Puritan PurSafe Plus Collection and Transport System is an enclosed system intended for the collection, inactivation, and preservation of human upper respiratory specimens suspected of containing SARS-CoV-2. Puritan PurSafe Plus Collection and Transport System can be used for collection, transport, and storage of specimens at 2-4°C and 25-30°C. Specimens collected and stored in the PurSafe Plus Collection and Transport System are suitable for use with legally marketed molecular diagnostic devices.

Device Description

Puritan PurSafe Plus Collection and Transport System is comprised of a peel pouch containing a sterile polyester flock swab applicator for collecting clinical specimens and a polypropylene vial containing 1mL PurSafe Plus buffer. PurSafe Plus MK buffer ensures stability of Sars Cov-2 during sample transport/storage at refrigerated to ambient temperature (4-30°C) and is intended to inactivate Sars Cov-2.

AI/ML Overview

Acceptance Criteria and Device Performance Study for Puritan PurSafe Plus Collection and Transport System

This document outlines the acceptance criteria and reports on the study that demonstrates the Puritan PurSafe Plus Collection and Transport System meets these criteria, based on the provided FDA 510(k) clearance letter.

1. Table of Acceptance Criteria and Reported Device Performance

Acceptance Criteria Category	Specific Criteria	Puritan PurSafe Plus Performance
Limit of Detection (LOD)	The device should not adversely affect the stated detection limits of the downstream molecular diagnostic device for SARS-CoV-2 viral RNA. Specifically, it should achieve positive detection at an estimated concentration of 64 genome copies/mL when used with the Cepheid GeneXpert® IV system (Xpert Xpress Cov-2/Flu/RSV).	Met. The study indicated positive detection of viral RNA at an estimated concentration of 64 genome copies/mL using the Cepheid GeneXpert® IV system. Quantitative droplet digital PCR showed no significant loss of detection for samples stored in Nasal + PurSafe Plus compared to just nasal matrix alone. No significant differences in SARS-CoV-2 RNA positive detection were observed among PurSafe lots and the predicate Zymo product. Additionally, 20 replicates at the LOD concentration (64 genome copies/mL) over six days yielded positive detection for all replicates, with Ct values within 2 units.
SARS-CoV-2 RNA Stability	The device should preserve SARS-CoV-2 RNA for up to 28 days at temperatures of 4°C and 30°C, demonstrating no significant loss in the ability to positively detect SARS-CoV-2 using the Cepheid GeneXpert® IV system.	Met. For all three Puritan lots and the Zymo lot, samples stored at 4°C and 30°C for up to 28 days showed no significant loss in the ability to positively detect SARS-CoV-2. Mean Ct values for all samples across all time points and temperatures were less than 3 Ct units from baseline. All Puritan lots were found to be equivalent to the Zymo product in preservation of SARS-CoV-2 RNA.
Viral Inactivation	The device's buffer should be able to inactivate SARS-CoV-2 virus after exposure.	Met. SARS-CoV-2 virus was inactivated after exposure to three different lots of Puritan PurSafe Plus buffer (at 1:0 dilution) after a minimum of 1 minute of exposure. Cytotoxicity was observed at a 1/10 dilution of the buffer but not at 1/60, informing subsequent inactivation study dilutions.

2. Sample Size and Data Provenance

Test Set Sample Size:
- LOD Study: N=24 for the initial assessment (6 concentrations x 2 replicates x 2 lots). N=20 for the confirmatory LOD (20 replicates at 64 genome copies/mL).
- Stability Study: N=72 (4 lots x 5 time points x 2 incubation temperatures x 2 replicates).
Data Provenance: The data was generated using heat-inactivated SARS-CoV-2 virus (BEI Resources; ATCC # VR-1986HK) spiked into clinically negative human nasal matrix (Lee Biosolutions, Maryland Heights, MO). This suggests retrospective analysis on a prepared sample matrix rather than prospective patient samples. The country of origin of the data is not explicitly stated, but the vendors for the virus and nasal matrix are US-based.

3. Number of Experts and Qualifications for Ground Truth

The document does not mention the use of human experts to establish ground truth for the performance studies.
The ground truth for the studies was based on the known concentration of spiked heat-inactivated SARS-CoV-2 virus and the analytical performance of the Cepheid GeneXpert® IV system and droplet digital PCR.

