(Invited Talk) Quantitative and Ultra-Sensitive Saliva Test with Cellphone for COVID-19

More than six months after the initial COVID-19 outbreak, most countries are still struggling to control COVID-19 disease transmission, and many are now observing increased infection rates in response to attempts to reopen public venues to reduce economic and social disruption. Current RT-PCR-based COVID-19 assays have drawbacks that limit their capacity for screening efforts required to inform such decisions, since they require significant technical expertise and expensive equipment; use nasopharyngeal samples that must be collected by well-trained personnel wearing extensive protective equipment; and miss a significant number of COVID-19 cases. Other recently approved assays can require less expensive equipment and technical expertise, but exhibit reduced sensitivity and specificity. We recently reported the development of a rapid and sensitive COVID-19 assay in which CRISPR-mediated activation of a fluorescent probe amplifies RT-PCR signal for SARS-CoV-2 RNA to increase assay sensitivity using nasopharyngeal swab samples. We now report that this approach demonstrated similar analytical sensitivity when applied to analyze saliva samples spiked with SARS-CoV-2 RNA, and that results from clinical saliva samples analyzed by this approach exhibited complete concordance with RT-PCR results from paired nasopharyngeal swab samples. This assay approach was used to directly detect SARS-CoV-2 RNA in saliva, without a separate RNA isolation step, and was not dependent upon specific incubation temperatures. We next demonstrated that this assay could be performed using a procedure that did not require any laboratory equipment, using an inexpensive 3D-printed adaptor to allow accurate and sensitive detection of SARS-CoV-2 RNA in clinical saliva samples for COVID-19 diagnosis.