Saliva-STAT: Sample-to-answer saliva test for COVID-19

Abstract

Highly accessible and highly accurate diagnostics are necessary to combat rapidly-spreading infectious diseases, such as the recent COVID-19 pandemic. While lateral flow antigen tests have become pervasive, they are insufficiently sensitive to detect early or asymptomatic disease. Nucleic acid amplification tests provide the needed sensitivity, but accessibility of these tests continues to be a challenge due to the need for precise sample processing steps. Here we report a sample-to-answer test for saliva samples (saliva-STAT) that utilizes a battery-powered handheld instrument and a low-cost easily-manufacturable sample cassette to perform a nucleic acid amplification test for viral pathogens. To enable a completely automated assay, we leverage thermally responsive alkane partitions (TRAPs) and paramagnetic beads for virus purification and concentration, as well as reagent addition and mixing. Notably, the saliva STAT easily accommodates directly-dispensed saliva samples (in contrast to microfluidic devices), which is necessary for self-testing. Using the saliva-STAT platform, we demonstrate detection of down to 0.2 copies/μL of SARS-CoV-2 virus in saliva samples. We envision that the saliva-STAT could be used in walk-in clinics, mobile clinics, public testing locations, and in the home. With minor adjustments to the assay, the saliva-STAT platform can easily be adapted for other respiratory viruses, such as Influenza.

Keywords: COVID-19; LAMP; SARS-CoV-2; point-of-care; saliva; sample-to-answer.