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The Savanna HSV 1+2/VZV Assay is an automated, rapid multianalyte real-time PCR test for the simultaneous qualitative detection and differentiation of herpes simplex virus type 1, herpes simplex virus type 2, and varicella-zoster virus DNA isolated from human cutaneous or mucocutaneous lesion samples obtained from symptomatic patients suspected of active herpes simplex virus 1, herpes simplex virus 2 and/or varicella-zoster infection. This in vitro diagnostic test is intended to aid in the diagnosis of patients with signs or symptoms of herpes simplex virus type 1, herpes simplex virus type 2, and varicella-zoster virus infection.

The Savanna HSV 1+2/VZV Assay is intended to aid in the diagnosis of herpes simplex virus 1, herpes simplex virus 2 and varicella-zoster virus active infections. The results of this test should not be used as the sole basis for diagnosis, treatment or other management decisions and must be combined with clinical observations, patient history and/or epidemiological information. Negative results do not preclude herpes simplex virus type 1, herpes simplex virus type 2, or varicella-zoster virus infection that is not detected by a cutaneous or mucocutaneous lesion swab specimen. Positive results do not rule out co-infection with other organisms. Additional laboratory testing (e.g., viral culture, immunoassay, serology) may be necessary for patient evaluation. Savanna HSV 1+2/VZV Assay is for professional use. The Savanna HSV 1+2/VZV Assay is intended for use only with the Savanna instrument.

Warning: The Savanna HSV 1+2/VZV Assay is not intended for use with the cerebrospinal fluid (CSF) or to aid in the diagnosis of HSV or VZV infections of the central nervous system (CNS). The Savanna HSV 1+2/VZV Assay is not intended for use in prenatal screening.

The Savanna HSV 1+2/VZV Assay consists of a single, self-contained assay cartridge employing real-time PCR technology for use with the Savanna instrument to detect and differentiate DNA from herpes simplex virus type 1, herpes simplex virus type 2 and varicella-zoster virus. In approximately 24 minutes, this platform extracts, amplifies and detects DNA present in cutaneous or mucocutaneous lesion swab specimens obtained from symptomatic patients and placed in transport media.

To initiate the assay, a patient cutaneous or mucocutaneous lesion swab specimen in transport medium is transferred via the supplied transfer pipette to the Liguid Sample Port of the Test Cartridge. The user closes the Sample Port and inserts the Test Cartridge into the Savanna instrument, initiating sample processing. The sample containing human DNA is pushed out of the Sample Port by lysis buffer, which then rehydrates the Process Internal Control (IC), and together with the paramagnetic nucleic acid binding particles, are pumped into the extraction chamber. The solution is mixed, and virus and/ or bacteria are further lysed by sonication within the extraction chamber. Specimen and IC DNA are bound to, washed and then eluted off the paramagnetic particles. The purified specimen DNA and IC solution is used to rehydrate four individual lyophilized master mixes. Each master mix is pumped into a PCR chamber and Taq-man® multiplex real-time PCR reactions are carried out under optimized conditions, generating amplicons for the targeted pathogen (if present) and the Process Internal Control (IC).

Each master mix contains primers and dual-labeled probes unique for the pathogen targets and the IC. The probes are labeled with a fluorophore on one end and a quencher on the other end. Target DNA sequences are amplified by pathogen-specific primers and detected by correspondingly specific fluorescence probes. The IC targets are also amplified by specific primers and detected by an IC-specific fluorescence probe. A polymerase included in the master mix cleaves the probes bound to complementary DNA sequences, separating the fluorophore from the quencher. This step generates a signal and if it surpasses multiple defined thresholds, the sample is reported as positive for the detected target sequence.

The Savanna instrument will display the test results (Positive or Invalid) on the main bay screen.

The provided text describes the performance characteristics and clinical studies of the Savanna HSV 1+2/VZV Assay, which is an in vitro diagnostic (IVD) device for the detection and differentiation of herpes simplex virus type 1, herpes simplex virus type 2, and varicella-zoster virus DNA. It is not an AI/ML device in the context of typical FDA AI/ML medical device submissions, as it is a molecular diagnostic test. Therefore, many of the requested points regarding AI/ML device evaluation (like human-in-the-loop, expert consensus for ground truth, MRMC studies, number of experts for ground truth, adjudication methods, and sample size for training set) are not applicable to this type of device.

However, I can extract the acceptance criteria and performance data for this diagnostic assay as presented. The study aims to demonstrate substantial equivalence to a predicate device, the Solana HSV 1+2/VZV Assay (K162451), not to prove performance of an AI model.

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

The document does not explicitly state "acceptance criteria" in a tabulated format for the clinical performance. Instead, it presents the results of the clinical studies with Positive Percent Agreement (PPA) and Negative Percent Agreement (NPA) values with their confidence intervals, comparing the Savanna Assay to a commercially available RT-PCR comparator method. For laboratory studies, the acceptance criteria are implied by the results (e.g., >95% positivity for LoD, 100% detection for inclusivity, no interference/cross-reactivity).

I will present the clinical performance results as the "reported device performance" against an implied high standard of agreement with the comparator method.

Table: Reported Device Performance (Clinical Study 1 & 2)

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

• Clinical Study 1 (Fresh Samples):

  • Sample Size: 590 residual specimens (207 cutaneous, 383 mucocutaneous).
  • Data Provenance: United States, from symptomatic patients suspected of HSV-1, HSV-2, or VZV infection. Retrospective (residual specimens).

• Clinical Study 2 (Frozen Residual Samples):

  • Sample Size: 154 evaluable samples.
  • Data Provenance: Not explicitly stated but implies U.S. as it's a supplement to Clinical Study #1. Retrospective (residual frozen samples).

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

This is not applicable as this is an IVD device, not an AI/ML device relying on human expert labels for ground truth. The ground truth is established by a comparator FDA-cleared nucleic acid amplification test.

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

Not applicable. The ground truth is determined by the results of an FDA-cleared comparator nucleic acid amplification test, not by human adjudication of images.

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 is an IVD device, not an AI/ML device intended to assist human readers.

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

The device is a standalone diagnostic assay (real-time PCR test on the Savanna instrument). Its performance is evaluated independently against a comparator method. The results presented (PPA, NPA) represent this standalone performance.

7. The type of ground truth used

The ground truth for the clinical studies was established by comparison to FDA-cleared nucleic acid amplification tests (comparator method).

8. The sample size for the training set

Not applicable. This is not an AI/ML device that requires a "training set" in the context of machine learning model development. The robust performance of an IVD often relies on extensive analytical studies (LoD, inclusivity, cross-reactivity, precision, etc.) and clinical validation.

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

Not applicable, as there is no "training set" in the AI/ML sense. The analytical performance was established through various laboratory studies (e.g., Limit of Detection, Inclusivity, Cross-Reactivity, Precision) using well-characterized viral strains and matrices.

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