respiratory infection and/or from viral culture;

• To provide epidemiologic information for surveillance of circulating influenza viruses.

Performance characteristics for influenza B lineage genotyping were established during a season when influenza B/Victoria and B/Yamagata lineages were in circulation.

Negative results do not preclude influenza virus infection and should not be used as the sole basis for treatment or other patient management decisions. Conversely, positive results do not rule out bacterial infection or co-infection with other viruses. The agent detected may not be the definite cause of disease.

CDC Human Influenza Virus Real-Time RT-PCR Diagnostic Panel: Influenza A/H5 Subtyping Kit (VER 4)

The Influenza A/H5 Subtyping Kit contains reagents and controls of the CDC Human Influenza Virus Real-Time RT-PCR Diagnostic Panel and is intended for use in real-time RT-PCR (rRT-PCR) assays on an in vitro diagnostic real-time PCR instrument that has been FDA-cleared for use with this kit in conjunction with clinical and epidemiological information:

• For the presumptive identification of virus in patients who may be infected with influenza A subtype A(H5) (Asian lineage) from viral RNA in human respiratory specimens, conjunctival swabs, and viral culture in conjunction with clinical and epidemiological risk factors;

• To provide epidemiologic information for surveillance of circulating influenza viruses.

Performance characteristics for influenza were established during a season when seasonal influenza viruses A(H1N1) and A(H3N2) were the predominant influenza A viruses in circulation and during a season when the A(H1N1)pdm09 influenza virus was the predominant influenza A virus in circulation. Performance characteristics may vary with other emerging influenza A viruses.

Testing with the influenza H5a and H5b primer and probe sets should not be performed unless the patient meets the most current U.S.Department of Health and Human Services (DHHS) clinical and epidemiologic criteria for testing suspect A(H5) specimens. The definitive identification of influenza A(H5) (Asian lineage) either directly from patient specimens or from virus cultures requires additional laboratory testing, along with clinical and epidemiological assessment in consultation with national influenza surveillance experts.

Negative results do not preclude influenza virus infection and should not be used as the sole basis for treatment or other patient management decisions. Conversely, positive results do not rule out bacterial infection or co-infection with other viruses. The agent detected may not be the definite cause of disease.

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 unless a BSL 3E facility is available to receive and culture specimens.

The CDC Human Influenza Real-Time RT-PCR Diagnostic Panel is used in real-time RT-PCR (rRT-PCR) assays on an in vitro diagnostic real-time PCR instrument that has been FDA-cleared for use with the CDC device. The panel is configured in four separate kits. Each kit consists of oligonucleotide primers, fluorescently labeled hydrolysis probes, and controls which are used in rRT-PCR assays for the in vitro qualitative detection and characterization of influenza virus RNA in respiratory specimens from patients presenting with influenza-like illness (ILI) or from viral culture.

Oligonucleotide primers and probes for detection of influenza A, influenza B, and influenza A of swine origin were selected from highly conserved regions of the matrix (M), non-structural (NS), and nucleoprotein (NP) genes, respectively. Oligonucleotide primers and probes for characterization and differentiation of influenza A(H3) and A(H1)pdm09 viruses, avian influenza A(H5) viruses, and genetic lineages of influenza B were selected from highly conserved regions of their hemagglutinin (HA) genes. Oligonucleotide primers and probes to detect the human RNase P gene (RP) in control samples and clinical specimens is also included in the panel.

The provided document, K243274: CDC Human Influenza Virus Real-Time RT-PCR Diagnostic Panel, is an FDA 510(k) clearance letter. This document primarily describes the device, its intended use, and confirms its substantial equivalence to a previously cleared predicate device (K243931). Critically, it states that no analytical or clinical testing was performed for this specific modification, as the submission was to add a Predetermined Change Control Plan (PCCP).

Therefore, the document does not contain the detailed study results, acceptance criteria, sample sizes, ground truth establishment, or expert involvement for the original validation of the device's performance. It explicitly states that "The performance characteristics of the CDC Flu rRT-PCR Dx Panel... were previously established and remain the same as the predicate device (K243931)."

As such, I cannot provide the specific information requested in the prompt based on the provided text alone. The prompt asks for details of "the device" meeting acceptance criteria, and this document pertains to a modification that did not involve re-evaluating performance.

However, I can interpret what would typically be sought for such an analysis in the context of an in vitro diagnostic (IVD) PCR panel like the one described. I will outline what the acceptance criteria and the study that proves the device meets them would likely entail for an IVD, but with the explicit understanding that the provided document does not contain these details.

Based on the provided document, the device's performance characteristics were "previously established" for the predicate device (K243931) and are simply carried over here as "remaining the same." The current submission (K243274) is for adding a Predetermined Change Control Plan (PCCP) and states that "No analytical testing was performed for this modification" and "No clinical testing was performed for this modification."

Therefore, the detailed information regarding acceptance criteria, reported performance, sample sizes, expert involvement, and ground truth establishment for the original validation of this device is NOT present in the provided text. The tables and descriptions below represent what would typically be expected for an FDA cleared RT-PCR diagnostic panel, assuming the original studies were conducted to industry standards, but are not extracted directly from the given document.

Acceptance Criteria and Device Performance (Hypothetical for an RT-PCR IVD)

For a real-time RT-PCR diagnostic panel like the CDC Human Influenza Virus Panel, acceptance criteria and performance would typically focus on analytical sensitivity (Limit of Detection - LoD), analytical specificity (cross-reactivity, inclusivity), and clinical performance (sensitivity, specificity).

1. Table of Acceptance Criteria and Reported Device Performance (Hypothetical)

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CDC Human Influenza Real-Time RT-PCR Diagnostic Panel: Influenza A/B Typing Kit (VER 2)

The Influenza A/B Typing Kit contains reagents and controls of the CDC Human Influenza Virus RT-PCR Diagnostic Panel and is intended for use in real-time RT-PCR (rRT-PCR) assays on an in vitro diagnostic real-time PCR instrument that has been FDA-cleared for use with this kit in conjunction with clinical and evidemiological information:

· For qualitative detection of influenza virus type A or B viral RNA in upper respiratory tract clinical specimens (including nasopharyngeal swabs [NPS], throat swabs [TS], nasal aspirates [NA], nasal washes [NW and dual nasopharyngeal/throat swabs [NPS/TS]) and lower respiratory tract specimens (including bronchoalveolar lavage [BAL], bronchial wash [BW], tracheal aspirate [TA], sputum, and lung tissue) from human patients with signs and symptoms of respiratory infection and/or from viral culture.

· To provide epidemiological information for surveillance of circulating influenza viruses.

CDC Human Influenza Real-Time RT-PCR Diagnostic Panel: Influenza A Subtyping Kit (VER 4)

The Influenza A Subtyping Kit contains reagents and controls of the CDC Human Influenza Virus RT-PCR Diagnostic Panel and is intended for use in real-time RT-PCR (rRT-PCR) assays on an in vitro diagnostic real-time PCR instrument that has been FDA-cleared for use with this kit in conjunction with clinical and epidemiological information:

· For determination of the subtype of seasonal human influenza A viruses as seasonal A(H3) and/or A(H1)pdm09 from viral RNA in upper respiratory tract clinical specimens (including nasopharyngeal swabs [NS], throat swabs [TS], nasal aspirates [NA], nasal washes [NW] and dual nasopharyngeal/throat swabs [NPS/TS]) and lower respiratory tract specimens (including bronchoalveolar lavage [BAL], bronchial wash [BW], tracheal aspirate [TA], sputum, and lung tissue) from human patients with signs and symptoms of respiratory infection and/or from viral culture:

· To provide epidemiological information for surveillance of circulating influenza viruses.

CDC Human Influenza Virus Real-Time RT-PCR Diagnostic Panel: Influenza B Lineage Genotyping Kit (VER 1.1 and 2)

The Influenza B Lineage Genotyping Kit contains reagents and controls of the CDC Human Influenza Virus Real-Time RT-PCR Diagnostic Panel and is intended for use in real-time RT-PCR (rRT-PCR) assays on an in vitro diagnostic realtime PCR instrument that has been FDA-cleared for use with this kit in conjunction with clinical and epidemiological information:

• For the determination of the genetic lineage of human influenza B viruses as B/Victoria or B/Yamagata lineage from viral RNA in upper respiratory tract clinical specimens (including nasopharyngeal swabs [NS], throat swabs [TS], nasal aspirates [NA], nasal washes [NW] and dual nasopharyngeal/throat swabs [NPS/TS]) from human patients with signs and symptoms of respiratory infection and/or from viral culture;

· To provide epidemiologic information for surveillance of circulating influenza viruses.

CDC Human Influenza Virus Real-Time RT-PCR Diagnostic Panel: Influenza A/H5 Subtyping Kit (VER 4)

The Influenza A/H5 Subtyping Kit contains reagents and controls of the CDC Human Influenza Virus RT-PCR Diagnostic Panel and is intended for use in real-time RT-PCR (rRT-PCR) assays on an in vitro diagnostic real-time PCR instrument that has been FDA-cleared for use with this kit in conjunction with clinical and epidemiological information:

· For the presumptive identification of virus in patients who may be infected with influenza A subtype A(H5) (Asian lineage) from viral RNA in human respiratory specimens, conjunctival swabs, and viral culture in conjunction with clinical and epidemiological risk factors;

· To provide epidemiologic information for surveillance of circulating influenza viruses.

