Background: Controlling novel coronavirus pandemic infection (COVID-19) is a global challenge, and highly sensitive testing is essential for effective control. The saliva is a promising sample for high-sensitivity testing because it is easier to collect than nasopharyngeal swab samples and allows large-volume testing. Results: We developed a simple SARS-CoV-2 concentration method from saliva samples that can be completed in less than 60 min. We performed a spike test using 12 ml of saliva samples obtained from healthy volunteer people, and the developed method performance was evaluated by comparison using a combination of automatic nucleic acid extraction followed by RT-qPCR detection. In saliva spike tests using a 10-fold dilution series of SARS-CoV-2, the developed method was consistently 100-fold more sensitive than the conventional method. Conclusions: The developed method can improve the sensitivity of the SARS-CoV-2 test using saliva and speed up and save labor in screening tests by pooling many samples. Furthermore, the developed method has the potential to contribute to the highly sensitive detection of various human and animal viral pathogens from the saliva and various clinical samples.

The authors have declared no competing interest.

This study was funded by AMED Number JP20he0622031, JSPS KAKENHI Numbers JP21H03180, JP22K05950, JP22KK0097, JSPS Bilateral Program Number JPJSBP120199944, and the Joint Usage/Research Center for Global Collaborative Research, Center for Southeast Asian Studies, Kyoto University.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The Ethics Committee of Kyoto University Graduate School and the Faculty of Medicine approved this study (R2379)

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All data produced in the present study are available upon reasonable request to the authors.