Evaluation of saliva self-collection devices for SARS-CoV-2 diagnostics

Abstract

There is an urgent need to expand testing for SARS-CoV-2 and other respiratory pathogens as the global community struggles to control the COVID-19 pandemic. Current diagnostic methods can be affected by supply chain bottlenecks and require the assistance of medical professionals, impeding the implementation of large-scale testing. Self-collection of saliva may solve these problems, as it can be completed without specialized training and uses generic materials. In this study, we observed thirty individuals who self-collected saliva using four different collection devices and analyzed their feedback. Two of these devices, a funnel and bulb pipette, were used to evaluate at-home saliva collection by 60 individuals. All devices enabled the safe, unsupervised self-collection of saliva. The quantity and quality of the samples received were acceptable for SARS-CoV-2 diagnostic testing, as determined by RNase P detection. Here, we demonstrate inexpensive, generic, buffer free collection devices suitable for unsupervised and home saliva self-collection.

Figure 1:. Collection devices are inexpensive, easy to use, and yield testable samples.

Survey responses were reported from strongly disagree to strongly agree. (a) The four collection devices tested are inexpensive and provide users with a range of features to choose from. Prices at time of publication are shown in US dollars. (b) Participants reported being self-sufficient and confident in their ability to correctly collect saliva samples (from Figure S2). The questions are displayed above the corresponding graphs. The percentage response value for each device is shown above each bar. Two sets of participant responses were excluded because one participant did not provide a response for all four devices and one did not understand the response scale. Abbreviations: P = pipette tip, C = collection aid, F = funnel, B = bulb pipette.

Figure 2.. At-home saliva collection kit components suitable for sample collection.

a) Each of the participants were sent an at-home collection kit comprised of either a funnel (i) or bulb pipette (ii) with a labeled screw-cap tube (iii), patient identifier sticker (iv), biohazard collection bag with absorbent sheet (v), FedEx UN 3373 Pak (vi), an alcohol pad (vii), and box for return shipment (viii). b) Participant confidence in at-home self-collection of saliva when using either a funnel or bulb pipette (from Figure S4). Survey responses were reported on a scale of 1 (strongly disagree) to 5 (strongly agree). Overall, there was no significant difference between the collection devices in relation to the participant’s confidence and ability to use either device. The questions are displayed above the corresponding graphs. Abbreviations: F = funnel, B = bulb pipette.

Figure 3. The quality of the samples was adequate for testing with a PCR-based assay.

Laboratory survey questions pertaining to the quality of the samples are shown on the x-axis (from Figures S3, S5). Data points represent the mean response, green dots represent samples collected from the pilot study and blue dots represent samples collected from the at-home collection kit. Survey responses were reported on a scale of 1 (strongly disagree) to 5 (strongly agree). Samples with less favorable responses are highlighted in red. Mean and standard deviation (st. dev.) are shown in black. The graph on the right shows the cycle threshold (Ct) values for the internal control RNAse P (RP) from each of the saliva samples submitted. The blue and green dots represent Ct value per participant. Ct values over 35 are considered invalid and is highlighted in gray. P-value is shown using one-way Mann-Whitney. Mean and standard deviation (st. dev.) are shown in black.