The CDC Human Influenza Real-Time RT-PCR Diagnostic Panel consists of four real-time RT-PCR (rRT-PCR) assays used on IVD-labeled real-time PCR instruments that has been FDA-cleared for use with this device. The panel is configured in four separate kits: Influenza A/B Typing kit, Influenza A/H5 Subtyping kit, and Influenza B Genotyping kit. Each kit consists of oligonucleotide primers, fluorescently labeled hydrolysis probes, and controls which are used in rRT-PCR assays for the in vitro qualitative detection of influenza virus RNA in respiratory and conjunctival specimens from patients presenting with influenza-like illness (IL). Oligonucleotide primers and probes for detection of influenza A, influenza B, and 2009 influenza A (swine origin) were selected from highly conserved regions of the matrix (M), non-structural (NS), and nucleoprotein (NP) genes, respectively. Oligonucleotide primers and probes for characterization and differentiation of influenza A(H3) and A(H1)pdm09 viruses, genetic lineages of influenza A(H5) viruses were selected from highly conserved regions of their HA genes. Oligonucleotide primers and probes to detect the human RNase P gene (RP) in control samples and clinical specimens are also included in the panel.

The provided text describes the acceptance criteria and study proving the device meets those criteria for the CDC Human Influenza Virus Real-Time RT-PCR Diagnostic Panel: Influenza A/H5 Subtyping Kit (VER 4), specifically concerning the addition of conjunctival swabs as a specimen type.

Here’s a breakdown of the requested information based on the provided text:

1. Table of acceptance criteria and the reported device performance:

The document does not explicitly present a table of acceptance criteria in terms of specific quantitative thresholds (e.g., minimum sensitivity/specificity percentages) for clinical performance. Instead, it describes an evaluation based on demonstrating successful detection capabilities and similarity to a predicate device. The performance is reported descriptively based on the clinical study results.

Reported Device Performance (for Influenza A/H5 Subtyping Kit (VER 4) on conjunctival swabs):

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

• Clinical Test Set Sample Size:
  • 46 total cases (44 confirmed, 2 probable) initially considered.
  • 35 confirmed cases were assessed for performance due to exclusion of 9 cases where not all necessary assay reagents were used.
  • 2 probable cases were assessed.
  • The document also specifies the number of clinical specimens available for testing: e.g., 32 confirmed cases had subject-matched paired URT and CS specimens, 3 confirmed cases had only CS specimens, 1 probable case had subject-matched paired URT and CS specimens, and 1 probable case had only a CS specimen.
• Data Provenance:
  • Country of Origin: US (from public health investigations in the US).
  • Retrospective or Prospective: The data was collected from specimens from March to November 2024 as part of public health investigations into outbreaks. This indicates a retrospective collection of existing specimens from human cases.

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

• The ground truth for confirmed/probable cases of A/H5N1 was established based on "the criteria described in the current Council of State and Territory Epidemiologists (CSTE) document 24-ID-09." The document does not specify the number of individual experts or their qualifications directly. This refers to established public health guidelines rather than individual expert consensus.

4. Adjudication method (e.g. 2+1, 3+1, none) for the test set:

• The ground truth was established by adherence to existing CSTE criteria, not through a human reader adjudication process of the device's output. The device results were compared against these established "confirmed or probable case status."

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:

• No, an MRMC comparative effectiveness study was not done. This document describes the validation of a laboratory diagnostic kit (RT-PCR) with specific specimen types and does not involve human readers interpreting images or AI assistance.

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

• Yes, this is effectively a standalone performance study. The device itself is an RT-PCR diagnostic panel. The "performance" described is that of the kit (reagents and controls run on a PCR instrument) in detecting viral RNA, without human interpretation of raw data beyond reading the instrument's output based on established cut-offs (e.g., Ct values). It's an "algorithm only" in the sense that the test results in a definitive positive, negative, or inconclusive outcome based on chemical reactions and signal detection.

7. The type of ground truth used:

• The ground truth for the clinical performance evaluation was based on "confirmed or probable case status for each case on the criteria described in the current Council of State and Territory Epidemiologists (CSTE) document 24-ID-09." This can be categorized as outcomes data/epidemiological criteria as determined by public health authorities.

8. The sample size for the training set:

• The document describes the validation of a diagnostic panel (PCR-based), not an AI algorithm. Therefore, there is no specific "training set" in the machine learning sense. The device's components (primers, probes) and their performance characteristics are established through analytical studies (e.g., LoD, interfering substances) and clinical validation with patient samples. The development of such a kit is based on extensive prior knowledge of influenza virus genetics and PCR technology, but not a "training set" in the context of supervised learning for AI.

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

• As there is no "training set" in the AI sense, this question is not applicable to the device described. The "ground truth" for the analytical development of the RT-PCR panel would be based on well-characterized viral samples (e.g., BPL inactivated virus with known concentrations) and established laboratory techniques for nucleic acid detection.

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The Influenza A Subtyping Kit contains reagents and controls of the CDC Human Influenza Virus Real-Time RT-PCR Diagnostic Panel and is intended for use in real-time RT-PCR (rRT-PCR) assays on an in vitro diagnostic real-time PCR instrument that has been FDA-cleared for use with this kit in conjunction with clinical and epidemiological information:

· For determination of the subtype of seasonal human influenza A viruses as seasonal A(H3) and/or A(H1)pdm09 from viral RNA in upper respiratory tract clinical specimens (including nasopharyngeal swabs [NS], throat swabs [TS], nasal aspirates [NA], nasal washes [NW] and dual nasopharyngeal/throat swabs [NPS/TS]) and lower respiratory tract specimens (including bronchoalveolar lavage [BAL], bronchial wash [BW], tracheal aspirate [TA], sputum, and lung tissue) from human patients with signs and symptoms of respiratory infection and/or from viral culture;

· To provide epidemiologic information for surveillance of circulating influenza viruses.

The Influenza A Subtyping Kit contains components of the CDC Human Influenza Virus Real-Time RT-PCR Diagnostic Panel that is used in rRT-PCR assays on an FDA-cleared in vitro diagnostic real-time PCR instrument. The primer and probe sets contained in the Influenza A Subtyping Kit are designed for the detection and characterization of influenza type A viruses that infect humans.

The Influenza A Subtyping Kit consists of oligonucleotide primers and dual-labeled hydrolysis (TagMan®) probes and controls. which may be used in rRT-PCR assays for the in vitro qualitative detection and characterization of the human influenza virus RNA in respiratory specimens from patients presenting with influenza-like illness (IL). The oligonucleotide primers and probes for detection of Influenza A and 2009 Influenza A (swine origin) were selected from highly conserved regions of the matrix (M), and the nucleoprotein (NP), respectively. Oligonucleotide primers and probes for characterization and differentiation of seasonal influenza A(H3) and A(H1)pdm09 viruses were selected from highly conserved regions of their respective HA genes. Detection of viral RNA not only aids in the diagnosis of illness caused by seasonal. newly emerging, and novel influenza viruses in patients with ILI, but also provides epidemiological and surveillance information on influenza and aids in the presumptive laboratory identification of specific novel influenza A viruses.

Here's a breakdown of the acceptance criteria and the study proving the device meets them, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria are implied through the performance metrics evaluated and compared to the predicate device and NGS as a gold standard. The core idea is that the modified assay should perform equivalently or better than the previous version, especially for strains with the 3' mutation.

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

• Sample Size (Clinical Evaluation):
  • Positive Specimen Panel: 60 influenza A(H3) specimens (30 with 3' mutation, 30 without 3' mutation).
  • Negative Specimen Panel: 60 negative specimens (from symptomatic patients known to be positive for influenza H1N1).
  • Total Clinical Test Set: 120 specimens (60 positive, 60 negative).
• Data Provenance: Retrospective study. Clinical specimens were collected from patients during previous influenza seasons in the United States.

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

Not applicable. The ground truth for the clinical test set was established using Next Generation Sequencing (NGS) and direct clinical specimen classification, not through expert consensus of visual or diagnostic interpretation.

4. Adjudication Method for the Test Set

Not applicable. The ground truth for the clinical test set was established via Next Generation Sequencing (NGS), which directly determines the genetic identity of the virus, rather than a consensus among human reviewers.

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 device is an in vitro diagnostic real-time RT-PCR diagnostic panel, not an AI-assisted diagnostic tool that would involve human readers interpreting AI output.

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

Yes, the performance evaluation in this submission is of the standalone device (algorithm only). The RT-PCR assay itself provides the result, without human interpretation of the assay's primary output (e.g., a visual scan of a reaction). The results are considered definitive from the machine output.

7. The Type of Ground Truth Used

• Analytical Performance: The ground truth for analytical sensitivity (LoD) and inclusivity studies was based on known, quantified viral stocks (EID50/mL or ID50/mL) of specific influenza strains.
• Clinical Performance: The ground truth for positive and negative clinical specimens was established using Next Generation Sequencing (NGS) as the comparator assay. This method directly confirms the identity and specific genetic characteristics (e.g., presence of 3' mutation) of the influenza virus in the samples.

8. The Sample Size for the Training Set

The document does not explicitly state a "training set" in the context of device development. This is a modification to an existing RT-PCR assay, and the "development" or "training" of such a device primarily involves bioinformatic analysis, primer/probe design adjustments, and analytical testing with known isolates. The "in-silico analysis" described (Process 1: assessment of primers against global H3N2 sequence information from GISAID EpiFlu database; Process 2: BLAST against NCBI nr/nt database) serves a similar function to a training set for algorithm-based devices by informing the optimal primer and probe sequences. No numerical sample size is provided for these bioinformatic databases.

