Polyester Nasal Swabs Collected in a Dry Tube are a Robust and Inexpensive, Minimal Self Collection Kit for SARS CoV 2 Testing

Background Polyester nasal swabs stored in saline or in a dry tube were evaluated as an alternative to foam nasal swabs for SARS-CoV-2 testing by reverse transcription quantitative polymerase chain reaction (RT-qPCR) since they may be inexpensively manufactured at high capacity. Methods Surrogate clinical specimens were prepared by inoculating foam and polyester nasal swabs with residual SARS-CoV-2 positive clinical specimens diluted in porcine or human matrix. Dry swab elution with phosphate buffered saline (PBS) was evaluated by vortex, swab swirling, and passive methodologies. Surrogate and clinical nasal specimen stability were evaluated at refrigerated (4°C) and elevated temperatures (40°C for 12 hours, 32°C hold) through 72 hours. Results Polyester swabs demonstrated equivalent performance to foam swabs for detection of low and high SARS-CoV-2 viral loads. Dry swab elution performed with PBS and mechanical disruption by vortex resulted in nearly complete quantitative recovery of virus. Dry polyester and foam surrogate specimens were stable through 72 hours both when refrigerated and after high temperature excursion, which simulated specimen transport without cold chain. Similarly, clinical specimens collected with polyester swabs and stored dry were stable through 72 hours in the presence and absence of cold chain. Polyester surrogate specimens stored in saline were stable through 72 hours refrigerated but only through 48 hours at elevated temperatures. Conclusions Polyester nasal swabs stored in dry collection tubes comprise a robust and inexpensive self-collection method for SARS-CoV-2 viral load testing, which is stable under conditions required for home collection and shipment to the laboratory. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement Funding for this work was provided through a grant from the Bill and Melinda Gates Foundation. In addition, Audere provided financial and other material support. Finally, Thermo Fisher Scientific provided some materials (such as reagents) toward the completion of the study. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: United Health Group protocol #2020-0002, approved by UHG Institutional Review Board All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes Upon request, the authors will make any and all data from the paper freely available to members of the research community. * AN : anterior nares RT-qPCR : reverse transcription quantitative PCR PBS : phosphate buffered saline CDC : Centers for Disease Control and Prevention FDA : U.S. Food and Drug Administration PPE : personal protective equipment VTM : viral transport media LoD : limit of detection EUA : Emergency Use Authorization Ct : cycle threshold GCE : genomic copy equivalents