4. Adjudication Method for the Test Set

No adjudication method is described. The studies rely on quantitative measurements of viral RNA detection using laboratory instruments (Cepheid GeneXpert® IV and ddPCR) and direct observation of viral inactivation.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

No MRMC comparative effectiveness study was done. This device is a collection and transport system, not an interpretive diagnostic AI algorithm that would typically involve human readers. Therefore, the effect size of human readers improving with or without AI assistance is not applicable.

6. Standalone Algorithm Performance Study

A standalone performance study was done. The studies described (LOD, Stability, Inactivation) assess the performance of the Puritan PurSafe Plus Collection and Transport System (the "device" or "algorithm" in this context) directly, without human interpretation or intervention in the diagnostic process beyond laboratory procedures. The system's ability to preserve and inactivate the virus, and not interfere with downstream molecular detection, is evaluated independently.

7. Type of Ground Truth Used

The type of ground truth used was analytical ground truth and virological ground truth.
- Analytical Ground Truth: For the LOD and Stability studies, known concentrations of heat-inactivated SARS-CoV-2 (quantified in genome copies/mL) were spiked into confirmed clinically negative nasal matrix. The expected outcome was the detection of this known concentration by the downstream molecular diagnostic device.
- Virological Ground Truth: For the Inactivation study, the presence or absence of viable SARS-CoV-2 virus after exposure to the buffer was the ground truth, assessed by exposing VeroE6 cells to the treated virus.

8. Sample Size for the Training Set

The document does not specify a training set sample size. This is because the device is a physical collection and transport system, not an AI or machine learning model that typically requires a separate training set. The performance studies described are for validation, not model training.

9. How Ground Truth for the Training Set Was Established

As there is no explicit training set for an AI/ML model, the concept of establishing ground truth for a training set is not applicable to this device. The ground truth described in point 7 is for the validation of the device's functional performance.

Summary

FDA 510(k) Clearance Letter - Puritan PurSafe Plus Collection and Transport System

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U.S. Food & Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993
www.fda.gov

Doc ID # 04017.07.05

May 27, 2025

Puritan Medical Products LLC
Mehdi Karamchi
V.P. of Scientific Affairs
31 School Street PO Box 149
Gulford, Maine 04443-0149

Re: K242820
Trade/Device Name: Puritan PurSafe Plus Collection and Transport System
Regulation Number: 21 CFR 866.2950
Regulation Name: Microbial Nucleic Acid Storage And Stabilization Device
Regulatory Class: Class II
Product Code: QBD
Dated: April 25, 2025
Received: April 25, 2025

Dear Mehdi Karamchi:

We have reviewed your section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (the Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. Although this letter refers to your product as a device, please be aware that some cleared products may instead be combination products. The 510(k) Premarket Notification Database available at https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm identifies combination product submissions. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.

If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.

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K242820 - Mehdi Karamchi Page 2

Additional information about changes that may require a new premarket notification are provided in the FDA guidance documents entitled "Deciding When to Submit a 510(k) for a Change to an Existing Device" (https://www.fda.gov/media/99812/download) and "Deciding When to Submit a 510(k) for a Software Change to an Existing Device" (https://www.fda.gov/media/99785/download).

Your device is also subject to, among other requirements, the Quality System (QS) regulation (21 CFR Part 820), which includes, but is not limited to, 21 CFR 820.30, Design controls; 21 CFR 820.90, Nonconforming product; and 21 CFR 820.100, Corrective and preventive action. Please note that regardless of whether a change requires premarket review, the QS regulation requires device manufacturers to review and approve changes to device design and production (21 CFR 820.30 and 21 CFR 820.70) and document changes and approvals in the device master record (21 CFR 820.181).

Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801 and Part 809); medical device reporting (reporting of medical device-related adverse events) (21 CFR Part 803) for devices or postmarketing safety reporting (21 CFR Part 4, Subpart B) for combination products (see https://www.fda.gov/combination-products/guidance-regulatory-information/postmarketing-safety-reporting-combination-products); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820) for devices or current good manufacturing practices (21 CFR Part 4, Subpart A) for combination products; and, if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR Parts 1000-1050.