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

As noted above, for an RT-PCR assay, the "training set" concept is different from an AI/ML context. The ground truth for informing the primer/probe design (which is effectively the "training" data for the assay's specificity and sensitivity for detecting target sequences) was established through:

• GISAID EpiFlu database: This database contains comprehensive, publicly shared influenza sequence information, used to assess potential primer and probe sets against known H3N2 sequences and calculate nucleotide mismatches. The sequences in this database are derived from laboratories globally undergoing influenza surveillance.
• NCBI BLAST+ against the nr/nt database: This is a vast database of non-redundant nucleotide sequences, against which primer sequences were compared to confirm inclusivity for H3 Influenza virus HA segments and exclusivity against non-target sequences.

This information is based on established genetic sequences, which serve as the fundamental "ground truth" for designing molecular diagnostic assays.

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The Lyra Influenza A+B Assay is a multiplex Real Time RT-PCR assay for the in vitro qualitative detection and differentiation of influenza A and influenza B viral RNA in nasal and nasopharyngeal swabs from patients with signs and symptoms of respiratory infection. This test is intended for use as an aid in the differential diagnosis of influenza A and influenza B viral infections in humans in conjunction with clinical and endemiological risk factors. The assay does not detect the presence of influenza C virus.

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

Performance characteristics for influenza A were established during the 2013 influenza seasons when influenza A/H3 and 2009 H1N1 influenza 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 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 assay can be performed using either the Life Technologies QuantStudio Dx, the Applied Biosystems 7500 Fast Dx or the Cepheid SmartCycler II.

The Lyra Influenza A+B Assay detects viral RNA that have been extracted from a patient sample using the NucliSENS easyMAG or EMAG automated extraction platform. A multiplex RT-PCR is carried out under optimized conditions in a single tube generating amplicons for each of the target viruses present in the sample. This reaction is performed utilizing either the Life Technologies QuantStudio™ Dx, the Applied Biosystems® 7500 Fast Dx, or the Cepheid® SmartCycler® II. Identification of influenza A occurs by the use of target specific primers and a fluorescent-labeled probe that hybridizes to a conserved influenza A sequence within the matrix protein gene. Identification of influenza B occurs by the use of target specific primers and fluorescent-labeled probes that will hybridize to a conserved influenza B sequence within the neuraminidase gene.

The provided text describes a 510(k) premarket notification for the Lyra Influenza A+B Assay. The notification primarily focuses on a modification to the device, specifically the inclusion of a new nucleic acid extraction platform (BioMerieux NucliSENS EMAG) while maintaining the original intended use and other core functionalities.

Here's an analysis of the acceptance criteria and study information based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

The document explicitly states that "All verification and validation activities were performed in accordance with relevant standards, established plans, protocols, and Design Control procedures. Testing verified all acceptance criteria were met." However, the specific quantitative acceptance criteria (e.g., sensitivity, specificity thresholds) are not detailed in the provided text. Similarly, the specific quantitative reported device performance metrics (e.g., exact sensitivity and specificity values) from the studies are not presented in the provided summary.

The summary only states: "Non-clinical and clinical verification activities conducted with the Lyra Influenza A+B Assay demonstrate that the modified device met predetermined acceptance criteria, supporting equivalency of the modified device to the cleared device."

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

The text mentions a "Clinical Equivalency Study" but does not provide details on the sample size used for its test set or the data provenance (e.g., country of origin, retrospective/prospective nature).

3. Number of Experts and Qualifications for Ground Truth

The document does not provide information on the number of experts used to establish ground truth for the test set or their qualifications.

4. Adjudication Method for the Test Set

The document does not provide information on the adjudication method used for the test set.

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

The text does not indicate that a multi-reader multi-case (MRMC) comparative effectiveness study was done. The focus is on the performance of the assay itself, not human reader improvement with/without AI assistance.

6. Standalone Performance Study

The studies mentioned ("Limit of Detection Equivalency Study" and "Clinical Equivalency Study") describe the performance of the device (algorithm/assay only), implying a standalone performance evaluation. However, the text does not explicitly use the term "standalone" or specify that it was "algorithm only without human-in-the-loop performance." Given that it's an RT-PCR assay, its performance by definition is standalone.

7. Type of Ground Truth Used

The text does not explicitly state the type of ground truth used for the clinical equivalency study. For diagnostic assays like this, ground truth is typically established through a combination of:

• Confirmatory laboratory methods (e.g., viral culture, another highly sensitive and specific PCR method, or sequencing as a gold standard).
• Clinical diagnosis by a physician.

However, this information is not provided.

8. Sample Size for the Training Set

The text does not provide information on a training set sample size. This is a modification to an existing assay, and the studies mentioned are verification/validation studies for the modification, not development studies for a new algorithm that would typically involve a separate training set.

9. How Ground Truth for the Training Set was Established

Since no training set information is provided, there is no information on how its ground truth was established.

Summary of Missing Information:

A significant amount of detail regarding the studies, particularly the quantitative acceptance criteria, reported performance, sample sizes, and ground truth methodologies, is not present in the provided FDA 510(k) summary letter. The letter serves as an approval notification and summary of the device's substantial equivalence, focusing on the change (new extraction platform) rather than a comprehensive, detailed clinical study report.

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The ID NOW™ Influenza A & B 2 assay performed on the ID NOW™ Instrument is a rapid molecular in vitro diagnostic test utilizing an isothermal nucleic acid amplification technology for the qualitative detection and discrimination of influenza A and B viral RNA in direct nasal or nasopharyngeal swabs and nasal or nasopharyngeal swabs eluted in viral transport media from patients with signs and symptoms of respiratory infection. It is intended for use as an aid in the differential diagnosis of influenza A and B viral infections in humans in conjunction with clinical and epidemiological risk factors. The assay is not intended to detect the presence of influenza C virus.

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

Performance characteristics for influenza A were established during the 2016-2017 influenza A/H3 and A/H1N1 pandemic 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 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.

ID NOW™ Strep A 2 is a rapid, instrument-based, molecular in vitro diagnostic test utilizing isothermal nucleic acid amplification technology for the qualitative detection of Streptococcus pyogenes, Group A Streptococcus bacterial nucleic acid in throat swab specimens obtained from patients with signs and symptoms of pharyngitis. It is intended to aid in the rapid diagnosis of Group A Streptococcus bacterial infections.

ID NOW™ Influenza A & B 2 is a rapid. instrument-based isothermal test for the qualitative detection and differentiation of influenza A and influenza B from nasal swab or nasopharyngeal swabs tested directly or after elution in viral transport media collected from patients presenting with signs and symptoms of respiratory infection.

ID NOW™ Strep A 2 is a rapid, instrument-based isothermal test for the qualitative detection of Group A Strep from throat swab specimens.

All ID NOW™ assays utilize isothermal nucleic acid amplification technology and are comprised of:

• Sample Receiver single use, disposable containing the elution buffer
• Test Base single use, disposable comprising two sealed reaction tubes, each containing a lyophilized pellet
• . Transfer Cartridge - single use, disposable for transfer of the eluted sample to the Test Base, and
• ID NOW™ Instrument repeat use reader

The reaction tubes in the ID NOW™ Influenza A & B 2 Test Base contain the reagents required for amplification of the target nucleic acid and an internal control. ID NOW™ Influenza A & B 2 utilizes a pair of templates (similar to primers) for the specific amplification of RNA from influenza A and B and a fluorescently labeled molecular beacon designed to specifically identify the amplified RNA targets.

The reaction tubes in the ID NOW™ Strep A 2 Test Base contain the reagents required for Group A Strep bacterial lysis and the subsequent amplification of the target nucleic acid and an internal control. ID NOW™ Strep A 2 utilizes a pair of templates (similar to primers) for the specific amplification of DNA from Group A Strep and a fluorescently labeled molecular beacon designed to specifically identify the amplified nucleic acid target.

All ID NOW™ assays are performed within the confinement of the Test Base, and no other part of the ID NOW™ Instrument has contact with the sample during the amplification process. This reduces the risk of instrument contamination and sample carry-over between measurements.

To perform the assay, the Sample Receiver and Test Base are inserted into the ID NOW™ Instrument and the elution buffer is automatically heated by the instrument. The sample is added to the Sample Receiver and transferred via the Transfer Cartridge to the Test Base, resuspending the lyophilized pellets contained within the Test Base and initiating bacterial lysis (for ID NOW™ Strep A 2) and target amplification. Heating, mixing and detection by fluorescence is provided by the instrument, with results automatically reported.

Results are displayed by the ID NOW™ Instrument and are also stored in an on-board archive and are assigned to a sample ID that has been entered into the ID NOW™ Instrument by the operator, and the date/time the test was performed. Data can be retrieved and downloaded by the operator at any time after testing. An external Universal Printer can be attached via USB to the ID NOW™ Instrument to print test results.

The document describes the modified software for the ID Now Instrument, encompassing ID NOW Influenza A & B 2 and ID NOW Strep A 2 assays. The modification specifically addresses false invalid results caused by baseline values being lower than allowed by the original algorithm, leading to incorrect identification as "Empty Tube Values." This is an algorithm update only, with no changes made to the chemistry of the assays.

Here's the breakdown of the acceptance criteria and the study proving the device meets them:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria for the modified software address the reduction of false invalid results. The document implies that the "performance" here relates to the analytical performance characteristics of the assays (e.g., sensitivity, specificity) remaining equivalent to the predicate devices despite the software change. While explicit numerical acceptance criteria for reduction in false invalid rate are not provided in this excerpt, the study aims to demonstrate that the new algorithm resolves the "false invalid" issue without compromising the core analytical performance.

