Design and clinical validation of a 3D-printed nasopharyngeal swab for COVID-19 testing

Tay, J. K.; Cross, G. B.; Lee, C. K.; Yan, B.; Loh, J.; Lim, Z. Y.; Ngiam, N.; Chee, J.; Gan, S. W.; Saraf, A.; Chow, W. T. E.; Goh, H. L.; Siow, C. H.; Lian, D. W.; Loh, W. S.; Loh, K. S.; Chow, V. T.; Wang, D. Y.; Fuh, J. Y.; Yen, C.-C.; Wong, J. E.; Allen, D. M.

We describe the development and validation of a novel 3D-printed nasopharyngeal swab for the identification of SARS-CoV-2. We subjected the novel swab to mechanical and fluid absorption testing ex-vivo, and confirmed its ability to retain and release murine coronavirus and SARS-CoV-2. Compared to the Copan FLOQSwab, the novel swab displayed excellent correlation of RT-PCR cycle threshold values on paired clinical testing in COVID-19 patients, at r = 0.918 and 0.943 for the SARS-CoV-2 ORF1/a and sarbecovirus E-gene respectively. Overall positive and negative percent agreement was 90.6% and 100% respectively on a dual-assay RT-PCR platform, with discordant samples observed only at high cycle thresholds. When carefully designed and tested, 3D-printed swabs are a viable alternative to traditional swabs and will help mitigate strained resources in the escalating COVID-19 pandemic.