All medical devices, including Class I and unclassified devices and combination product device constituent parts are required to be in compliance with the final Unique Device Identification System rule ("UDI Rule"). The UDI Rule requires, among other things, that a device bear a unique device identifier (UDI) on its label and package (21 CFR 801.20(a)) unless an exception or alternative applies (21 CFR 801.20(b)) and that the dates on the device label be formatted in accordance with 21 CFR 801.18. The UDI Rule (21 CFR 830.300(a) and 830.320(b)) also requires that certain information be submitted to the Global Unique Device Identification Database (GUDID) (21 CFR Part 830 Subpart E). For additional information on these requirements, please see the UDI System webpage at https://www.fda.gov/medical-devices/device-advice-comprehensive-regulatory-assistance/unique-device-identification-system-udi-system.

Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to https://www.fda.gov/medical-devices/medical-device-safety/medical-device-reporting-mdr-how-report-medical-device-problems.

For comprehensive regulatory information about medical devices and radiation-emitting products, including information about labeling regulations, please see Device Advice (https://www.fda.gov/medical-devices/device-advice-comprehensive-regulatory-assistance) and CDRH Learn (https://www.fda.gov/training-and-continuing-education/cdrh-learn). Additionally, you may contact the Division of Industry and Consumer Education (DICE) to ask a question about a specific regulatory topic. See the DICE website (https://www.fda.gov/medical-devices/device-advice-comprehensive-regulatory-

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K242820 - Mehdi Karamchi Page 3

assistance/contact-us-division-industry-and-consumer-education-dice) for more information or contact DICE by email (DICE@fda.hhs.gov) or phone (1-800-638-2041 or 301-796-7100).

Sincerely,

Noel J. Gerald -S

Noel J. Gerald, Ph.D.
Deputy Division Director
Division of Microbiology Devices
OHT7: Office of In Vitro Diagnostics
Office of Product Evaluation and Quality
Center for Devices and Radiological Health

Enclosure

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FORM FDA 3881 (8/23) Page 1 of 1

DEPARTMENT OF HEALTH AND HUMAN SERVICES
Food and Drug Administration

Indications for Use

Form Approved: OMB No. 0910-0120
Expiration Date: 07/31/2026
See PRA Statement below.

510(k) Number (if known): K242820

Device Name: Puritan PurSafe Plus Collection and Transport System

Indications for Use (Describe):

Type of Use (Select one or both, as applicable):
☒ Prescription Use (Part 21 CFR 801 Subpart D)
☐ Over-The-Counter Use (21 CFR 801 Subpart C)

CONTINUE ON A SEPARATE PAGE IF NEEDED.

This section applies only to requirements of the Paperwork Reduction Act of 1995.

DO NOT SEND YOUR COMPLETED FORM TO THE PRA STAFF EMAIL ADDRESS BELOW.

The burden time for this collection of information is estimated to average 79 hours per response, including the time to review instructions, search existing data sources, gather and maintain the data needed and complete and review the collection of information. Send comments regarding this burden estimate or any other aspect of this information collection, including suggestions for reducing this burden, to:

Department of Health and Human Services
Food and Drug Administration
Office of Chief Information Officer
Paperwork Reduction Act (PRA) Staff
PRAStaff@fda.hhs.gov

"An agency may not conduct or sponsor, and a person is not required to respond to, a collection of information unless it displays a currently valid OMB number."

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510(k) Summary

Puritan® PurSafe® Plus Collection and Transport System

510(k) Submission # K242820

1.0 Sponsor

Puritan Medical Products LLC
31 School St., Guilford, ME
04443

Contact: Mehdi Karamchi
Telephone Number: 207-876-3311
Fax Number: 207-876-2680
Date: September 16, 2024

2.0 Device Name

Classification Name: Microbial nucleic acid storage and stabilization device
Common Name: Puritan® PurSafe® Plus Collection and Transport System
Proprietary Name: Puritan® PurSafe® Plus Collection and Transport System

3.0 Regulatory Information

A. Regulatory Section: 21 CFR 866.2950
B. Classification: Class II
C. Product Code: QBD
D. Panel: Microbiology

4.0 Predicate Device

Zymo Research DNA/RNA Shield Collection Tube

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510(k) Number: K202641

5.0 Device Description

PurSafe Plus MK buffer ensures stability of Sars Cov-2 during sample transport/storage at refrigerated to ambient temperature (4-30°C) and is intended to inactivate Sars Cov-2.