For ID NOW™ Influenza A & B 2 (with software modification):

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CDC Human Influenza Real-Time RT-PCR Diagnostic Panel: Influenza A/B Typing Kit (VER 2)
The Influenza A/B Typing Kit contains reagents and controls of the CDC Human Influenza Virus Real-Time RT-PCR Diagnostic Panel and is intended for use in real-time RT-PCR (rRT-PCR) assays on an in vitro diagnostic real-time PCR instrument that has been FDA-cleared for use with this kit in conjunction with clinical and epidemiological information:

• · For qualitative detection of influenza virus type A or B viral RNA in upper respiratory tract clinical specimens (including nasopharyngeal swabs [NPS], nasal swabs [TS], nasal aspirates [NA], nasal washes [NW] and dual nasopharyngeal/throat swabs [NPS/TS]) and lower respiratory tract specimens (including bronchoalveolar lavage [BAL], bronchial wash [BW], tracheal aspirate [TA], sputum, and lung tissue) from human patients with signs and symptoms of respiratory infection and/or from viral culture.
• · To provide epidemiological information for surveillance of circulating influenza viruses.

CDC Human Influenza Real-Time RT-PCR Diagnostic Panel: Influenza A Subtyping Kit (VER 3)
The Influenza A Subtyping Kit contains reagents and controls of the CDC Human Influenza Virus Real-Time RT-PCR Diagnostic Panel and is intended for use in real-time RT-PCR (rRT-PCR) assays on an in vitro diagnostic real-time PCR instrument that has been FDA-cleared for use with this kit in conjunction with clinical and epidemiological information:

• · For determination of the subtype of seasonal human influenza A viruses as seasonal A(H3) and/or A(H1)pdm09 from viral RNA in upper respiratory tract clinical specimens (including nasopharyngeal swabs [NPS], nasal swabs [NS], throat swabs [TS], nasal aspirates [NA], nasal washes [NW] and dual nasopharyngeal/throat swabs [NPS/TS]) and lower respiratory tract specimens (including bronchoalveolar lavage [BAL], bronchial wash [BW], tracheal aspirate [TA], sputum, and lung tissue) from human patients with signs and symptoms of respiratory infection and/or from viral culture;
• · To provide epidemiological information for surveillance of circulating influenza viruses.

CDC Human Influenza Real-Time RT-PCR Diagnostic Panel: Influenza A/H5 Subtyping Kit (VER 4)
The Influenza A/H5 Subtyping Kit contains reagents and controls of the CDC Human Influenza Virus RT-PCR Diagnostic Panel and is intended for use in real-time RT-PCR (rRT-PCR) assays on an in vitro diagnostic real-time PCR instrument that has been FDA-cleared for use with this kit in conjunction with clinical and epidemiological information:

• · For the presumptive identification of virus in patients who may be infected with influenza A subtype A(H5) (Asian lineage) from viral RNA in human respiratory specimens and viral culture in conjunction with clinical and epidemiological risk factors;
• · To provide epidemiological information for surveillance of circulating influenza viruses.

The CDC Human Influenza Real-Time RT-PCR Diagnostic Panel is used in real-time RT-PCR (rRT-PCR) assays on an in vitro diagnostic real-time PCR system. The panel is configured in four separate kits. Each kit consists of oligonucleotide primers, fluorescently labeled hydrolysis probes, and controls which are used in rRT-PCR assays for the in vitro qualitative detection and characterization of influenza virus RNA in respiratory specimens from patients presenting with influenza-like illness (ILI). Oligonucleotide primers and probes for detection of influenza A, influenza B, and 2009 influenza A (swine origin) were selected from highly conserved regions of the matrix (M), non-structural (NS), and nucleoprotein (NP) genes, respectively. Oligonucleotide primers and probes for characterization and differentiation of influenza A(H3) and A(H1)pdm(9 viruses and genetic lineages of influenza B were selected from highly conserved regions of their HA genes. Oligonucleotide primers and probes to detect the human RNase P gene (RP) in control samples and clinical specimens is also included in the panel.

Here's a breakdown of the acceptance criteria and study information for the CDC Human Influenza Virus Real-time RT-PCR Diagnostic Panel, based on the provided text:

Acceptance Criteria and Reported Device Performance

The acceptance criteria are primarily related to analytical sensitivity (Limit of Detection - LOD) and inclusivity for various influenza A strains, and analytical specificity (cross-reactivity and exclusivity). The clinical performance evaluation also serves as a form of acceptance criteria for positive and negative agreement with previously characterized samples.

Study Details:

2. Sample sizes used for the test set and the data provenance (e.g., country of origin of the data, retrospective or prospective)

• LOD Equivalency & Confirmation:

  • Sample Size: Varies by virus strain and specific assay. For LOD equivalency, triplicate samples of serial dilutions were tested. For LOD confirmation, 20 individually extracted samples were tested for each target.
  • Data Provenance: Virus strains are identified by name and origin (e.g., A/Michigan/45/2015, A/Illinois/20/2018, A/Hong Kong/4801/2014, A/Abu Dhabi/240/2018, A/duck/Vietnam/NCVD-1544/2012, A/duck/Vietnam/NCVD-17A231/2016). Specific country of origin for all strains is not explicitly stated but implied from nomenclature.
  • Retrospective/Prospective: Experimental, controlled laboratory studies using characterized virus stocks.

• Inclusivity:

  • Sample Size: 10 influenza A(H1N1)pdm09 viruses and 24 influenza A viruses of various types/subtypes. Each virus sample was tested in triplicate.
  • Data Provenance: Virus strains represented temporal, geographic, and genetic diversity (e.g., A/Florida/81/2018, A/Alaska/35/2018, A/Switzerland/8060/2017).
  • Retrospective/Prospective: Experimental, controlled laboratory studies using characterized virus stocks.

• Analytical Specificity (Cross-Reactivity & Exclusivity):

  • Sample Size: Cross-reactivity: Various influenza viruses (e.g., A/Perth/16/2009, B/Maryland/15/2016) tested in triplicate. Exclusivity: 35 organisms (16 viruses, 18 bacteria, 1 yeast) tested.
  • Data Provenance: Organisms are identified by strain name.
  • Retrospective/Prospective: Experimental, controlled laboratory studies using characterized stocks of various organisms.

• Clinical Performance Evaluation:

  • Sample Size:
    • Modified InfA Assay: 62 positive (35 A(H1N1)pdm09, 27 A(H3N2)) and 50 negative residual human respiratory clinical specimens.
    • Modified pdmInfA and pdmH1 Assays: 35 positive (for A(H1N1)pdm09) and 50 negative residual human respiratory clinical specimens.
  • Data Provenance: Residual human respiratory clinical specimens collected from patients during previous influenza seasons in the United States (2011-12 and 2013-14).
  • Retrospective/Prospective: Retrospective.

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

The document does not specify the number or qualifications of experts used to establish ground truth. For the analytical studies (LOD, inclusivity, specificity), the ground truth is based on the known identity and titer of the cultured virus or bacterial/yeast strains. For the clinical performance evaluation, the ground truth for "positive" or "negative" status was established by prior testing (comparator) with the FDA-cleared CDC Human Influenza Real-Time RT-PCR Diagnostic Panel (K190302), which implicitly would have been validated using established laboratory methods or expert consensus in its own clearance process.

4. Adjudication method (e.g., 2+1, 3+1, none) for the test set

No explicit adjudication method (like 2+1 or 3+1 consensus) is described. The analytical studies often cite "number of positive replicates out of three total replicates tested," implying a direct comparison to the expected outcome from the known sample. For clinical studies, the comparator is the already FDA-cleared predicate device.

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 is not applicable. The device is an in vitro diagnostic real-time RT-PCR diagnostic panel, not an AI-assisted diagnostic tool that humans interpret. There are no "human readers" in the context of interpreting the device's output, nor is there a multi-reader multi-case study described.

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

Yes, the studies described are standalone because the device itself is a diagnostic assay (a collection of reagents and controls) that produces a result (detection/characterization of viral RNA) through a real-time RT-PCR instrument. While laboratory personnel operate the instrument and interpret the output, the core performance studies evaluate the assay's ability to detect the target without human intervention influencing the assay's chemical and enzymatic reactions. The term "algorithm" is not directly applicable in the same way as with AI software, but the assay's 'logic' for detection is intrinsic to its design.

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

• For Analytical Studies (LOD, Inclusivity, Specificity): The ground truth is based on known, characterized viral and microbial strains with established titers (e.g., TCID50/mL or EID50/mL) or concentrations (CFU/mL, ng/µL). This is a highly controlled laboratory ground truth.
• For Clinical Performance Evaluation: The ground truth was established by prior testing with the FDA-cleared CDC Human Influenza Real-Time RT-PCR Diagnostic Panel (K190302), acting as the comparator or reference method for the collected residual human respiratory clinical specimens.

8. The sample size for the training set

The document does not explicitly describe a separate "training set" in the context of machine learning or AI. This device is a RT-PCR based assay, and its development would typically involve empirical optimization and validation against a variety of known strains and clinical samples rather than a formal training set for an AI model.

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

As there is no explicit "training set" described for an AI model, this question is not directly applicable. For the development and optimization of the RT-PCR assays, ground truth for evaluating probe and primer design would have been established through a combination of sequencing data to identify conserved regions and target specificity, and testing against known, characterized viral isolates/strains to ensure desired reactivity.

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The FluChip-8G Influenza A+B Assay is a multiplex RT-PCR in vitro diagnostic test intended for the qualitative detection and differentiation of seasonal influenza A/H3N2, seasonal influenza A/H1N1pdm09, and "non-seasonal" influenza A subtypes other than seasonal H1N1pdm09 or H3N2. The assay is also intended for the qualitative detection and differentiation of the genetic lineage of human influenza B viruses as B/Victoria or B/Yamagata. The assay is designed for use on influenza nucleic acids isolated and purified from nasopharyngeal swab and nasal swab specimens from human patients with signs and symptoms of respiratory infection with clinical and epidemiological risk factors.

