Extraction-Free Testing for SARS-CoV-2 in Nasal Swab and Saliva Samples on a Single High-Throughput Platform

Author(s): Yue Qiu, Ling Lu, Amanda Halven, Rachel Terrio, Sydney Yuldelson, Natalie Dougal, Filippo Galbo, Andrew Lu, Dexiang Gao, Bob Blomquist, Jose P Zevallos, Shi-Long Lu, Xin Yao, Brian L Harry

The COVID-19 pandemic introduced an urgent need for rapid and high-throughput testing for SARS-CoV-2. RNA extraction is a major bottleneck for RT-qPCR. We describe a semi-automated, extraction-free RT-qPCR assay for detection of SARS-CoV-2 in nasal swab and saliva samples on a single platform. With a limit of detection of 4 copies/mL, this laboratory developed test performed equivalently to established methods requiring nucleic acid extraction. Five technologists staffing two shifts per day (80 person-hours) processed more than 400,000 samples over 10 months. Patients opted to provide nasal swab samples (83.6%) more frequently than saliva (16.4%), creating the added challenge of producing swab collection kits. Real-world testing data indicated a higher frequency of SARS-CoV-2 detection in saliva (10.1%) compared to nasal swab (7.7%). This cost-effective and quickly scalable approach is suitable for pandemic preparedness planning related to surveillance and diagnostic testing.

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