Background: Circulating SARS-CoV-2 RNA may represent a more reliable indicator of infection than nasal RNA, but RT-qPCR lacks diagnostic sensitivity for blood samples. Methods: A CRISPR-augmented RT-PCR assay that sensitively detects SARS-CoV-2 RNA was employed to analyze viral RNA kinetics in longitudinal plasma samples from nonhuman primates (NHP) after virus exposure; to evaluate the utility of blood SARS-CoV-2 RNA detection for COVID-19 diagnosis in adults cases confirmed by nasal/nasopharyngeal swab RT-PCR results; and to identify suspected COVID-19 cases in pediatric and at-risk adult populations with negative nasal swab RT-qPCR results. All blood samples were analyzed by RT-qPCR to allow direct comparisons. Results: CRISPR-augmented RT-PCR consistently detected SARS-CoV-2 RNA in the plasma of experimentally infected NHPs from 1 to 28 days post-infection, and these increases preceded and correlated with rectal swab viral RNA increases. In a patient cohort (n=159), this blood-based assay demonstrated 91.2% diagnostic sensitivity and 99.2% diagnostic specificity versus a comparator RT-qPCR nasal/nasopharyngeal test, while RT-qPCR exhibited 44.1% diagnostic sensitivity and 100% specificity for the same blood samples. This CRISPR-augmented RT-PCR assay also accurately identified COVID-19 patients with one or more negative nasal swab RT-qPCR result. Conclusion: Results of this study indicate that sensitive detection of SARS-CoV-2 RNA in blood by CRISPR-augmented RT-PCR permits accurate COVID-19 diagnosis, and can detect COVID-19 cases with transient or negative nasal swab RT-qPCR results, suggesting that this approach could improve COVID-19 diagnosis and the evaluation of SARS-CoV-2 infection clearance, and predict the severity of infection.
Zhen Huang, Bo Ning, He S. Yang, Brady M. Youngquist, Alex Niu, Christopher J. Lyon, Brandon J. Beddingfield, Alyssa C. Fears, Chandler H. Monk, Amelie E. Murrell, Samantha J. Bilton, Joshua P. Linhuber, Elizabeth B. Norton, Monika L. Dietrich, Jim K. Yee, Weihua Lai, John W. Scott, Xiao-Ming Yin, Jay Rappaport, James E. Robinson, Nakhle S. Saba, Chad J. Roy, Kevin J. Zwezdaryk, Zhen Zhao, Tony Y. Hu