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The FluChip-8G Influenza A+B Assay is a multiplex RT-PCR in vitro diagnostic test for the qualitative detection and differentiation of influenza A and B viruses.

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

1. A table of acceptance criteria and the reported device performance

The provided text describes the indications for use of the FluChip-8G Influenza A+B Assay and mentions how performance characteristics were established. However, it does not explicitly state specific acceptance criteria (e.g., sensitivity, specificity thresholds) or a detailed table of reported device performance metrics against those criteria. Instead, it describes how performance was assessed.

For "non-seasonal" influenza A viruses, the document states:
"Due to low prevalence of 'non-seasonal' influenza A viruses, performance characteristics of the FluChip-8G Influenza A +B Assay for detecting 'non-seasonal' influenza A viruses and distinguishing 'non-seasonal' influenza A from seasonal influenza A H1N1pdm09 and H3N2 were assessed exclusively by conducting cross-validation on a total of 759 microarray images generated from bench testing contrived samples consisting of 352 unique 'non-seasonal' influenza A strains representing 62 subtypes, and by bench testing contrived samples and surrogate clinical specimens consisting of 133 unique non-seasonal influenza A strains representing 46 subtypes."

This indicates that evaluation was done, but specific performance metrics (e.g., sensitivity, specificity, accuracy) are not provided in this excerpt. The text implies the performance met the criteria for clearance, but the criteria themselves are not listed.

2. Sample size used for the test set and the data provenance (e.g., country of origin of the data, retrospective or prospective)

• Test set sample size:
  • For "non-seasonal" influenza A:
    • 759 microarray images from contrived samples (352 unique strains, 62 subtypes).
    • Contrived samples and surrogate clinical specimens (133 unique strains, 46 subtypes).
  • The document implies that seasonal influenza A/H3N2 and influenza B/Victoria data were used, but specific numbers for these are not provided.
• Data provenance: Not explicitly stated in terms of country of origin. The document mentions "the United States" in the context of predominant circulating strains ("seasonal influenza A/H3N2 was the predominant influenza A virus circulating in the United States" and "influenza B/Victoria was the predominant influenza B virus circulating in the United States"), suggesting the data is relevant to the US.
• Retrospective or prospective: The assessment for "non-seasonal" influenza A involved "bench testing contrived samples" and "surrogate clinical specimens," which sounds like a laboratory-controlled study rather than a prospective clinical trial on real patients. The nature of data used for seasonal influenza A and B is not specified.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g., radiologist with 10 years of experience)

This information is not provided in the given text.

4. Adjudication method (e.g., 2+1, 3+1, none) for the test set

This information is not provided in the given text.

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 is an in vitro diagnostic (IVD) device (a molecular assay) and not an AI-powered diagnostic imaging device or an AI assistant for human readers. Therefore, an MRMC comparative effectiveness study comparing human readers with and without AI assistance is not applicable and was not performed.

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

This is an in vitro diagnostic assay, which intrinsically operates in a "standalone" manner in terms of its analytical performance. While a human interprets the results generated by the assay, the "algorithm" (the RT-PCR and microarray detection process) performs its function independently of real-time human interpretation during the detection phase. The performance assessment described for "non-seasonal" influenza A via "cross-validation on a total of 759 microarray images generated from bench testing" and "bench testing contrived samples and surrogate clinical specimens" reflects the standalone performance of the assay.

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

The ground truth for the "non-seasonal" influenza A assessment was based on contrived samples and surrogate clinical specimens. This implies that the 'true' presence and subtype of the virus in these samples were known implicitly through their creation or characterization. For seasonal influenza A and B, the nature of the ground truth is not explicitly stated, but it would typically involve confirmed reference methods for viral identification and subtyping.

8. The sample size for the training set

The provided text describes performance assessment but does not mention a separate "training set" or its sample size. This assay is a molecular diagnostic test, not a machine learning algorithm in the typical sense that requires explicit training on a dataset to learn patterns. While internal development and optimization would have involved extensive testing, the public FDA document focuses on the validation of the final product.

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

As no specific "training set" is mentioned in the context of a machine learning algorithm, the establishment of ground truth for such a set is not applicable based on the provided text.

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The Influenza A/B Typing Kit contains reagents and controls of the CDC Human Influenza Virus Real-Time RT-PCR Diagnostic Panel and is intended for use in real-time RT-PCR (rRT-PCR) assays on an in vitro diagnostic real-time PCR instrument that has been FDA-cleared for use with this kit in conjunction with clinical and epidemiological information:
· For qualitative detection of influenza virus type A or B viral RNA in upper respiratory tract clinical specimens (including nasopharyngeal swabs [NPS], throat swabs [TS], nasal aspirates [NA], nasal washes [NW] and dual nasopharyngeal/throat swabs [NPS/TS]) and lower respiratory tract specimens (including bronchoalveolar lavage [BAL], bronchial wash [BW], tracheal aspirate [TA], sputum, and lung tissue) from human patients with signs and symptoms of respiratory infection and/or from viral culture;
· To provide epidemiologic information for surveillance of circulating influenza viruses.

The Influenza A Subtyping Kit contains reagents and controls of the CDC Human Influenza Virus Real-Time RT-PCR Diagnostic Panel and is intended for use in real-time RT-PCR (rRT-PCR) assays on an in vitro diagnostic real-time PCR instrument that has been FDA-cleared for use with this kit in conjunction with clinical and epidemiological information:
· For determination of the subtype of seasonal human influenza A viruses as seasonal A(H3), and/or A(H1)pdm09 from viral RNA in upper respiratory tract clinical specimens (including nasopharyngeal swabs [NS], throat swabs [TS], nasal aspirates [NA], nasal washes [NW] and dual nasopharyngeal/throat swabs [NPS/TS]) and lower respiratory tract specimens (including bronchoalveolar lavage [BAL], bronchial wash [BW], tracheal aspirate [TA], sputum, and lung tissue) from human patients with signs and symptoms of respiratory infection and or from viral culture;
· To provide epidemiologic information for surveillance of circulating influenza viruses.

The Influenza B Lineage Genotyping Kit contains reagents and controls of the CDC Human Influenza Virus Real-Time RT-PCR Diagnostic Panel and is intended for use in real-time RT-PCR ) assays on an in vitro diagnostic realtime PCR instrument that has been FDA-cleared for use with this kit in conjunction with clinical and epidemiological information:
· For the determination of the genetic lineage of human influenza B viruses as B/Victoria or B/Yamagata lineage from viral RNA in upper respiratory tract clinical specimens (including nasopharyngeal swabs [NS], throat swabs [TS], nasal aspirates [NA], nasal washes [NW] and dual nasopharyngeal/throat swabs [NPS/TS]) from human patients with signs and symptoms of respiratory infection and/or from viral culture;
· To provide epidemiologic information for surveillance of circulating influenza viruses.

The Influenza A/H5 Subtyping Kit contains reagents and controls of the CDC Human Influenza Virus RT-PCR Diagnostic Panel and is intended for use in real-time RT-PCR ) assays on an in vitro diagnostic real-time PCR instrument that has been FDA-cleared for use with this kit in conjunction with clinical and epidemiological information:
· For the presumptive identification of virus in patients who may be infected with influenza A subtype A(H5) (Asian lineage) from viral RNA in human respiratory specimens and viral culture in conjunction with clinical and epidemiological risk factors;
· To provide epidemiologic information for surveillance of circulating influenza viruses.

The CDC Human Influenza Real-Time RT-PCR Diagnostic Panel is used in real-time RT-PCR (rRT-PCR) assays on an in vitro diagnostic real-time PCR system. The panel is configured in four separate kits. Each kit consists of oligonucleotide primers, fluorescently labeled hydrolysis probes, and controls which are used in rRT-PCR assays for the in vitro qualitative detection and characterization of influenza virus RNA in respiratory specimens from patients presenting with influenza-like illness (ILI). Oligonucleotide primers and probes for detection of influenza A, influenza B, and 2009 influenza A (swine origin) were selected from highly conserved regions of the matrix (M), non-structural (NS), and nucleoprotein (NP) genes, respectively. Oligonucleotide primers and probes for characterization and differentiation of influenza A(H3) and A(H1)pdm(9 viruses and genetic lineages of influenza B were selected from highly conserved regions of their HA genes. Oligonucleotide primers and probes to detect the human RNase P gene (RP) in control samples and clinical specimens is also included in the panel.

Here's a breakdown of the acceptance criteria and study details based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance:

The document focuses on demonstrating substantial equivalence of the modified device (with new PCR instruments) to a predicate device. The key acceptance criteria are related to analytical sensitivity (Limit of Detection or LOD) and reproducibility, and clinical agreement.

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

• Analytical Sensitivity (LOD):

  • For each virus type and dilution: Triplicate samples were tested. The testing involved multiple influenza viruses (e.g., A/H3N2, A/H1N1pdm09, B/Victoria, B/Yamagata, A/H5N8) and two enzyme systems (SuperScript and qScript) across the original instrument and the two new instruments. It's difficult to give a single "sample size" number but it involved a substantial number of replicates across various conditions to establish LOD.
  • Data Provenance: The samples were "characterized influenza viruses of known egg infectious dose 50% titer," diluted in BPL-treated A549 cells in viral transport medium (VTM). This indicates laboratory-prepared, controlled samples.

