"Clinical characteristics of 24 asymptomatic infections with COVID-19 screened among close contacts in Nanjing, China." - https://link.springer.com/content/pdf/

"Clinical characteristics of 24 asymptomatic infections with COVID-19 screened among close contacts in Nanjing, China." - https://link.springer.com/content/pdf/10.1007/s11427-020-1661-4.pdf https://link.springer.com/content/pdf/10.1007/s11427-020-166.... It seems asymptomatic patients can test negative multiple times on RT-PCR assays but be diagnosed other ways. I've read somewhere that at least in China, the specificity of the PCR tests is only 60-70%, leaving ~30% undetected. From the Discussion section of this paper: https://pubs.rsna.org/doi/10.1148/radiol.2020200642 https://pubs.rsna.org/doi/10.1148/radiol.2020200642: "According to current diagnostic criterion, viral nucleic acid test by RT-PCR assay plays a vital role in determining hospitalization and isolation for individual patients. However, its lack of sensitivity, insufficient stability, and relatively long processing time were detrimental to the control of the disease epidemic. In our study, the positive rate of RT-PCR assay for throat swab samples was 59% (95%CI, 56%-62%) which was consistent with previous report (30 - 60%) (6). In addition, a number of any external factors may affect RT-PCR testing results including sampling operations, specimens source (upper or lower respiratory tract), sampling timing (different period of the disease development) (6), and performance of detection kits. As such, the results of RT-PCR tests must be cautiously interpreted."