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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 season when 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 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.

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.

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 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 provided text describes a 510(k) submission for the ID NOW™ Influenza A & B 2 assay, specifically focusing on a software modification to mitigate potential false positive Influenza B test results during sequential workflow testing. The submission is a "Special 510(k)," indicating that the changes are minor and do not significantly alter the device's fundamental technology or safety/effectiveness.

The document emphasizes the equivalence to a legally marketed predicate device (ID NOW Influenza A & B 2, K220801). Therefore, the study presented here is primarily a comparative study to demonstrate that the modified device performs equivalently to the predicate, rather than establishing de novo performance characteristics against a clinical ground truth for a novel device.

Here's an analysis of the provided information, framed by your request for acceptance criteria and study details:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria for this Special 510(k) are implicitly tied to demonstrating non-inferiority or equivalence of the modified device's performance to the predicate device, particularly concerning the reduction of false positives for Influenza B. The document states:

• "A modification of the ID NOW Influenza A & B 2 algorithm was made, as a preventive measure, to mitigate the potential occurrence of false positive Influenza B test results during sequential workflow testing."
• "ID NOW Influenza A & B 2 incorporating the software modification was compared to the legally marketed predicate device, the 510(k) cleared ID NOW Influenza A & B 2."

While the document states the purpose and the comparison, it does not explicitly list quantitative acceptance criteria (e.g., a specific percentage reduction in false positives, or a non-inferiority margin for sensitivity/specificity) or the reported device performance in a table format as you requested. The provided text is a summary letter and general description, not a detailed study report. For a device like this, the performance data (sensitivity, specificity, positive predictive value, negative predictive value) for both the modified and predicate devices would typically be presented in the detailed 510(k) submission, but this information is not included in the provided excerpt.

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

The provided text does not explicitly state the sample size used for the test set. It mentions the study compares the modified device to the predicate, implying a test set was used for this comparison.

Regarding data provenance: The document does not specify the country of origin of the data or whether the data was retrospective or prospective. These details would be crucial for a full understanding of the study's design.

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

For a molecular diagnostic test like ID NOW Influenza A & B 2, the "ground truth" is typically established by a highly sensitive and specific reference method, such as RT-PCR (Reverse Transcription Polymerase Chain Reaction), which is considered the gold standard for viral detection. The document does not mention the use of human experts (e.g., radiologists) to establish ground truth because this is a laboratory diagnostic assay, not an imaging device. Therefore, no information is provided on expert qualifications or the number of experts.

4. Adjudication Method for the Test Set

Since the ground truth for molecular diagnostics is typically established by a reference laboratory method (e.g., RT-PCR), an "adjudication method" involving human readers (like 2+1 or 3+1 for imaging studies) is not applicable in this context and is therefore not mentioned.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was Done

No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not applicable and therefore not done. MRMC studies are typically used for evaluating diagnostic imaging systems where human interpretation plays a critical role, and the impact of AI assistance on human reader performance is being assessed. The ID NOW Influenza A & B 2 is an automated molecular diagnostic test; human "readers" do not interpret results in the same way as in imaging.

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

Yes, the very nature of this device (an automated molecular diagnostic test) means that the performance is standalone (algorithm only without human-in-the-loop performance). The ID NOW Instrument performs the test, processes the sample, and reports results automatically. The software modification described directly impacts this automated process. The comparison to the predicate device would inherently evaluate the standalone performance of the modified algorithm against the predicate algorithm.

7. The Type of Ground Truth Used

As mentioned in point 3, the ground truth for molecular diagnostic tests like this is almost universally established by a highly sensitive and specific reference laboratory method, typically RT-PCR. While the document does not explicitly state "RT-PCR was used as ground truth," this is the industry standard for validating such devices. "Expert consensus," "pathology," or "outcomes data" are generally not the primary ground truth methods for direct viral detection assays.

8. The Sample Size for the Training Set

The document does not provide any information regarding a training set sample size. This is a software modification to an existing, cleared device, implying the original device would have undergone substantial training and validation. For a Special 510(k) focusing on a specific bug fix (false positives in sequential workflow), the emphasis is on a targeted verification and validation of the change, rather than retraining a comprehensive model. If a machine learning model were involved, reporting training set size would be crucial, but the description here suggests a more rule-based or algorithmic adjustment.

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

Since no information on a specific "training set" for the software modification is provided, there is also no information on how the ground truth for such a training set (if it existed) was established.

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