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The cobas® SARS-CoV-2 Nucleic acid test for use on the cobas® SARS-CoV-2) is an automated, realtime reverse transcriptase polymerase chain reaction (RT-PCR) test intended for the rapid in vitro qualitative detection of nucleic acid from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in anterior nasal (nasal) and nasopharyngeal swab specimens collected from individuals with signs and symptoms of respiratory tract infection (i.e., symptomatic). Additionally, this test is intended to be used with nasal and necimens collected from individuals without signs and symptoms suspected of COVID-19 (i.e., asymptomatic).

The cobas® SARS-CoV-2 performed on the cobas® Liat® System is intended for use as an aid in the diagnosis of COVID-19 if used in conjunction with other clinical, epidemiologic, and laboratory findings. SARS-CoV-2 RNA is generally detectable in nasal and nasopharyngeal swab specimens during the acute phase of infection.

Positive results are indicative of the presence of SARS-CoV-2 RNA. Positive results do not rule out co-infection with other microorganisms.

A negative result from an asymptomatic individual is presumptive. Additionally, a negative result obtained with a nasal swab collected from an asymptomatic patient should be followed up by testing at least twice over three days with at least 48 hours between tests.

Negative results do not preclude SARS-CoV-2 infection.

The results of this test should not be used as the sole basis for diagnosis, treatment management decisions.

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

The cobas® SARS-CoV-2 Nucleic acid test for use on the cobas® Liat® System (cobas® SARS-CoV-2) uses real-time reverse transcriptase polymerase chain reaction (RT-PCR) technology to rapidly (approximately 20 minutes) detect SARS-CoV-2 virus from nasopharyngeal and nasal swabs. The automation, small footprint, and easy-to-use interface of the cobas® Liat® System enable performance of this test to occur at the POC or in a clinical laboratory setting.

The cobas® SARS-CoV-2 assay is performed on the cobas® Liat® Analyzer which automates and integrates sample purification, nucleic acid amplification, and detection of the target sequence in biological samples using real-time RT-PCR assays. The assay targets both the ORF1 a/b nonstructural region and nucleocapsid protein gene that are unique to SARS-CoV-2. An Internal Process Control (IPC) is also included. The IPC is present to control for adequate processing of the target virus through steps of sample purification, nucleic acid amplification, and to monitor the presence of inhibitors in the RT-PCR processes.

Here's an analysis of the acceptance criteria and study findings for the "cobas SARS-CoV-2 Nucleic acid test for use on the cobas Liat System" based on the provided text:

Acceptance Criteria and Reported Device Performance

The acceptance criteria are implied by the clinical performance evaluation results, specifically the Positive Percent Agreement (PPA) and Negative Percent Agreement (NPA) with a composite comparator method. While explicit acceptance criteria values are not stated (e.g., "PPA must be >X%"), the device's performance is presented to demonstrate its effectiveness.

Study Information

1. Sample sizes used for the test set and data provenance:

   • Clinical Performance Evaluation (Test Set):
     • Evaluable NPS samples: 1874 (fresh and frozen)
       • Symptomatic: 673 NPS
       • Asymptomatic: 1201 NPS (413 suspected, 788 no suspicion)
     • Evaluable NS samples: 1872 (fresh and frozen, including 1 indeterminate result)
       • Symptomatic: 674 NS
       • Asymptomatic: 1198 NS (411 suspected, 787 no suspicion)
     • Frozen Samples (included in above totals): 23 positive and 23 negative NPS specimens, and 23 positive and 23 negative NS specimens.
     • Data Provenance: Prospectively collected clinical specimens from February-June 2022 (fresh samples) and earlier during the COVID-19 pandemic (March-June 2021) for frozen samples. The document does not specify the country of origin, but it implies collection within "10 point-of-care healthcare facilities" without further geographic detail.

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

   • The ground truth for the test set was established using a composite comparator method consisting of "three highly sensitive FDA-EUA-authorized laboratory-based RT-PCR assays."
   • The document does not specify the number or qualifications of human experts involved in establishing this ground truth. The ground truth relies on the performance of these reference RT-PCR assays.

3. Adjudication method for the test set:

   • The text describes a "composite comparator method" using "three highly sensitive FDA-EUA-authorized laboratory-based RT-PCR assays." This implies a form of consensus or a predefined algorithm for combining the results of these three assays to establish the definitive positive or negative status. However, the specific adjudication rules (e.g., "2 out of 3 positive for overall positive") are not explicitly described.

4. 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 MRMC comparative effectiveness study involving human readers or AI assistance is described. This study focuses on the standalone performance of the cobas SARS-CoV-2 test.

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

   • Yes, a standalone performance study was done. The entire clinical performance evaluation section (Section 7) describes the performance of the "cobas SARS-CoV-2 test" (the device/algorithm) against a composite comparator method (ground truth) without human intervention in the result interpretation of the device. The device itself is an automated RT-PCR test.

6. The type of ground truth used:

   • The ground truth used was a composite comparator method based on the results from "three highly sensitive FDA-EUA-authorized laboratory-based RT-PCR assays." This is a form of laboratory reference standard.

7. The sample size for the training set:

   • The document describes a clinical performance evaluation (test set) and analytical studies. It does not provide information about the sample size of a specific "training set" for the device, as it is a molecular diagnostic test rather than a machine learning algorithm that typically undergoes explicit training on large datasets in the way an AI image analysis product would. The development (implied "training" in a broader sense for assay optimization) would have used various samples, but these are not explicitly detailed as a distinct training set in the provided text.

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

   • As no explicit "training set" with established ground truth is described in the context of typical AI/ML development, this question cannot be answered from the provided text. The assay development would involve extensive analytical validation using characterized viral samples and clinical specimens validated by reference methods, which broadly contribute to optimizing the assay's performance.

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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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