• Analytical Precision (Reproducibility):

  • Sample Size: A blinded panel of 5 contrived samples (moderate positive A/H3N2, moderate positive B/Victoria, negative, low positive A/H3N2, low positive B/Victoria). Each sample was tested by two analysts at each of three sites, over five different days. This means for each contrived sample, there were $3 \text{ sites} \times 2 \text{ analysts} \times 5 \text{ days} = 30$ results. Across the 5 samples this totals $5 \text{ samples} \times 30 \text{ tests/sample} = 150$ tests for the QSDx and 150 for the QMDx.
  • Data Provenance: Contrived samples (BPL-treated A549 cells in VTM, spiked with BPL-treated influenza A(H3N2) or B/Victoria virus).

• Carryover and Cross-contamination:

  • Sample Size: An alternating pattern of high positive (HP) and negative (N) contrived samples. There were 5 high positive samples and 5 negative samples tested across 5 runs. The tables show 5 sets of HP samples and 5 sets of N samples for each assay (InfA, H5a, H5b, RP). For each assay, this means $5 \text{ HP samples} \times 5 \text{ runs} = 25$ tests and $5 \text{ N samples} \times 5 \text{ runs} = 25$ tests.
  • Data Provenance: Contrived samples (BPL-inactivated influenza A/gyrfalcon/41088-6/2014 (H5N8) in A549 cells).

• Clinical Performance Evaluation:

  • Sample Size: A total of 50 clinical specimens and 10 contrived samples with influenza A(H5) were used as positive samples (totaling 60 positive samples if the contrived A(H5) are counted separate from the 50 general clinical positives). And 50 negative specimens. So, a total of 100 retrospective samples (50 positive, 50 negative) were evaluated against the QSDx and QMDx independently.
  • Data Provenance:
    • Retrospective clinical specimens: Collected during the 2013-2014 influenza seasons. (Country of origin not specified, but given the CDC involvement, likely U.S.)
    • Contrived samples: The 10 A(H5) samples were "prepared with BPL-inactivated influenza A(H5) virus in a suspension of human A549 cells and virus transport medium."

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 mention the number of experts or their specific qualifications for establishing ground truth for the test set (clinical performance evaluation).

• For the analytical studies (LOD, reproducibility, carryover), the ground truth was established by the known characteristics of the prepared viral stocks and dilutions.
• For the clinical performance, the ground truth was established by the "previously determined" results using the FDA-cleared Applied Biosystems™ 7500 Fast Dx. This implies that the predicate device serves as the ground truth. It does not state that independent experts re-adjudicated these samples, but rather that the previously established results from a gold-standard method were used.

4. Adjudication Method for the Test Set:

No explicit adjudication method (e.g., 2+1, 3+1) is described for the clinical test set. The clinical samples were "previously determined to be positive using the Applied Biosystems™ 7500 Fast Dx." This implies the predicate device's results were considered the reference standard for comparison.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, What Was the Effect Size of How Much Human Readers Improve with AI vs Without AI Assistance:

This device is an in-vitro diagnostic (IVD) RT-PCR kit, not an AI-assisted diagnostic imaging device that involves human "readers" or AI assistance to humans. Therefore, an MRMC comparative effectiveness study involving human readers and AI assistance is not applicable and was not performed.

6. If a Standalone (i.e. algorithm only without human-in-the-loop performance) Was Done:

The entire study focuses on the standalone performance of the device (RT-PCR kit with its associated instruments). The device is an automated molecular diagnostic assay, not an AI algorithm. Its performance is evaluated objectively based on its ability to detect and characterize viral RNA. While human analysts perform the procedure and interpret the output, the core 'performance' refers to the analytical and clinical accuracy of the molecular reactions and instrument readings.

7. The Type of Ground Truth Used:

• Analytical Studies (LOD, Reproducibility, Carryover): The ground truth was based on known concentrations of characterized viral stocks (EID50/mL titer) and the specific composition of contrived samples (known to be positive or negative for certain influenza strains). This is a form of laboratory-established ground truth.
• Clinical Performance Evaluation: The ground truth for the clinical specimens was derived from results previously obtained using the FDA-cleared Applied Biosystems™ 7500 Fast Dx. This acts as a reference standard from a legally marketed and established device. For the A(H5) samples, it was based on the known composition of the contrived samples.

8. The Sample Size for the Training Set:

The document describes an evaluation study for substantial equivalence of a molecular diagnostic kit with new instrument platforms. It does not mention a "training set" in the context of machine learning. The "training" for such a molecular kit would involve the extensive R&D and optimization of the primer/probe sets and PCR conditions during the device's development, not a data-based training set for an AI algorithm.

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

As mentioned above, there is no explicit "training set" in the machine learning sense described in this document. The ground truth for the development and optimization of such a diagnostic panel typically involves:

• Known viral isolates/strains: Using cultured viruses with confirmed identity and titer.
• Sequencing data: To design highly specific and sensitive primers/probes targeting conserved regions of the viral genome.
• Clinical validation: Testing against a large panel of clinical samples, where the true infection status (ground truth) is established through gold-standard methods (e.g., viral culture, sequencing, or other highly sensitive and specific molecular tests) performed by expert laboratories.

The document briefly states: "Oligonucleotide primers and probes for detection of influenza A, influenza B, and 2009 influenza A (swine origin) were selected from highly conserved regions of the matrix (M), non-structural (NS), and nucleoprotein (NP) genes, respectively. Oligonucleotide primers and probes for characterization and differentiation of influenza A(H3) and A(H1)pdm(9 viruses and genetic lineages of influenza B were selected from highly conserved regions of their HA genes." This suggests an established ground truth based on genomic sequencing and bioinformatic analysis to design the assay.

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The ID NOW Influenza A & B 2 assay performed on the ID NOW Instrument is a rapid molecular in vitro diagnostic test utilizing an isothermal nucleic acid amplification technology for the qualitative detection and discrimination of influenza A and B viral RNA in direct nasal or nasopharyngeal swabs and nasal or nasopharyngeal swabs eluted in viral transport media from patients with signs and symptoms of respiratory infection. It is intended for use as an aid in the differential diagnosis of influenza A and B viral infections in conjunction with clinical and epidemiological risk factors. The assay is not intended to detect the presence of influenza C virus.

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

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.

ID NOW Influenza A & B 2 is a rapid, instrument-based isothermal test for the qualitative detection and differentiation of influenza A and influenza B from nasal or nasopharyngeal swabs tested directly or after elution in viral transport media collected from patients presenting with signs and symptoms of respiratory infection.

The ID NOW Influenza A & B 2 system utilizes isothermal nucleic acid amplification technology and is comprised of:

• Sample Receiver single use, disposable containing the elution buffer
• Test Base - single use, disposable comprising two sealed reaction tubes, each containing a lyophilized pellet
• Transfer Cartridge single use, disposable for transfer of the eluted sample to the Test Base, and
• ID NOW Instrument repeat use reader.

The reaction tubes in the Test Base contain the reagents required for amplification of the target nucleic acid and an internal control. ID NOW Influenza A & B 2 utilizes a pair of templates (similar to primers) for the specific amplification of RNA from influenza A and B and a fluorescently labeled molecular beacon designed to specifically identify the amplified RNA targets.

ID NOW Influenza A & B 2 is performed within the confinement of the Test Base, and no other part of the ID NOW Instrument has contact with the sample during the amplification process. This reduces the risk of instrument contamination and sample carry-over between measurements.

To perform the assay, the Sample Receiver and Test Base are inserted into the ID NOW Instrument and the elution buffer is automatically heated by the instrument. The sample is added to the Sample Receiver and transferred via the Transfer Cartridge to the Test Base, resuspending the lyophilized pellets contained within the Test Base and initiating target amplification. Heating, mixing and detection by fluorescence is provided by the instrument, with results automatically reported.

Results are displayed by the ID NOW Instrument and are also stored in an on-board archive and are assigned to a sample ID that has been entered into the ID NOW Instrument by the operator, and the date/time the test was performed. Data can be retrieved and downloaded by the operator at any time after testing. An external Alere™ Universal Printer can be attached via USB to the ID NOW Instrument to print test results.

The provided FDA 510(k) clearance letter and summary for the "ID NOW Influenza A & B 2" device (K190204) primarily focus on a labeling modification to expand specimen transport and storage instructions. It explicitly states: "This is a labeling update only, there have been no changes to the Intended Use or fundamental scientific technology of the ID NOW Influenza A & B 2 assay."

Therefore, this document does not contain the details of an acceptance criteria study or the detailed performance data as would be found in an original 510(k) submission for the device itself. Instead, it refers to the predicate device (K173932), implying that the performance criteria and supporting studies were established and documented during the clearance of that predicate device.

Based on the provided text, I cannot describe a new acceptance criteria study or new performance data for K190204, as this submission explicitly states none were performed for the device's fundamental function.

However, I can extract information related to the device itself and its general intended use, and explain why the requested information isn't present in this specific document.

Analysis of Provided Document's Relevance to Acceptance Criteria and Study Details:

The current document (K190204) is a "Special 510(k)" submission for a modification to an already cleared device. This type of submission does not typically include a full re-evaluation of the device's fundamental performance unless the modification directly impacts its safety or effectiveness in a new way. In this case, the modification is explicitly stated as only a labeling change related to specimen storage.

Therefore, the document does not provide the following information directly:

• A table of acceptance criteria and reported device performance for K190204 itself, because no new performance study was conducted for this specific submission. The performance data would have been part of the original submission for K173932.
• Sample sizes used for a test set for this submission.
• Protocols for establishing ground truth (experts, adjudication, etc.) for a substantial performance study.
• Details of MRMC studies or effect sizes.
• Standalone performance data (as this is a labeling update, not a new device or performance claim).
• Details on training set sample size or ground truth establishment for a new AI/algorithm (as this is a molecular diagnostic test, not an AI-based imaging diagnostic).

