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AllTest Viral Transport Medium (VTM) is intended for collection and transport of clinical specimens containing viral agents including Influenza A, Influenza B, Respiratory Syncytial Virus (RSV), and Rhinovirus from collection site to the testing laboratory. Specimens collected in the AllTest VTM can be processed using standard clinical laboratory operating procedure for viral culture.

The AllTest Viral Transport Medium is also intended for the stabilization and transportation of an unprocessed upper respiratory clinical specimen suspected of containing SARS-CoV-2 nucleic acid. The AllTest VTM is suitable for use with compatible legally marketed molecular diagnostic devices.

The AllTest Viral Transport Medium (VTM) device is comprised of a screw cap polypropylene tube filled with 3 mL VTM. The VTM tube is tightly closed with a polyethylene cap. The AllTest VTM contains Hank's Balanced Buffer solution (HBBS), proteins, sugar, and antimicrobials to provide stability to live viruses. The AllTest VTM also contains a pH indicator (phenol red) to provide a visual check on medium pH. The VTM appears clear and red in color. The packaging also includes a biohazard specimen bag.

The FDA 510(k) clearance letter for "AllTest Viral Transport Medium" describes the acceptance criteria and study that proves the device meets those criteria. Since this is a viral transport medium and not an AI/Software as a Medical Device (SaMD), the typical acceptance criteria for AI models (like sensitivity, specificity, AUC, etc.) and evaluation methods (such as MRMC studies, expert adjudication for ground truth) are not applicable. The device's performance is assessed based on its ability to maintain viral infectivity and nucleic acid stability over time and under different storage conditions.

Here's an analysis of the provided text, focusing on the relevant acceptance criteria and study details for this type of device:

Acceptance Criteria and Reported Device Performance

The core acceptance criteria revolve around the stability and recovery of viral agents within the AllTest VTM.

Study Details

Given the nature of the device (viral transport medium), the typical elements of an AI/SaMD study are not present. However, we can extract analogous information where applicable.

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

   • Shelf-life study: 15 tubes from each of three lots were tested at each time point for physical appearance and pH. 6 tubes were tested for microbial contamination.
   • Viral Recovery study: Viral recovery was assessed using three lots of media (3-month/new, 8-month/mid, and 12-month/old age lots). Contrived viral samples (pooled negative clinical matrix spiked with known concentration of virus) were used. These were then spiked onto swabs, transferred to VTM, and held at 4°C and 23-25°C for 0 and 48 hours. The specific number of replicates per condition is not explicitly stated beyond "serial 10-fold to a 96-well plate," but the overall methodology suggests controlled laboratory samples. Data provenance is implied to be laboratory-generated (contrived samples) rather than from specific countries or being retrospective/prospective clinical data.
   • Nucleic Acid Stability study:
     • LoD Determination: 20 replicates were tested at the preliminary LoD concentration (10 GCE/reaction) to confirm LoD.
     • Specimen Stability: Both clinical and contrived samples were used. Three lots of media (3-month/new, 8-month/mid, and 12-month/old age lots) were used. 50 µl of each sample was added to nasopharyngeal (NP) swab and transferred into VTM. Samples were stored at 4℃ and 23-25℃ for 0 and 48 hours. The specific number of clinical/contrived samples or replicates per condition is not explicitly stated. Data provenance includes both "clinical and contrived samples," suggesting some real clinical samples might have been used in addition to laboratory-prepared ones. This study appears to be laboratory-based testing.

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

   • Not applicable for this type of device. The "ground truth" for viral recovery and nucleic acid stability is established through quantitative laboratory measurements (TCID50 for viral recovery, Ct values for nucleic acid presence via PCR) against known input concentrations, not through expert consensus or interpretation of images.

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

   • Not applicable. This is a quantitative laboratory performance study, not a
     human-in-the-loop diagnostic accuracy study requiring adjudication.

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:

   • Not applicable. This device is a transport medium, not an AI/SaMD for diagnostic interpretation.

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

   • Not applicable. This is not an algorithm. The performance evaluation is for the physical medium itself.

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

   • For Viral Recovery: The "ground truth" or reference is the initial known concentration of the spiked virus (T=0 hour log10TCID50) to which the 48-hour recovery is compared. This is a quantitative laboratory reference.
   • For Nucleic Acid Stability: The "ground truth" or reference is the initial Ct value at T=0 hours from the spiked SARS-CoV-2 samples. This is a quantitative laboratory reference.

7. The sample size for the training set:

   • Not applicable. This is not a machine learning or AI device that requires a training set.

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

   • Not applicable, as there is no training set for this device.

Summary of the Study Design for AllTest Viral Transport Medium:

The studies conducted for the AllTest Viral Transport Medium are primarily laboratory-based performance studies designed to demonstrate the medium's ability to preserve the integrity of viral samples over specified timeframes and storage conditions. The methodology relies on established virological and molecular diagnostic techniques (viral culture/TCID50, PCR Ct values) using both contrived samples (known concentrations of viruses spiked into a matrix) and, for nucleic acid stability, also mentions the use of clinical samples. The "ground truth" is quantitative and established by the initial measurements of the spiked samples. The focus is on demonstrating stability and recovery rates rather than diagnostic accuracy or human performance.

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