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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):

For ID NOW™ Strep A 2 (with software modification):

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

This document describes a Special 510(k) submission which is typically used for well-defined modifications to a legally marketed device where the modification does not affect the fundamental scientific technology of the device or its intended use. In such cases, extensive new clinical studies with large, prospectively collected sample sets might not be required if analytical performance remains equivalent and the specific issue (false invalids) is addressed.

The provided excerpt does not specify the sample size used for the test set or the data provenance (e.g., country of origin, retrospective/prospective). For a software modification intended to fix a specific issue like "false invalid results due to baseline values," the testing typically involves:

• Retrospective analysis of stored clinical samples that previously yielded false invalid results.
• Prospective testing of both contrived and potentially clinical samples designed to challenge the new algorithm's ability to correctly classify results, especially those with low baseline values.
• Analytical studies (e.g., limit of detection, inclusivity/exclusivity) to confirm that the change did not negatively impact the assay's performance characteristics.

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

Given this is a molecular diagnostic test for direct pathogen detection, the ground truth for such devices is typically established through definitive laboratory methods (e.g., highly sensitive PCR, culture, sequencing) rather than expert human interpretation of images or other subjective data. Therefore, the concept of "experts" in the sense of radiologists providing ground truth is not applicable here.

4. Adjudication Method for the Test Set

Not applicable in the context of a molecular diagnostic assay where ground truth is established by objective laboratory methods.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done, and effect size of how much human readers improve with AI vs without AI assistance

Not applicable. This device is a molecular diagnostic assay, not an AI-assisted diagnostic imaging device that involves human reader interpretation.

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

Yes, in principle, the "performance" of the algorithm is assessed in a standalone manner. The device outputs a qualitative result ("Positive", "Negative", or "Invalid"). The study demonstrating the effectiveness of the software modification would specifically evaluate the algorithm's ability to correctly interpret the reaction (i.e., generate "Positive" or "Negative" results) and to correctly resolve cases that were previously generating "false invalid" results. There is no human-in-the-loop during the interpretation phase of these tests.

7. The Type of Ground Truth Used

The ground truth for molecular diagnostic tests like ID NOW Influenza A & B 2 and ID NOW Strep A 2 is generally established using reference laboratory methods that reliably detect the target nucleic acid or pathogen. This could include:

• Culture: For bacterial targets like Streptococcus pyogenes.
• PCR (Polymerase Chain Reaction) or RT-PCR: Highly sensitive and specific molecular methods, often considered the gold standard for detecting viral or bacterial nucleic acids.
• Sequencing: To confirm the presence and identity of specific pathogen strains.

The purpose of the software modification was to improve the algorithm's interpretation of internal controls and baseline signals to prevent erroneous invalid results, while ensuring the accuracy (sensitivity and specificity) of positive/negative calls remained consistent with the gold standard.

8. The Sample Size for the Training Set

The document does not specify the sample size for the training set. For a software modification to an existing algorithm like this, the "training" (or development and refinement) might involve:

• Analyzing a dataset of historical internal control and baseline signal data, especially from cases that yielded false invalid results.
• Developing and testing new thresholds or algorithms on this historical data.

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

For the purpose of training an algorithm to address "false invalid" results, the "ground truth" would be established by:

• Investigating the source of the invalid signal: This might involve re-running the samples on a reference method to determine the true positive/negative status and then analyzing the raw signal data from the initial ID NOW test to understand why the invalid result occurred.
• Characterizing "Empty Tube Values": Understanding the expected signal profiles when no reaction occurs or when the internal controls fail, versus when the assay is truly inhibited, or the baseline is genuinely low but still allows for a valid result. The ground truth for these investigations would be meticulously verified analytical data and, if applicable, the true clinical status (positive/negative by a gold standard method).

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