Information that can be inferred or directly stated from the document:

• Device Type: Rapid molecular in vitro diagnostic test. This is important because the requested ground truth types (pathology, expert consensus) are more relevant to imaging AI; for molecular diagnostics, ground truth is typically established by definitive laboratory methods (e.g., PCR reference methods, viral culture).
• Technology: Isothermal nucleic acid amplification technology.
• Targets: Influenza A and B viral RNA.
• Sample Type: Direct nasal or nasopharyngeal swabs, and nasal/nasopharyngeal swabs eluted in viral transport media.
• Result Type: Qualitative (detection/discrimination).
• Internal Control: Yes.
• Result Interpretation: Automated.
• Predicate Device: K173932 (ID NOW Influenza A & B 2). This implies that the validation and acceptance criteria for performance were established during the clearance of K173932.

Hypothetical Example of how the requested information would be presented for a diagnostic device, if this document were an original submission with performance data:

If this were an original 510(k) submission for a new diagnostic device requiring clinical validation, the document would typically include sections detailing:

1. Acceptance Criteria and Performance:

   Performance Metric	Acceptance Criteria (e.g., % Concordance)	Reported Performance (e.g., % Concordance, Sensitivity, Specificity)
   Overall Agreement	≥ 95%	97.2%
   Positive Agreement (PPA) for Flu A	≥ 90% (vs. Comparator X)	93.5% (vs. RT-qPCR)
   Negative Agreement (NPA) for Flu A	≥ 95% (vs. Comparator X)	98.1% (vs. RT-qPCR)
   Positive Agreement (PPA) for Flu B	≥ 90% (vs. Comparator X)	92.8% (vs. RT-qPCR)
   Negative Agreement (NPA) for Flu B	≥ 95% (vs. Comparator X)	97.5% (vs. RT-qPCR)
   Limit of Detection	Defined concentration (e.g., X copies/mL)	Y copies/mL
   Cross-Reactivity	No cross-reactivity with specified organisms	No cross-reactivity with A, B, C...
   Note: The specific metrics and thresholds would depend on the device type and intended use.

2. Sample Sizes and Data Provenance (for test set, if applicable to a clinical study):

   • Sample Size: e.g., 500 clinical samples (250 positive, 250 negative)
   • Data Provenance: Prospective collection from multiple clinical sites in the USA. Samples collected from patients presenting with signs/symptoms of respiratory infection during influenza season.

3. Ground Truth Establishment (for test set, if applicable):

   • Number of Experts/Reference Methods: Ground truth established by a highly sensitive and specific reference method, such as real-time Reverse Transcription Polymerase Chain Reaction (RT-qPCR) with validated primers and probes, performed by a CLIA-certified laboratory.
   • Qualifications of Experts (if human review was part of GT): Not directly applicable for a molecular test's primary ground truth, but if comparator methods involved experts, their qualifications (e.g., board-certified clinical microbiologists) would be relevant.

4. Adjudication Method:

   • Not applicable as primary ground truth is objective molecular test; if discordant results between the device and the reference method were analyzed, they might be adjudicated by re-testing or sequencing.

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

   • Not applicable for a molecular diagnostic device of this type, as it does not involve human readers interpreting images or data for diagnosis. This type of study is common for AI-powered imaging devices.

6. Standalone Performance:

   • The "reported performance" table above is the standalone performance for a fully automated molecular diagnostic device like this. There is no "human-in-the-loop" for result interpretation.

7. Type of Ground Truth Used:

   • Reference molecular testing: Typically RT-qPCR or similar highly sensitive and specific molecular assays, often using independent, validated methods. In some cases, viral culture could also be used as a reference. Clinical outcomes data might be used in broader epidemiological studies but not typically as the direct ground truth for analytical device performance.

8. Training Set Sample Size:

   • For a molecular diagnostic test, "training set" doesn't apply in the same way as for AI. Instead, there would be extensive analytical validation data (e.g., inclusivity, exclusivity, LOD, linearity, precision) generated by testing panels of characterized specimens and analytical dilutions. The "sample size" here would refer to the number of characterized panels and replicates used for these studies.

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

   • Again, for a molecular diagnostic, this refers to how the analytical samples were characterized. This is typically done through nucleic acid sequencing, quantitative PCR, or other highly accurate methods to determine the presence, type, and concentration of the target analyte in analytical samples. Clinical samples used in analytical studies would be highly characterized using established reference methods.

In summary, while the provided document gives valuable information about the device's intended use and the specific change for this 510(k), it does not contain the detailed performance study information that would have been part of the original 510(k) submission (K173932) for the ID NOW Influenza A & B 2 device.

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The Influenza B Lineage Genotyping Kit contains reagents and controls of the CDC Human Influenza Virus Real-Time RT-PCR Diagnostic Panel and is intended for use in real-time RT-PCR (rRT-PCR) assays on an Applied Biosystems (ABI) 7500 Fast Dx Real-Time PCR instrument in conjunction with clinical and epidemiological information:

For the determination of the genetic lineage of human influenza B viruses as B/Victoria or B/Yamagata lineage from · viral RNA in upper respiratory tract clinical specimens (including nasopharyngeal swabs [NS], throat swabs [TS], nasal aspirates [NA], nasal washes [NW] and dual nasopharyngeal/throat swabs [NPS/TS]) from human patients with signs and symptoms of respiratory infection and/or from viral culture;

· To provide epidemiologic information for surveillance of circulating influenza viruses.

Performance characteristics for influenza B lineage genotyping were established during a season when influenza B/ Victoria and B/Yamagata lineages were in circulation.

Negative results do not preclude influenza virus infection and should not be used as the sole basis for treatment or other patient management decisions. Conversely, positive results do not rule out bacterial infection with other viruses. The agent detected may not be the definite cause of disease.

All users, and any person reporting results from use of this device should be trained to perform and interpret the results from this procedure by a competent instructor prior to use. CDC Influenza Division will limit the distribution of this device to only those users who have successfully completed a training course provided by CDC instructors or designees.

The CDC Human Influenza Real-Time RT-PCR Diagnostic Panel is used in real-time RT-PCR (rRT-PCR) assays on the Applied Biosystems® (ABI) 7500 Fast Dx Real-time PCR system. The panel is configured in four separate kits. Each kit consists of oligonucleotide primers. fluorescently labeled hydrolysis probes, and controls which are used in rRT-PCR assays for the in vitro qualitative detection and characterization of influenza virus RNA in respiratory specimens from patients presenting with influenza-like illness (ILI). Oligonucleotide primers and probes included in the Influenza B Lineage Genotyping Kit for detection of influenza B and the two major genetic lineages of influenza B were selected from highly conserved regions of the non-structural (NS) and HA genes, respectively. Oligonucleotide primers and probes to detect the human RNase P gene (RP) in control samples and clinical specimens are also included in the kit.

Here's a summary of the acceptance criteria and study details for the CDC Human Influenza Virus Real-Time RT-PCR Diagnostic Panel: Influenza B Lineage Genotyping Kit, based on the provided document:

This document describes a 510(k) premarket notification for modifications to an existing influenza B lineage genotyping kit (K172091). The changes primarily address recent evolutionary changes in circulating influenza B viruses that could impact the reactivity of the current kit, and the evaluation of an alternative fluorescent hydrolysis probe quencher chemistry (ZEN™). The study aims to demonstrate that the modified device remains substantially equivalent to the predicate device.

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria are generally demonstrated through 100% agreement or high percentage sensitivity/specificity with a clear lower bound for the 95% Confidence Interval (CI).

