Design and Multicenter Clinical Validation of a 3-Dimensionally Printed Nasopharyngeal Swab for SARS-CoV-2 Testing

Abstract

IMPORTANCE Three-dimensionally printed nasopharyngeal swabs (3DP swabs) have been used to mitigate swab shortages during the coronavirus disease 2019 (COVID-19) pandemic. Clinical validation for diagnostic accuracy and consistency, as well as patient acceptability, is crucial to evaluate the swab's performance.OBJECTIVE To determine the accuracy and acceptability of the 3DP swab for identifying severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). DESIGN, SETTING, AND PARTICIPANTSA diagnostic study was conducted from May to July 2020 at 2 tertiary care centers in Singapore with different reference swabs (FLOQSwab [COPAN Diagnostics] or Dacron swab [Deltalab]) and swab processing techniques (wet or dry) to evaluate the performance of the 3DP swab compared with traditional, standard-of-care nasopharyngeal swabs used in health care institutions. The participants were patients with COVID-19 in the first 2 weeks of illness and controls with acute respiratory illness with negative test results for SARS-CoV-2. Paired nasopharyngeal swabs were obtained from the same nostril and tested for SARS-CoV-2 by reverse-transcriptase polymerase chain reaction. The sequence of swabs was randomized based on odd and even participant numbers.MAIN OUTCOMES AND MEASURES Primary outcome measures were overall agreement (OA), positive percentage agreement (PPA), and negative percentage agreement of the 3DP swab compared with reference swabs. Secondary outcome measures were the correlation of cycle threshold (Ct) values of both swabs. RESULTSThe mean (SD) age of participants was 45.4 (13.1) years, and most participants were men (87 of 89 [97.8%]), in keeping with the epidemiology of the COVID-19 pandemic in Singapore. A total of 79 patients with COVID-19 and 10 controls were recruited. Among the patients with COVID-19, the overall agreement and PPA of the 3DP swab was 91.1% and 93.5%, respectively, compared with reference swabs. The PPA was 100% for patients with COVID-19 who were tested within the first week of illness. All controls tested negative. The reverse-transcriptase polymerase chain reaction Ct values for the ORF1ab and E-gene targets showed a strong correlation (intraclass correlations coefficient, 0.869-0.920) between the 3DP and reference swab on independent testing at each institution despite differences in sample processing. Discordant results for both gene targets were observed only at high Ct values. CONCLUSIONS AND RELEVANCEIn this diagnostic study of 79 patients with COVID-19 and 10 controls, the 3DP swab performed accurately and consistently across health care institutions and could help mitigate strained resources in the escalating COVID-19 pandemic.

Original article: novelty of Canadian manufacture nasopharyngeal swabs for collection of samples being tested for SARS-CoV-2 in a pandemic setting

“…Although some of the test swabs differed slightly in mean Ct values, none of them fell below the pre-specified threshold of a difference ≥ 2 Ct. This renders them very similar, as confirmed by the overall accuracy of RT-PCR testing, which is highly sensitive to small amounts of material ( 10 ).…”

Improving Nasopharyngeal Swab Technique via Simulation for Frontline Workers

“…It was used to overcome material shortage to produce 3D printed nasal swabs and face shields, as well as to fill training gaps caused by a large inflow of health care workers to COVID‐19 frontline centers. 23 , 24 Sananès et al 25 presented a realistic 3D printed nasal swab simulator based on CT and MRI scans of the nasal and pharyngeal cavities as a potential educational tool on NP swab technique. Nonetheless, despite the similarities with the NP swab simulator used in the current study in respect to realism in design and potential for procedural feedback, no pilot data have been published yet concerning its usability in a real‐world scenario such as the COVID‐19 testing centers.…”

“…Three‐dimensional printing technology has played an important role in fighting the SARS‐CoV‐2 pandemic in several aspects. It was used to overcome material shortage to produce 3D printed nasal swabs and face shields, as well as to fill training gaps caused by a large inflow of health care workers to COVID‐19 frontline centers 23,24 . Sananès et al 25 presented a realistic 3D printed nasal swab simulator based on CT and MRI scans of the nasal and pharyngeal cavities as a potential educational tool on NP swab technique.…”

Performance of three-dimensional printed nasopharyngeal swabs for COVID-19 testing

“…To determine the ability of swabs to retain and release viral samples, swabs were used to collect samples from virus infected mucus mimic, as well as from virus infected cells. Swabs (three replicates) were immersed in 1.5 mL in mucus mimic spiked with 1 × 10 6 PFU murine coronavirus (mouse hepatitis virus, MHV) 14 , 15 and rotated for 15 s. A second set of swab samples (three replicates) were used to swab a monolayer (one well of a 96-well plate/replicate) of virus infected 17CL-1 mouse epithelial cells immersed in mucus mimic. Infected swabs were placed in a fresh tube containing 2 mL of media (Dulbecco’s Modified Eagle Medium (Thermo Scientific), 2% FBS, Pen/Strep antibiotic) and allowed to incubate at room temperature for 2.5 h for the mucus mimic or overnight at 4ºC for the infected cells.…”