6.0 Intended Use

7.0 Test Device and Predicate Device Comparison

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Item	Test Device	Predicate
		Zymo Research DNA/RNA Shield Collection Tube
		510(k) Number: K202641
Intended USE	Puritan PurSafe Plus Collection and Transport System is an enclosed system intended for the collection, inactivation, and preservation of human upper respiratory specimens suspected of containing SARS-CoV-2. Puritan PurSafe Plus Collection and Transport System can be used for collection, transport, and storage of specimens at 2-4°C and 25-30°C. Specimens collected and stored in the PurSafe Plus Collection and Transport System are suitable for use with legally marketed molecular diagnostic devices.	The DNA/RNA Shield™ collection tube is intended for the stabilization and inactivation of upper and lower respiratory human specimens suspected of containing SARS-CoV-2. These devices can be used for collection transport and storage of specimens at ambient temperatures (20-25°C). Specimens collected and stored in a DNA/RNA Shield™ collection tube are suitable for use with legally marketed molecular diagnostic devices.
Single-use Device	Yes	Same
Medium Formulation	Inactivation BufferSaltspH Buffering agentMolecular Grade Water	Inactivation bufferSaltspH BufferWater
pH	8.3 ± 0.2	5.0-7.0
Storage Temperature	4-30°C (refrigerated and room temperature)	20-25°C (ambient temperature)
Container	Polypropylene conical bottom vial	Same

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Item	Test Device	Predicate
Product Configuration	Medium in vial & capSystem including Medium and swab in peel pouch option.	Same
Swab Shaft	Plastic	Same
Swab Tip	Flock Swab	Same
Shelf Life	24 months	24 months
Analyte	RNA	RNA

8.0 Performance Characteristics

Limit of Detection (LOD)

Limit of Detection studies were carried out to assess the minimum concentration of viral RNAs from Sars-CoV-2 detectable via the Cepheid GeneXpert® IV system using the 4 Plus TEST KIT, (COV-2/FLU/RSV PLUS X PERT XPRESS) (Cat #: XP3COV2/FLU/RSV-10). The stated limit of detection for the Cepheid Xpert Xpress Cov-2/Flu/RSV is 64 copies/mL for nasal swab specimens (XP3COV2/FLURSV-1).

The LOD studies were performed with heat-inactivated Sars-Cov-2 (BEI Resources; ATCC # VR-1986HK, Lot # 70037781) at a stated initial concentration of 4.2 x10⁵ genome copies per µl. LOD assays were carried out on one lot of Puritan PurSafe Plus Collection and Transport System (Lot 240312, expiration 3/12/2026) and one lot of the Zymo product (DNA/RNA Shield™ R1107 Lot 236390 expiration 5/1/2026).

Performance of both products were evaluated in clinically negative (confirmed by ddPCR) nasal matrix (Lee Biosolutions, Maryland Heights, MO). The LOD was assessed for Sars-CoV-2 viral RNA for estimated final concentrations of 256, 128, 64, 32, 16 and 0 genome copies/mL. For both the PurSafe lot and Zymo, two replicates were quantified at each concentration (N=24; 6 concentrations x 2 replicates x two lots). Additionally, to assess possible effects of the Puritan PurSafe Plus alone, detection was assessed in the nasal matrix alone and compared against nasal matrix with Puritan PurSafe Plus using droplet digital PCR.

For the Puritan PurSafe Plus as well as for the Zymo lot LOD studies indicated positive detection of viral RNA using the Cepheid GeneXpert® IV system to an estimated concentration of 64 genome copies/mL. This is the stated limit of detection for the Cepheid Xpert Xpress Cov-2/Flu/RSV system. This study indicates that the use of Puritan PurSafe has no adverse effect on the stated detection limits of the Cepheid instrument. Additionally, quantitative droplet digital PCR showed no significant loss of detection for samples stored in Nasal + PurSafe Plus compared to just nasal matrix alone. There were no significant differences in Sars-CoV-2 RNA

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positive detection among PurSafe lots and Zymo. Additionally, 20 replicates at the LOD concentration of 64 genome copies/mL carried out over six days indicated positive detection for all replicates. Less than two Ct values separated the highest (37.6) and lowest (36.0) values.