Influenza B Lineage Genotyping Assay (VER 1.1 and VER 2 VIC & YAM assays): All assays demonstrated similar reactivity with apparent LOD endpoints within one 5-fold dilution of each other for various B/Victoria and B/Yamagata strains across both enzyme systems (Invitrogen Superscript™ and Quanta qScript™). For example, LOD for B/Maryland/15/2016 (VER 1.1 & VER 2) was 10^1.7 EID50/mL for both enzymes. |
| Analytical Sensitivity (LOD Confirmation) | Lowest virus concentration where InfB and VIC or InfB and YAM primer and probe sets demonstrated ≥ 95% detection. | Demonstrated LODs for B/Maryland/15/2016 (Victoria) were 10^1.7 EID50/mL for both VER 1.1 and VER 2 with both enzyme systems. Demonstrated LODs for B/Texas/81/2016 (Yamagata) were 10^2.2 EID50/mL (VER 1.1 & VER 2 with Invitrogen) and 10^1.5 EID50/mL (VER 1.1 & VER 2 with Quanta). |
| Analytical Sensitivity (Inclusivity) | 100% positivity (3 out of 3 replicates) for the tested strains at or near the established LOD. | B/Victoria (VER 1.1 & VER 2): All 10 tested B/Victoria strains showed 3/3 positive replicates (100% inclusivity) at or near their LOD for both VER 1.1 and VER 2, across both enzyme systems.
B/Yamagata (VER 1.1 & VER 2): All 10 tested B/Yamagata strains showed 3/3 positive replicates (100% inclusivity) at or near their LOD for both VER 1.1 and VER 2, across both enzyme systems. |
| Analytical Specificity (Cross-Reactivity) | No cross-reactivity detected with the opposite influenza B lineage. | No cross-reactivity was detected with either VER 1.1 or VER 2 VIC and YAM primer/probe sets when tested against 10 high-titer B/Yamagata lineage viruses (for VIC assays) and 10 high-titer B/Victoria lineage viruses (for YAM assays), across both enzyme systems. (Results consistently showed '-') |
| Analytical Specificity (Exclusivity with Influenza A Viruses) | No cross-reactivity detected with various influenza A viruses. | No cross-reactivity was detected with either VER 1.1 or VER 2 VIC and YAM assays when tested against 8 high-titer Influenza A viruses of various human and animal subtypes, across both enzyme systems. (Results consistently showed '-') |
| Analytical Specificity (Exclusivity with Non-Influenza Respiratory Pathogens) | No cross-reactivity detected with common non-influenza respiratory pathogens or flora. | No cross-reactivity was detected with VER 2 VIC and YAM assays when tested against 36 organisms (16 viruses, 19 bacteria, and 1 yeast) at high titers, across both enzyme systems. (Results consistently showed '-') |
| Clinical Performance (Retrospective InfB Assay) | 100% positive and negative agreement with the cleared oligonucleotide probe (BHQ quencher). | 100.0% Positive Agreement (95% CI: 88.7-100.0) for 30/30 positive samples. 100.0% Negative Agreement (95% CI: 92.9-100.0) for 50/50 negative samples. (Both enzyme systems showed identical results). |
| Clinical Performance (VER 2 B/Victoria Prospective Study) | High sensitivity and specificity, typically aiming for >90% sensitivity and >95% specificity with a tight 95% CI. | Sensitivity: 100.0% (5/5 positives) (95% CI: 56.6 – 100.0).
Specificity: 100.0% (574/574 negatives) (95% CI: 99.3 – 100.0). (Note: Low number of positives impacts CI width for sensitivity). |
| Clinical Performance (VER 2 B/Yamagata Prospective Study) | High sensitivity and specificity, typically aiming for >90% sensitivity and >95% specificity with a tight 95% CI. | Sensitivity: 100.0% (38/38 positives) (95% CI: 90.8 – 100.0).
Specificity: 99.8% (540/541 negatives) (95% CI: 99.0 – 100.0). |
| Clinical Performance (Retrospective VER 1.1 & VER 2 VIC & YAM assays) | 100% positive and negative agreement with the FDA-cleared Influenza B Lineage Genotyping Kit. | VIC VER 1.1: 100.0% Positive Agreement (30/30) (95% CI: 88.7 - 100.0); 100.0% Negative Agreement (157/157) (95% CI: 97.6 - 100.0).
YAM VER 1.1: 100.0% Positive Agreement (96/96) (95% CI: 96.2 - 100.0); 100.0% Negative Agreement (91/91) (95% CI: 96.0 - 100.0).
VIC VER 2: 100.0% Positive Agreement (30/30) (95% CI: 88.7 - 100.0); 100.0% Negative Agreement (157/157) (95% CI: 97.6 - 100.0).
YAM VER 2: 100.0% Positive Agreement (96/96) (95% CI: 96.2 - 100.0); 100.0% Negative Agreement (91/91) (95% CI: 96.0 - 100.0). |

2. Sample Size for the Test Set and Data Provenance

Test Set Sample Sizes:

• Analytical Sensitivity (LOD Equivalency & Inclusivity): Varied. Typically, 3 replicates per dilution/strain. For LOD confirmation, 20 extraction replicates per dilution.
• Analytical Specificity (Cross-Reactivity & Exclusivity): For cross-reactivity, 10 B/Yamagata strains for VIC assays and 10 B/Victoria strains for YAM assays. For exclusivity with Influenza A, 8 Influenza A strains. For exclusivity with non-influenza pathogens, 36 organisms (16 viruses, 19 bacteria, 1 yeast). All tested with both enzyme systems.
• Clinical Performance (InfB Assay Retrospective): 30 positive and 50 negative upper respiratory tract clinical samples.
• Clinical Performance (VER 2 Prospective Study):
  • Total collected: 592 samples.
  • Analyzed: 579 upper respiratory tract clinical specimens.
  • B/Victoria: 5 positive, 574 negative.
  • B/Yamagata: 38 positive, 541 negative.
• Clinical Performance (VER 1.1 & VER 2 Retrospective Study):
  • 126 specimens positive for either influenza B/Victoria or B/Yamagata viruses.
  • 61 specimens negative for influenza B viruses.
  • (An additional 4 lung tissue specimens were tested for informational purposes but not included in performance calculations).

Data Provenance:

• Analytical studies: Laboratory-characterized virus stocks and reference strains (e.g., CDC repositories, ATCC).
• Clinical Performance (InfB Assay Retrospective): Retrospective clinical samples collected during the 2011-2012 influenza season.
• Clinical Performance (VER 2 Prospective Study): Prospective clinical investigation conducted at 3 U.S. public health laboratories using upper respiratory tract specimens collected during the 2016-2017 influenza season.
• Clinical Performance (VER 1.1 & VER 2 Retrospective Study): Retrospective upper respiratory tract clinical samples collected during the 2017 and 2017-2018 influenza seasons.

Country of Origin: Primarily the United States (CDC, U.S. public health laboratories) with some virus strains noted as originating from various international locations (e.g., Hong Kong, Bolivia, Laos, Michigan, etc.) for inclusivity and exclusivity testing, reflecting global diversity.

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

The ground truth for the test sets (both analytical and clinical) appears to be established by molecular diagnostic methods using an FDA-cleared predicate device, the CDC Human Influenza Virus Real-Time RT-PCR Diagnostic Panel: Influenza B Lineage Genotyping Kit (K172091), and/or by using well-characterized virus stocks with known titers (EID50/mL or TCID50/mL).

For clinical samples, they were "previously determined to be positive or negative for influenza B virus" or "determined to be positive for influenza B/Victoria or B/Yamagata viruses using the FDA-cleared Influenza B Lineage Genotyping Kit."

The document does not explicitly mention the use of a specific "number of experts" (e.g., clinicians, virologists, or laboratory professionals) for establishing the individual patient-level clinical ground truth for the test sets in the same way one might describe image interpretation by radiologists. Instead, the ground truth is primarily based on the results of the already FDA-cleared predicate diagnostic test or characterized reference materials. The "competent instructor" trained individuals (users, analysts, and those reporting results) on how to perform and interpret the device results.

4. Adjudication Method for the Test Set

The document does not describe an adjudication method for conflicting results in the test set, such as a 2+1 or 3+1 system. This is typical for molecular diagnostic studies where the comparison is generally made against a well-established reference method (the predicate device or characterized stocks). Any discrepancies would likely be investigated to determine the cause (e.g., retesting, review of sample integrity, or confirmation by alternative gold standard) rather than being resolved by expert consensus in a traditional adjudication panel format. For example, in the LOD studies, "3 out of 3 replicates" or "≥ 95% detection" criteria are used, indicating a reliance on consistent assay performance rather than expert adjudication.

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

No, a multi-reader multi-case (MRMC) comparative effectiveness study was not explicitly described. MRMC studies are typically performed for imaging devices or other diagnostics where human interpretation is a key component and the effect of AI assistance on human performance is being evaluated. This submission is for a molecular diagnostic (RT-PCR kit) where the output is a quantitative measurement (Ct values) and qualitative result (positive/negative, lineage determination) interpreted directly by the instrument software or a trained individual following predefined rules, not a subjective interpretation by multiple human readers.

Therefore, there is no mention of an effect size of how much human readers improve with AI vs. without AI assistance.

6. Standalone (Algorithm Only) Performance

Yes, the studies presented primarily represent standalone performance of the device (or its modified components). The analytical performance evaluations (sensitivity, inclusivity, specificity, exclusivity) directly assess the algorithm's (reagent kit's) ability to detect and differentiate influenza B lineages from viral RNA. The clinical performance studies compare the results of the investigational device directly against the FDA-cleared predicate device on clinical samples. While human technicians perform the laboratory procedures, the "algorithm" here refers to the specific RT-PCR assay chemistry, probes, and primer sets that yield a result, which is then interpreted according to established cut-offs/rules, not an AI algorithm that assists human interpretation.

7. Type of Ground Truth Used

The ground truth used for the studies is a combination of:

• Reference standard/Predicate device: For clinical samples, the ground truth was largely established by the "FDA-cleared CDC Human Influenza Virus Real-Time RT-PCR Diagnostic Panel: Influenza B Lineage Genotyping Kit."
• Characterized virus stocks: For analytical studies (LOD, inclusivity, cross-reactivity, exclusivity), the ground truth was established using well-characterized influenza virus stocks and other respiratory pathogens with known strain designations, subtypes, and titers (EID50/mL, TCID50/mL, CFU/mL, or ng/µL). This implies a high level of confidence in the identity and concentration of the biological material.

8. Sample Size for the Training Set

The document does not explicitly state a sample size for a "training set" in the context of an algorithm's development. This is because the device described is a molecular diagnostic kit (RT-PCR) with specific primers and probes designed based on biological knowledge of viral sequences, rather than a machine learning or artificial intelligence algorithm that requires a distinct training phase with labeled data.

The "modifications" were "primarily to address recent evolutionary changes in circulating influenza B viruses that may impact the reactivity of the current Influenza B Lineage Genotyping Kit. Two design approaches were evaluated that address specific genetic mutations in the targeted hemagglutinin (HA) gene..." This indicates a design process driven by biological knowledge and engineering based on viral genetics, not data-driven machine learning training.

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

Since there's no explicitly defined "training set" for an AI algorithm in the provided text, the concept of establishing ground truth for it doesn't directly apply. The design of the new VER 1.1 and VER 2 assays was based on scientific understanding of circulating influenza B virus evolutionary changes and specific genetic mutations in the HA gene. This informed the selection of the oligonucleotide primers and probes. The efficacy of these new designs was then evaluated using the analytical and clinical studies described in the rest of the document, where the ground truth was established as detailed in point 7.

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