Nasal swabs, particularly nasopharyngeal (NP) swabs, are an important part of the diagnostic testing procedures for the SARS-CoV-2 virus that causes the current pandemic COVID-19 disease. The expanded demand for testing has increased the need for swabs, and 3D printing technology has emerged as a method to meet the demand. There are a variety of 3D-printed swabs currently available, with different designs and printing methods. The Veterans Health Administration (VHA) is evaluating the safety and functionality of a variety of 3D-printable NP swab designs for use in acquiring samples for COVID-19 diagnostic tests.
Testing protocols developed by the VHA can be downloaded from links in the table below, along with results from independent testing generously provided by Intrepid Automation. Click here to download a PDF of test results, up to date as of August 17, 2020. All swabs were purchased independently by the VHA. At present, only commercially-available swabs have been tested.
The areas for risk are as follows and designated for each requirement in the table below. Unless otherwise specified, all the swabs were designed for nasopharyngeal specimen collection.
Swab Requirements | Dx Test Compatibility |
Mechanical Failure |
Patient Injury |
Potential Harm | Testing Protocol |
Must be sterilizable | Unsterile swabs may introduce infection to the patient and may invalidate the test result | 3rd Party Report of Sterilization Validation | |||
Must be able to fit through the nasal cavity and reach the sampling location (e.g. nasopharynx, mid-turbinate region) | Inability to complete test; lost patient and staff time | Go/ No-Go Gauge
Dimensional Analysis |
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Sterilized swab should not substantially increase the risk of epistaxis (nose bleeds) as compared to the SOC* | Usually self-limited; in some cases, can lead to excessive blood loss and need for medical intervention | Abrasion Protocol Indentation Protocol |
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Sterilized swabs should not break while in the nasal cavity | Swab material retained in patient (e.g., nasal cavity) and/or mucosal injury, necessitating additional diagnostic testing and/ or procedures | Go/ No-Go Gauge
Fatigue Bending Protocol |
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Sterilized swab must collect and release a sufficient amount of SARS-CoV-2 sample to render a valid test result (benchmarked to standard of care) | Inaccurate test result, improper patient care delivered as a result | Adsorption Protocol
Intrepid Adsorption Results Intrepid Adsorption Results Table Elution Protocol |
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Sterilized swab must be compatible with (e.g., fit within) the transportation tube | Additional burden on testing staff (e.g., needing to cut a swab that is too long) | Dimensional Analysis Report
Breakpoint Function Test |
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Sterilized swab material must not interfere with the PCR test results | False negative test result, improper patient care delivered as a result | PCR Interference Protocol | |||
Sterilized swab material must be proven safe for mucus membrane contact | Mucus membrane irritation, adverse tissue reaction, patient illness | Material Biocompatibility Analysis report (ISO 10993) |
DEFINITIONS: SOC = Standard of Care; SARS-CoV-2 = the virus that causes COVID-19; PCR = Polymerase Chain Reaction, a step in the diagnostic test for COVID-19 that amplifies the viral genomic material of SARS-CoV-2, to indicate if the virus is present in the patient.
To support mechanical testing of 3D-printable nasopharyngeal swabs, the VHA designed custom devices. There are a total of 9 protocols that cover testing of 3D-printed swab design requirements. Protocols that require creation of fixtures or jigs are listed here.