Stability Studies

The objective of this study was to assess the ability of the PurSafe Plus Collection and Transport System to store viral RNAs from Sars-CoV-2 for up to 28 days at ideal and relatively high (4°C and 30°C) temperatures. As was done for the LOD studies, heat inactivated Sars-CoV-2 (BEI Resources; ATCC # VR-1986HK, Lot # 70037781) were spiked into the confirmed clinically negative Nasal matrix (Lee Biosolutions, Maryland Heights, MO) with the transport media to achieve an estimated final concentrations 2-3 times the LOD (100 genome copies/mL). Three Puritan lots were evaluated; "new" product (Lot 240312, expiration 3/12/2026), "mid" product (Lot 230207, expiration 2/7/2025) and an "expired" product (Lot 221109, expiration 9/11/2024) and one lot of the Zymo product (DNA/RNA Shield™ R1107 Lot 236390 expiration 5/1/2026).

RNA detection for each lot (4), time point (5) and incubation temperature (2) was assessed with two replicates (N=72) using a Cepheid GeneXpert® IV system using the 4 Plus TEST KIT, (COV-2/FLU/RSV PLUS X PERT XPRESS).

For all three Puritan lots and the Zymo lot in clinically negative matrices all samples yielded sufficient RNA for positive detection using the Cepheid GeneXpert® IV system. For all samples stored at 4°C and 30°C for up to 28 days showed no significant loss in the ability to positively detect Sars-CoV-2 in the Cepheid GeneXpert® IV system. Mean Ct values for all samples across all time points and temperatures were less 3 Ct units from baseline (Time = 0) values. All Puritan lots were equivalent to the Zymo product in preservation of Sars-CoV-2 RNA for up to 28 days at both 4°C and 30°C.

Inactivation

Uninfected VeroE6 cells were exposed to the Puritan PurSafe Plus Buffer to assess possible cytotoxicity. Cytotoxicity with the PurSafe Plus buffer alone was observed at a dilution of 1/10 but the 1/60th dilution had healthy cells. For subsequent inactivation studies, a 1:60 dilution was used for the Puritan PurSafe Plus Collection and Transport System. SARS-CoV-2 virus was inactivated after exposure to the 3 different lots of Puritan PurSafe Plus buffer (at 1:0 dilution) after a minimum of 1 minute of exposure.

Based upon statistical analyses we conclude that the Puritan PurSafe Plus Collection and Transport System performed equally to the commercial product, Zymo DNA/RNA Shield™.

9.0 Conclusion

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The conclusions drawn from the nonclinical tests demonstrate the device is as safe and effective as the legally marketed device identified above.

Regulation Number and Section

§ 866.2950 Microbial nucleic acid storage and stabilization device.

(a)
Identification. A microbial nucleic acid storage and stabilization device is a device that consists of a container and reagents intended to stabilize microbial nucleic acids in human specimens for subsequent isolation and purification of nucleic acids for further molecular testing. The device is not intended for preserving morphology or viability of microorganisms.(b)
Classification. Class II (special controls). The special controls for this device are:(1) The intended use for the labeling required under § 809.10 of this chapter must include a detailed description of microorganisms and types of human specimens intended to be preserved.
(2) The labeling required under § 809.10(b) of this chapter must include the following:
(i) A detailed device description, including all device components;
(ii) Performance characteristics from applicable analytical studies, including nucleic acid stability and microorganism inactivation;
(iii) A limiting statement that erroneous results may occur when the transport device is not compatible with molecular testing; and
(iv) A limiting statement that the device has only been validated to preserve the representative microorganisms used in the analytical studies.
(3) Design verification and validation must include the following:
(i) Overall device design, including all device components and all control elements incorporated into the analytical validation procedures;
(ii) Thorough description of the microorganisms and methodology used in the validation of the device including, extraction platforms and assays used for the detection of preserved nucleic acids; and
(iii) The limit of detection (LoD) of the molecular test used to establish microorganism nucleic acid stability.